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Observational Case Studies

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An observational case study is a study of a real-world case without performing an intervention. Measurement may influence the measured phenomena, but as in all forms of research, the researcher tries to restrict this to a minimum.

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Wieringa, R.J. (2014). Observational Case Studies. In: Design Science Methodology for Information Systems and Software Engineering. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-662-43839-8_17

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Research Process

What is Observational Study Design and Types

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Table of Contents

Most people think of a traditional experimental design when they consider research and published research papers. There is, however, a type of research that is more observational in nature, and it is appropriately referred to as “observational studies.”

There are many valuable reasons to utilize an observational study design. But, just as in research experimental design, different methods can be used when you’re considering this type of study. In this article, we’ll look at the advantages and disadvantages of an observational study design, as well as the 3 types of observational studies.

What is Observational Study Design?

An observational study is when researchers are looking at the effect of some type of intervention, risk, a diagnostic test or treatment, without trying to manipulate who is, or who isn’t, exposed to it.

This differs from an experimental study, where the scientists are manipulating who is exposed to the treatment, intervention, etc., by having a control group, or those who are not exposed, and an experimental group, or those who are exposed to the intervention, treatment, etc. In the best studies, the groups are randomized, or chosen by chance.

Any evidence derived from systematic reviews is considered the best in the hierarchy of evidence, which considers which studies are deemed the most reliable. Next would be any evidence that comes from randomized controlled trials. Cohort studies and case studies follow, in that order.

Cohort studies and case studies are considered observational in design, whereas the randomized controlled trial would be an experimental study.

Let’s take a closer look at the different types of observational study design.

The 3 types of Observational Studies

The different types of observational studies are used for different reasons. Selecting the best type for your research is critical to a successful outcome. One of the main reasons observational studies are used is when a randomized experiment would be considered unethical. For example, a life-saving medication used in a public health emergency. They are also used when looking at aetiology, or the cause of a condition or disease, as well as the treatment of rare conditions.

Case Control Observational Study

Researchers in case control studies identify individuals with an existing health issue or condition, or “cases,” along with a similar group without the condition, or “controls.” These two groups are then compared to identify predictors and outcomes. This type of study is helpful to generate a hypothesis that can then be researched.

Cohort Observational Study

This type of observational study is often used to help understand cause and effect. A cohort observational study looks at causes, incidence and prognosis, for example. A cohort is a group of people who are linked in a particular way, for example, a birth cohort would include people who were born within a specific period of time. Scientists might compare what happens to the members of the cohort who have been exposed to some variable to what occurs with members of the cohort who haven’t been exposed.

Cross Sectional Observational Study

Unlike a cohort observational study, a cross sectional observational study does not explore cause and effect, but instead looks at prevalence. Here you would look at data from a particular group at one very specific period of time. Researchers would simply observe and record information about something present in the population, without manipulating any variables or interventions. These types of studies are commonly used in psychology, education and social science.

Advantages and Disadvantages of Observational Study Design

Observational study designs have the distinct advantage of allowing researchers to explore answers to questions where a randomized controlled trial, or RCT, would be unethical. Additionally, if the study is focused on a rare condition, studying existing cases as compared to non-affected individuals might be the most effective way to identify possible causes of the condition. Likewise, if very little is known about a condition or circumstance, a cohort study would be a good study design choice.

A primary advantage to the observational study design is that they can generally be completed quickly and inexpensively. A RCT can take years before the data is compiled and available. RCTs are more complex and involved, requiring many more logistics and details to iron out, whereas an observational study can be more easily designed and completed.

The main disadvantage of observational study designs is that they’re more open to dispute than an RCT. Of particular concern would be confounding biases. This is when a cohort might share other characteristics that affect the outcome versus the outcome stated in the study. An example would be that people who practice good sleeping habits have less heart disease. But, maybe those who practice effective sleeping habits also, in general, eat better and exercise more.

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6.6: Observational Research

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Rajiv S. Jhangiani, I-Chant A. Chiang, Carrie Cuttler, & Dana C. Leighton

Rajiv S. Jhangiani, I-Chant A. Chiang, Carrie Cuttler, & Dana C. Leighton
Kwantlen Polytechnic U., Washington State U., & Texas A&M U.—Texarkana

Learning Objectives

List the various types of observational research methods and distinguish between each.
Describe the strengths and weakness of each observational research method.

What Is Observational Research?

The term observational research is used to refer to several different types of non-experimental studies in which behavior is systematically observed and recorded. The goal of observational research is to describe a variable or set of variables. More generally, the goal is to obtain a snapshot of specific characteristics of an individual, group, or setting. As described previously, observational research is non-experimental because nothing is manipulated or controlled, and as such we cannot arrive at causal conclusions using this approach. The data that are collected in observational research studies are often qualitative in nature but they may also be quantitative or both (mixed-methods). There are several different types of observational methods that will be described below.

Naturalistic Observation

Naturalistic observation is an observational method that involves observing people’s behavior in the environment in which it typically occurs. Thus naturalistic observation is a type of field research (as opposed to a type of laboratory research). Jane Goodall’s famous research on chimpanzees is a classic example of naturalistic observation. Dr. Goodall spent three decades observing chimpanzees in their natural environment in East Africa. She examined such things as chimpanzee’s social structure, mating patterns, gender roles, family structure, and care of offspring by observing them in the wild. However, naturalistic observation could more simply involve observing shoppers in a grocery store, children on a school playground, or psychiatric inpatients in their wards. Researchers engaged in naturalistic observation usually make their observations as unobtrusively as possible so that participants are not aware that they are being studied. Such an approach is called disguised naturalistic observation. Ethically, this method is considered to be acceptable if the participants remain anonymous and the behavior occurs in a public setting where people would not normally have an expectation of privacy. Grocery shoppers putting items into their shopping carts, for example, are engaged in public behavior that is easily observable by store employees and other shoppers. For this reason, most researchers would consider it ethically acceptable to observe them for a study. On the other hand, one of the arguments against the ethicality of the naturalistic observation of “bathroom behavior” discussed earlier in the book is that people have a reasonable expectation of privacy even in a public restroom and that this expectation was violated.

In cases where it is not ethical or practical to conduct disguised naturalistic observation, researchers can conduct undisguised naturalistic observation where the participants are made aware of the researcher presence and monitoring of their behavior. However, one concern with undisguised naturalistic observation is reactivity. Reactivity refers to when a measure changes participants’ behavior. In the case of undisguised naturalistic observation, the concern with reactivity is that when people know they are being observed and studied, they may act differently than they normally would. This type of reactivity is known as the Hawthorne effect . For instance, you may act much differently in a bar if you know that someone is observing you and recording your behaviors and this would invalidate the study. So disguised observation is less reactive and therefore can have higher validity because people are not aware that their behaviors are being observed and recorded. However, we now know that people often become used to being observed and with time they begin to behave naturally in the researcher’s presence. In other words, over time people habituate to being observed. Think about reality shows like Big Brother or Survivor where people are constantly being observed and recorded. While they may be on their best behavior at first, in a fairly short amount of time they are flirting, having sex, wearing next to nothing, screaming at each other, and occasionally behaving in ways that are embarrassing.

Participant Observation

In a famous example of disguised participant observation, Leon Festinger and his colleagues infiltrated a doomsday cult known as the Seekers, whose members believed that the apocalypse would occur on December 21, 1954. Interested in studying how members of the group would cope psychologically when the prophecy inevitably failed, they carefully recorded the events and reactions of the cult members in the days before and after the supposed end of the world. Unsurprisingly, the cult members did not give up their belief but instead convinced themselves that it was their faith and efforts that saved the world from destruction. Festinger and his colleagues later published a book about this experience, which they used to illustrate the theory of cognitive dissonance (Festinger, Riecken, & Schachter, 1956) [1] .

In contrast with undisguised participant observation, the researchers become a part of the group they are studying and they disclose their true identity as researchers to the group under investigation. Once again there are important ethical issues to consider with disguised participant observation. First no informed consent can be obtained and second deception is being used. The researcher is deceiving the participants by intentionally withholding information about their motivations for being a part of the social group they are studying. But sometimes disguised participation is the only way to access a protective group (like a cult). Further, disguised participant observation is less prone to reactivity than undisguised participant observation.

Rosenhan’s study (1973) [2] of the experience of people in a psychiatric ward would be considered disguised participant observation because Rosenhan and his pseudopatients were admitted into psychiatric hospitals on the pretense of being patients so that they could observe the way that psychiatric patients are treated by staff. The staff and other patients were unaware of their true identities as researchers.

Another example of participant observation comes from a study by sociologist Amy Wilkins on a university-based religious organization that emphasized how happy its members were (Wilkins, 2008) [3] . Wilkins spent 12 months attending and participating in the group’s meetings and social events, and she interviewed several group members. In her study, Wilkins identified several ways in which the group “enforced” happiness—for example, by continually talking about happiness, discouraging the expression of negative emotions, and using happiness as a way to distinguish themselves from other groups.

One of the primary benefits of participant observation is that the researchers are in a much better position to understand the viewpoint and experiences of the people they are studying when they are a part of the social group. The primary limitation with this approach is that the mere presence of the observer could affect the behavior of the people being observed. While this is also a concern with naturalistic observation, additional concerns arise when researchers become active members of the social group they are studying because that they may change the social dynamics and/or influence the behavior of the people they are studying. Similarly, if the researcher acts as a participant observer there can be concerns with biases resulting from developing relationships with the participants. Concretely, the researcher may become less objective resulting in more experimenter bias.

Structured Observation

Structured observation is very similar to naturalistic observation and participant observation in that in all three cases researchers are observing naturally occurring behavior; however, the emphasis in structured observation is on gathering quantitative rather than qualitative data. Researchers using this approach are interested in a limited set of behaviors. This allows them to quantify the behaviors they are observing. In other words, structured observation is less global than naturalistic or participant observation because the researcher engaged in structured observations is interested in a small number of specific behaviors. Therefore, rather than recording everything that happens, the researcher only focuses on very specific behaviors of interest.

Researchers Robert Levine and Ara Norenzayan used structured observation to study differences in the “pace of life” across countries (Levine & Norenzayan, 1999) [4] . One of their measures involved observing pedestrians in a large city to see how long it took them to walk 60 feet. They found that people in some countries walked reliably faster than people in other countries. For example, people in Canada and Sweden covered 60 feet in just under 13 seconds on average, while people in Brazil and Romania took close to 17 seconds. When structured observation takes place in the complex and even chaotic “real world,” the questions of when, where, and under what conditions the observations will be made, and who exactly will be observed are important to consider. Levine and Norenzayan described their sampling process as follows:

Precise specification of the sampling process in this way makes data collection manageable for the observers, and it also provides some control over important extraneous variables. For example, by making their observations on clear summer days in all countries, Levine and Norenzayan controlled for effects of the weather on people’s walking speeds. In Levine and Norenzayan’s study, measurement was relatively straightforward. They simply measured out a 60-foot distance along a city sidewalk and then used a stopwatch to time participants as they walked over that distance.

As another example, researchers Robert Kraut and Robert Johnston wanted to study bowlers’ reactions to their shots, both when they were facing the pins and then when they turned toward their companions (Kraut & Johnston, 1979) [5] . But what “reactions” should they observe? Based on previous research and their own pilot testing, Kraut and Johnston created a list of reactions that included “closed smile,” “open smile,” “laugh,” “neutral face,” “look down,” “look away,” and “face cover” (covering one’s face with one’s hands). The observers committed this list to memory and then practiced by coding the reactions of bowlers who had been videotaped. During the actual study, the observers spoke into an audio recorder, describing the reactions they observed. Among the most interesting results of this study was that bowlers rarely smiled while they still faced the pins. They were much more likely to smile after they turned toward their companions, suggesting that smiling is not purely an expression of happiness but also a form of social communication.

In yet another example (this one in a laboratory environment), Dov Cohen and his colleagues had observers rate the emotional reactions of participants who had just been deliberately bumped and insulted by a confederate after they dropped off a completed questionnaire at the end of a hallway. The confederate was posing as someone who worked in the same building and who was frustrated by having to close a file drawer twice in order to permit the participants to walk past them (first to drop off the questionnaire at the end of the hallway and once again on their way back to the room where they believed the study they signed up for was taking place). The two observers were positioned at different ends of the hallway so that they could read the participants’ body language and hear anything they might say. Interestingly, the researchers hypothesized that participants from the southern United States, which is one of several places in the world that has a “culture of honor,” would react with more aggression than participants from the northern United States, a prediction that was in fact supported by the observational data (Cohen, Nisbett, Bowdle, & Schwarz, 1996) [6] .

When the observations require a judgment on the part of the observers—as in the studies by Kraut and Johnston and Cohen and his colleagues—a process referred to as coding is typically required . Coding generally requires clearly defining a set of target behaviors. The observers then categorize participants individually in terms of which behavior they have engaged in and the number of times they engaged in each behavior. The observers might even record the duration of each behavior. The target behaviors must be defined in such a way that guides different observers to code them in the same way. This difficulty with coding illustrates the issue of interrater reliability, as mentioned in Chapter 4. Researchers are expected to demonstrate the interrater reliability of their coding procedure by having multiple raters code the same behaviors independently and then showing that the different observers are in close agreement. Kraut and Johnston, for example, video recorded a subset of their participants’ reactions and had two observers independently code them. The two observers showed that they agreed on the reactions that were exhibited 97% of the time, indicating good interrater reliability.

One of the primary benefits of structured observation is that it is far more efficient than naturalistic and participant observation. Since the researchers are focused on specific behaviors this reduces time and expense. Also, often times the environment is structured to encourage the behaviors of interest which again means that researchers do not have to invest as much time in waiting for the behaviors of interest to naturally occur. Finally, researchers using this approach can clearly exert greater control over the environment. However, when researchers exert more control over the environment it may make the environment less natural which decreases external validity. It is less clear for instance whether structured observations made in a laboratory environment will generalize to a real world environment. Furthermore, since researchers engaged in structured observation are often not disguised there may be more concerns with reactivity.

Case Studies

A case study is an in-depth examination of an individual. Sometimes case studies are also completed on social units (e.g., a cult) and events (e.g., a natural disaster). Most commonly in psychology, however, case studies provide a detailed description and analysis of an individual. Often the individual has a rare or unusual condition or disorder or has damage to a specific region of the brain.

Like many observational research methods, case studies tend to be more qualitative in nature. Case study methods involve an in-depth, and often a longitudinal examination of an individual. Depending on the focus of the case study, individuals may or may not be observed in their natural setting. If the natural setting is not what is of interest, then the individual may be brought into a therapist’s office or a researcher’s lab for study. Also, the bulk of the case study report will focus on in-depth descriptions of the person rather than on statistical analyses. With that said some quantitative data may also be included in the write-up of a case study. For instance, an individual’s depression score may be compared to normative scores or their score before and after treatment may be compared. As with other qualitative methods, a variety of different methods and tools can be used to collect information on the case. For instance, interviews, naturalistic observation, structured observation, psychological testing (e.g., IQ test), and/or physiological measurements (e.g., brain scans) may be used to collect information on the individual.

HM is one of the most notorious case studies in psychology. HM suffered from intractable and very severe epilepsy. A surgeon localized HM’s epilepsy to his medial temporal lobe and in 1953 he removed large sections of his hippocampus in an attempt to stop the seizures. The treatment was a success, in that it resolved his epilepsy and his IQ and personality were unaffected. However, the doctors soon realized that HM exhibited a strange form of amnesia, called anterograde amnesia. HM was able to carry out a conversation and he could remember short strings of letters, digits, and words. Basically, his short term memory was preserved. However, HM could not commit new events to memory. He lost the ability to transfer information from his short-term memory to his long term memory, something memory researchers call consolidation. So while he could carry on a conversation with someone, he would completely forget the conversation after it ended. This was an extremely important case study for memory researchers because it suggested that there’s a dissociation between short-term memory and long-term memory, it suggested that these were two different abilities sub-served by different areas of the brain. It also suggested that the temporal lobes are particularly important for consolidating new information (i.e., for transferring information from short-term memory to long-term memory),

The history of psychology is filled with influential cases studies, such as Sigmund Freud’s description of “Anna O.” (see Note 6.1 “The Case of “Anna O.””) and John Watson and Rosalie Rayner’s description of Little Albert (Watson & Rayner, 1920) [7] , who allegedly learned to fear a white rat—along with other furry objects—when the researchers repeatedly made a loud noise every time the rat approached him.

The Case of “Anna O.”

Sigmund Freud used the case of a young woman he called “Anna O.” to illustrate many principles of his theory of psychoanalysis (Freud, 1961) [8] . (Her real name was Bertha Pappenheim, and she was an early feminist who went on to make important contributions to the field of social work.) Anna had come to Freud’s colleague Josef Breuer around 1880 with a variety of odd physical and psychological symptoms. One of them was that for several weeks she was unable to drink any fluids. According to Freud,

She would take up the glass of water that she longed for, but as soon as it touched her lips she would push it away like someone suffering from hydrophobia.…She lived only on fruit, such as melons, etc., so as to lessen her tormenting thirst. (p. 9)

But according to Freud, a breakthrough came one day while Anna was under hypnosis.

[S]he grumbled about her English “lady-companion,” whom she did not care for, and went on to describe, with every sign of disgust, how she had once gone into this lady’s room and how her little dog—horrid creature!—had drunk out of a glass there. The patient had said nothing, as she had wanted to be polite. After giving further energetic expression to the anger she had held back, she asked for something to drink, drank a large quantity of water without any difficulty, and awoke from her hypnosis with the glass at her lips; and thereupon the disturbance vanished, never to return. (p.9)

Freud’s interpretation was that Anna had repressed the memory of this incident along with the emotion that it triggered and that this was what had caused her inability to drink. Furthermore, he believed that her recollection of the incident, along with her expression of the emotion she had repressed, caused the symptom to go away.

As an illustration of Freud’s theory, the case study of Anna O. is quite effective. As evidence for the theory, however, it is essentially worthless. The description provides no way of knowing whether Anna had really repressed the memory of the dog drinking from the glass, whether this repression had caused her inability to drink, or whether recalling this “trauma” relieved the symptom. It is also unclear from this case study how typical or atypical Anna’s experience was.

However, it is important to note that while case studies can provide insights into certain areas and variables to study, and can be useful in helping develop theories, they should never be used as evidence for theories. In other words, case studies can be used as inspiration to formulate theories and hypotheses, but those hypotheses and theories then need to be formally tested using more rigorous quantitative methods. The reason case studies shouldn’t be used to provide support for theories is that they suffer from problems with both internal and external validity. Case studies lack the proper controls that true experiments contain. As such, they suffer from problems with internal validity, so they cannot be used to determine causation. For instance, during HM’s surgery, the surgeon may have accidentally lesioned another area of HM’s brain (a possibility suggested by the dissection of HM’s brain following his death) and that lesion may have contributed to his inability to consolidate new information. The fact is, with case studies we cannot rule out these sorts of alternative explanations. So, as with all observational methods, case studies do not permit determination of causation. In addition, because case studies are often of a single individual, and typically an abnormal individual, researchers cannot generalize their conclusions to other individuals. Recall that with most research designs there is a trade-off between internal and external validity. With case studies, however, there are problems with both internal validity and external validity. So there are limits both to the ability to determine causation and to generalize the results. A final limitation of case studies is that ample opportunity exists for the theoretical biases of the researcher to color or bias the case description. Indeed, there have been accusations that the woman who studied HM destroyed a lot of her data that were not published and she has been called into question for destroying contradictory data that didn’t support her theory about how memories are consolidated. There is a fascinating New York Times article that describes some of the controversies that ensued after HM’s death and analysis of his brain that can be found at: https://www.nytimes.com/2016/08/07/magazine/the-brain-that-couldnt-remember.html?_r=0

Archival Research

Another approach that is often considered observational research involves analyzing archival data that have already been collected for some other purpose. An example is a study by Brett Pelham and his colleagues on “implicit egotism”—the tendency for people to prefer people, places, and things that are similar to themselves (Pelham, Carvallo, & Jones, 2005) [9] . In one study, they examined Social Security records to show that women with the names Virginia, Georgia, Louise, and Florence were especially likely to have moved to the states of Virginia, Georgia, Louisiana, and Florida, respectively.

As with naturalistic observation, measurement can be more or less straightforward when working with archival data. For example, counting the number of people named Virginia who live in various states based on Social Security records is relatively straightforward. But consider a study by Christopher Peterson and his colleagues on the relationship between optimism and health using data that had been collected many years before for a study on adult development (Peterson, Seligman, & Vaillant, 1988) [10] . In the 1940s, healthy male college students had completed an open-ended questionnaire about difficult wartime experiences. In the late 1980s, Peterson and his colleagues reviewed the men’s questionnaire responses to obtain a measure of explanatory style—their habitual ways of explaining bad events that happen to them. More pessimistic people tend to blame themselves and expect long-term negative consequences that affect many aspects of their lives, while more optimistic people tend to blame outside forces and expect limited negative consequences. To obtain a measure of explanatory style for each participant, the researchers used a procedure in which all negative events mentioned in the questionnaire responses, and any causal explanations for them were identified and written on index cards. These were given to a separate group of raters who rated each explanation in terms of three separate dimensions of optimism-pessimism. These ratings were then averaged to produce an explanatory style score for each participant. The researchers then assessed the statistical relationship between the men’s explanatory style as undergraduate students and archival measures of their health at approximately 60 years of age. The primary result was that the more optimistic the men were as undergraduate students, the healthier they were as older men. Pearson’s r was +.25.

This method is an example of content analysis —a family of systematic approaches to measurement using complex archival data. Just as structured observation requires specifying the behaviors of interest and then noting them as they occur, content analysis requires specifying keywords, phrases, or ideas and then finding all occurrences of them in the data. These occurrences can then be counted, timed (e.g., the amount of time devoted to entertainment topics on the nightly news show), or analyzed in a variety of other ways.

Festinger, L., Riecken, H., & Schachter, S. (1956). When prophecy fails: A social and psychological study of a modern group that predicted the destruction of the world. University of Minnesota Press. ↵
Rosenhan, D. L. (1973). On being sane in insane places. Science, 179 , 250–258. ↵
Wilkins, A. (2008). “Happier than Non-Christians”: Collective emotions and symbolic boundaries among evangelical Christians. Social Psychology Quarterly, 71 , 281–301. ↵
Levine, R. V., & Norenzayan, A. (1999). The pace of life in 31 countries. Journal of Cross-Cultural Psychology, 30 , 178–205. ↵
Kraut, R. E., & Johnston, R. E. (1979). Social and emotional messages of smiling: An ethological approach. Journal of Personality and Social Psychology, 37 , 1539–1553. ↵
Cohen, D., Nisbett, R. E., Bowdle, B. F., & Schwarz, N. (1996). Insult, aggression, and the southern culture of honor: An "experimental ethnography." Journal of Personality and Social Psychology, 70 (5), 945-960. ↵
Watson, J. B., & Rayner, R. (1920). Conditioned emotional reactions. Journal of Experimental Psychology, 3 , 1–14. ↵
Freud, S. (1961). Five lectures on psycho-analysis . New York, NY: Norton. ↵
Pelham, B. W., Carvallo, M., & Jones, J. T. (2005). Implicit egotism. Current Directions in Psychological Science, 14 , 106–110. ↵
Peterson, C., Seligman, M. E. P., & Vaillant, G. E. (1988). Pessimistic explanatory style is a risk factor for physical illness: A thirty-five year longitudinal study. Journal of Personality and Social Psychology, 55 , 23–27. ↵

6.5 Observational Research

Learning objectives.

List the various types of observational research methods and distinguish between each
Describe the strengths and weakness of each observational research method.

What Is Observational Research?

Naturalistic Observation

In cases where it is not ethical or practical to conduct disguised naturalistic observation, researchers can conduct undisguised naturalistic observation where the participants are made aware of the researcher presence and monitoring of their behavior. However, one concern with undisguised naturalistic observation is reactivity. Reactivity refers to when a measure changes participants’ behavior. In the case of undisguised naturalistic observation, the concern with reactivity is that when people know they are being observed and studied, they may act differently than they normally would. For instance, you may act much differently in a bar if you know that someone is observing you and recording your behaviors and this would invalidate the study. So disguised observation is less reactive and therefore can have higher validity because people are not aware that their behaviors are being observed and recorded. However, we now know that people often become used to being observed and with time they begin to behave naturally in the researcher’s presence. In other words, over time people habituate to being observed. Think about reality shows like Big Brother or Survivor where people are constantly being observed and recorded. While they may be on their best behavior at first, in a fairly short amount of time they are, flirting, having sex, wearing next to nothing, screaming at each other, and at times acting like complete fools in front of the entire nation.

Participant Observation

Another approach to data collection in observational research is participant observation. In participant observation , researchers become active participants in the group or situation they are studying. Participant observation is very similar to naturalistic observation in that it involves observing people’s behavior in the environment in which it typically occurs. As with naturalistic observation, the data that is collected can include interviews (usually unstructured), notes based on their observations and interactions, documents, photographs, and other artifacts. The only difference between naturalistic observation and participant observation is that researchers engaged in participant observation become active members of the group or situations they are studying. The basic rationale for participant observation is that there may be important information that is only accessible to, or can be interpreted only by, someone who is an active participant in the group or situation. Like naturalistic observation, participant observation can be either disguised or undisguised. In disguised participant observation, the researchers pretend to be members of the social group they are observing and conceal their true identity as researchers. In contrast with undisguised participant observation, the researchers become a part of the group they are studying and they disclose their true identity as researchers to the group under investigation. Once again there are important ethical issues to consider with disguised participant observation. First no informed consent can be obtained and second passive deception is being used. The researcher is passively deceiving the participants by intentionally withholding information about their motivations for being a part of the social group they are studying. But sometimes disguised participation is the only way to access a protective group (like a cult). Further, disguised participant observation is less prone to reactivity than undisguised participant observation.

Rosenhan’s study (1973) [1] of the experience of people in a psychiatric ward would be considered disguised participant observation because Rosenhan and his pseudopatients were admitted into psychiatric hospitals on the pretense of being patients so that they could observe the way that psychiatric patients are treated by staff. The staff and other patients were unaware of their true identities as researchers.

Another example of participant observation comes from a study by sociologist Amy Wilkins (published in Social Psychology Quarterly ) on a university-based religious organization that emphasized how happy its members were (Wilkins, 2008) [2] . Wilkins spent 12 months attending and participating in the group’s meetings and social events, and she interviewed several group members. In her study, Wilkins identified several ways in which the group “enforced” happiness—for example, by continually talking about happiness, discouraging the expression of negative emotions, and using happiness as a way to distinguish themselves from other groups.

One of the primary benefits of participant observation is that the researcher is in a much better position to understand the viewpoint and experiences of the people they are studying when they are apart of the social group. The primary limitation with this approach is that the mere presence of the observer could affect the behavior of the people being observed. While this is also a concern with naturalistic observation when researchers because active members of the social group they are studying, additional concerns arise that they may change the social dynamics and/or influence the behavior of the people they are studying. Similarly, if the researcher acts as a participant observer there can be concerns with biases resulting from developing relationships with the participants. Concretely, the researcher may become less objective resulting in more experimenter bias.

Structured Observation

Another observational method is structured observation. Here the investigator makes careful observations of one or more specific behaviors in a particular setting that is more structured than the settings used in naturalistic and participant observation. Often the setting in which the observations are made is not the natural setting, rather the researcher may observe people in the laboratory environment. Alternatively, the researcher may observe people in a natural setting (like a classroom setting) that they have structured some way, for instance by introducing some specific task participants are to engage in or by introducing a specific social situation or manipulation. Structured observation is very similar to naturalistic observation and participant observation in that in all cases researchers are observing naturally occurring behavior, however, the emphasis in structured observation is on gathering quantitative rather than qualitative data. Researchers using this approach are interested in a limited set of behaviors. This allows them to quantify the behaviors they are observing. In other words, structured observation is less global than naturalistic and participant observation because the researcher engaged in structured observations is interested in a small number of specific behaviors. Therefore, rather than recording everything that happens, the researcher only focuses on very specific behaviors of interest.

Structured observation is very similar to naturalistic observation and participant observation in that in all cases researchers are observing naturally occurring behavior, however, the emphasis in structured observation is on gathering quantitative rather than qualitative data. Researchers using this approach are interested in a limited set of behaviors. This allows them to quantify the behaviors they are observing. In other words, structured observation is less global than naturalistic and participant observation because the researcher engaged in structured observations is interested in a small number of specific behaviors. Therefore, rather than recording everything that happens, the researcher only focuses on very specific behaviors of interest.

Researchers Robert Levine and Ara Norenzayan used structured observation to study differences in the “pace of life” across countries (Levine & Norenzayan, 1999) [3] . One of their measures involved observing pedestrians in a large city to see how long it took them to walk 60 feet. They found that people in some countries walked reliably faster than people in other countries. For example, people in Canada and Sweden covered 60 feet in just under 13 seconds on average, while people in Brazil and Romania took close to 17 seconds. When structured observation takes place in the complex and even chaotic “real world,” the questions of when, where, and under what conditions the observations will be made, and who exactly will be observed are important to consider. Levine and Norenzayan described their sampling process as follows:

“Male and female walking speed over a distance of 60 feet was measured in at least two locations in main downtown areas in each city. Measurements were taken during main business hours on clear summer days. All locations were flat, unobstructed, had broad sidewalks, and were sufficiently uncrowded to allow pedestrians to move at potentially maximum speeds. To control for the effects of socializing, only pedestrians walking alone were used. Children, individuals with obvious physical handicaps, and window-shoppers were not timed. Thirty-five men and 35 women were timed in most cities.” (p. 186). Precise specification of the sampling process in this way makes data collection manageable for the observers, and it also provides some control over important extraneous variables. For example, by making their observations on clear summer days in all countries, Levine and Norenzayan controlled for effects of the weather on people’s walking speeds. In Levine and Norenzayan’s study, measurement was relatively straightforward. They simply measured out a 60-foot distance along a city sidewalk and then used a stopwatch to time participants as they walked over that distance.

As another example, researchers Robert Kraut and Robert Johnston wanted to study bowlers’ reactions to their shots, both when they were facing the pins and then when they turned toward their companions (Kraut & Johnston, 1979) [4] . But what “reactions” should they observe? Based on previous research and their own pilot testing, Kraut and Johnston created a list of reactions that included “closed smile,” “open smile,” “laugh,” “neutral face,” “look down,” “look away,” and “face cover” (covering one’s face with one’s hands). The observers committed this list to memory and then practiced by coding the reactions of bowlers who had been videotaped. During the actual study, the observers spoke into an audio recorder, describing the reactions they observed. Among the most interesting results of this study was that bowlers rarely smiled while they still faced the pins. They were much more likely to smile after they turned toward their companions, suggesting that smiling is not purely an expression of happiness but also a form of social communication.

When the observations require a judgment on the part of the observers—as in Kraut and Johnston’s study—this process is often described as coding . Coding generally requires clearly defining a set of target behaviors. The observers then categorize participants individually in terms of which behavior they have engaged in and the number of times they engaged in each behavior. The observers might even record the duration of each behavior. The target behaviors must be defined in such a way that different observers code them in the same way. This difficulty with coding is the issue of interrater reliability, as mentioned in Chapter 4. Researchers are expected to demonstrate the interrater reliability of their coding procedure by having multiple raters code the same behaviors independently and then showing that the different observers are in close agreement. Kraut and Johnston, for example, video recorded a subset of their participants’ reactions and had two observers independently code them. The two observers showed that they agreed on the reactions that were exhibited 97% of the time, indicating good interrater reliability.

One of the primary benefits of structured observation is that it is far more efficient than naturalistic and participant observation. Since the researchers are focused on specific behaviors this reduces time and expense. Also, often times the environment is structured to encourage the behaviors of interested which again means that researchers do not have to invest as much time in waiting for the behaviors of interest to naturally occur. Finally, researchers using this approach can clearly exert greater control over the environment. However, when researchers exert more control over the environment it may make the environment less natural which decreases external validity. It is less clear for instance whether structured observations made in a laboratory environment will generalize to a real world environment. Furthermore, since researchers engaged in structured observation are often not disguised there may be more concerns with reactivity.

Case Studies

Like many observational research methods, case studies tend to be more qualitative in nature. Case study methods involve an in-depth, and often a longitudinal examination of an individual. Depending on the focus of the case study, individuals may or may not be observed in their natural setting. If the natural setting is not what is of interest, then the individual may be brought into a therapist’s office or a researcher’s lab for study. Also, the bulk of the case study report will focus on in-depth descriptions of the person rather than on statistical analyses. With that said some quantitative data may also be included in the write-up of a case study. For instance, an individuals’ depression score may be compared to normative scores or their score before and after treatment may be compared. As with other qualitative methods, a variety of different methods and tools can be used to collect information on the case. For instance, interviews, naturalistic observation, structured observation, psychological testing (e.g., IQ test), and/or physiological measurements (e.g., brain scans) may be used to collect information on the individual.

www.youtube.com/watch?v=KkaXNvzE4pk

The history of psychology is filled with influential cases studies, such as Sigmund Freud’s description of “Anna O.” (see Note 6.1 “The Case of “Anna O.””) and John Watson and Rosalie Rayner’s description of Little Albert (Watson & Rayner, 1920) [5] , who learned to fear a white rat—along with other furry objects—when the researchers made a loud noise while he was playing with the rat.

The Case of “Anna O.”

Sigmund Freud used the case of a young woman he called “Anna O.” to illustrate many principles of his theory of psychoanalysis (Freud, 1961) [6] . (Her real name was Bertha Pappenheim, and she was an early feminist who went on to make important contributions to the field of social work.) Anna had come to Freud’s colleague Josef Breuer around 1880 with a variety of odd physical and psychological symptoms. One of them was that for several weeks she was unable to drink any fluids. According to Freud,

But according to Freud, a breakthrough came one day while Anna was under hypnosis.

Freud’s interpretation was that Anna had repressed the memory of this incident along with the emotion that it triggered and that this was what had caused her inability to drink. Furthermore, her recollection of the incident, along with her expression of the emotion she had repressed, caused the symptom to go away.

Figure 10.1 Anna O. “Anna O.” was the subject of a famous case study used by Freud to illustrate the principles of psychoanalysis. Source: http://en.wikipedia.org/wiki/File:Pappenheim_1882.jpg

Case studies are useful because they provide a level of detailed analysis not found in many other research methods and greater insights may be gained from this more detailed analysis. As a result of the case study, the researcher may gain a sharpened understanding of what might become important to look at more extensively in future more controlled research. Case studies are also often the only way to study rare conditions because it may be impossible to find a large enough sample to individuals with the condition to use quantitative methods. Although at first glance a case study of a rare individual might seem to tell us little about ourselves, they often do provide insights into normal behavior. The case of HM provided important insights into the role of the hippocampus in memory consolidation. However, it is important to note that while case studies can provide insights into certain areas and variables to study, and can be useful in helping develop theories, they should never be used as evidence for theories. In other words, case studies can be used as inspiration to formulate theories and hypotheses, but those hypotheses and theories then need to be formally tested using more rigorous quantitative methods.

The reason case studies shouldn’t be used to provide support for theories is that they suffer from problems with internal and external validity. Case studies lack the proper controls that true experiments contain. As such they suffer from problems with internal validity, so they cannot be used to determine causation. For instance, during HM’s surgery, the surgeon may have accidentally lesioned another area of HM’s brain (indeed questioning into the possibility of a separate brain lesion began after HM’s death and dissection of his brain) and that lesion may have contributed to his inability to consolidate new information. The fact is, with case studies we cannot rule out these sorts of alternative explanations. So as with all observational methods case studies do not permit determination of causation. In addition, because case studies are often of a single individual, and typically a very abnormal individual, researchers cannot generalize their conclusions to other individuals. Recall that with most research designs there is a trade-off between internal and external validity, with case studies, however, there are problems with both internal validity and external validity. So there are limits both to the ability to determine causation and to generalize the results. A final limitation of case studies is that ample opportunity exists for the theoretical biases of the researcher to color or bias the case description. Indeed, there have been accusations that the woman who studied HM destroyed a lot of her data that were not published and she has been called into question for destroying contradictory data that didn’t support her theory about how memories are consolidated. There is a fascinating New York Times article that describes some of the controversies that ensued after HM’s death and analysis of his brain that can be found at: https://www.nytimes.com/2016/08/07/magazine/the-brain-that-couldnt-remember.html?_r=0

Archival Research

Another approach that is often considered observational research is the use of archival research which involves analyzing data that have already been collected for some other purpose. An example is a study by Brett Pelham and his colleagues on “implicit egotism”—the tendency for people to prefer people, places, and things that are similar to themselves (Pelham, Carvallo, & Jones, 2005) [7] . In one study, they examined Social Security records to show that women with the names Virginia, Georgia, Louise, and Florence were especially likely to have moved to the states of Virginia, Georgia, Louisiana, and Florida, respectively.

As with naturalistic observation, measurement can be more or less straightforward when working with archival data. For example, counting the number of people named Virginia who live in various states based on Social Security records is relatively straightforward. But consider a study by Christopher Peterson and his colleagues on the relationship between optimism and health using data that had been collected many years before for a study on adult development (Peterson, Seligman, & Vaillant, 1988) [8] . In the 1940s, healthy male college students had completed an open-ended questionnaire about difficult wartime experiences. In the late 1980s, Peterson and his colleagues reviewed the men’s questionnaire responses to obtain a measure of explanatory style—their habitual ways of explaining bad events that happen to them. More pessimistic people tend to blame themselves and expect long-term negative consequences that affect many aspects of their lives, while more optimistic people tend to blame outside forces and expect limited negative consequences. To obtain a measure of explanatory style for each participant, the researchers used a procedure in which all negative events mentioned in the questionnaire responses, and any causal explanations for them were identified and written on index cards. These were given to a separate group of raters who rated each explanation in terms of three separate dimensions of optimism-pessimism. These ratings were then averaged to produce an explanatory style score for each participant. The researchers then assessed the statistical relationship between the men’s explanatory style as undergraduate students and archival measures of their health at approximately 60 years of age. The primary result was that the more optimistic the men were as undergraduate students, the healthier they were as older men. Pearson’s r was +.25.

Key Takeaways

There are several different approaches to observational research including naturalistic observation, participant observation, structured observation, case studies, and archival research.
Naturalistic observation is used to observe people in their natural setting, participant observation involves becoming an active member of the group being observed, structured observation involves coding a small number of behaviors in a quantitative manner, case studies are typically used to collect in-depth information on a single individual, and archival research involves analysing existing data.
Describe one problem related to internal validity.
Describe one problem related to external validity.
Generate one hypothesis suggested by the case study that might be interesting to test in a systematic single-subject or group study.
Rosenhan, D. L. (1973). On being sane in insane places. Science, 179 , 250–258. ↵
Wilkins, A. (2008). “Happier than Non-Christians”: Collective emotions and symbolic boundaries among evangelical Christians. Social Psychology Quarterly, 71 , 281–301. ↵
Levine, R. V., & Norenzayan, A. (1999). The pace of life in 31 countries. Journal of Cross-Cultural Psychology, 30 , 178–205. ↵
Kraut, R. E., & Johnston, R. E. (1979). Social and emotional messages of smiling: An ethological approach. Journal of Personality and Social Psychology, 37 , 1539–1553. ↵
Watson, J. B., & Rayner, R. (1920). Conditioned emotional reactions. Journal of Experimental Psychology, 3 , 1–14. ↵
Freud, S. (1961). Five lectures on psycho-analysis . New York, NY: Norton. ↵
Pelham, B. W., Carvallo, M., & Jones, J. T. (2005). Implicit egotism. Current Directions in Psychological Science, 14 , 106–110. ↵
Peterson, C., Seligman, M. E. P., & Vaillant, G. E. (1988). Pessimistic explanatory style is a risk factor for physical illness: A thirty-five year longitudinal study. Journal of Personality and Social Psychology, 55 , 23–27. ↵

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Observational studies: cohort and case-control studies

Affiliation.

1 Ann Arbor, Mich. From the Section of Plastic Surgery, Department of Surgery, University of Michigan Health System.
PMID: 20697313
PMCID: PMC2998589
DOI: 10.1097/PRS.0b013e3181f44abc

Observational studies constitute an important category of study designs. To address some investigative questions in plastic surgery, randomized controlled trials are not always indicated or ethical to conduct. Instead, observational studies may be the next best method of addressing these types of questions. Well-designed observational studies have been shown to provide results similar to those of randomized controlled trials, challenging the belief that observational studies are second rate. Cohort studies and case-control studies are two primary types of observational studies that aid in evaluating associations between diseases and exposures. In this review article, the authors describe these study designs and methodologic issues, and provide examples from the plastic surgery literature.

Publication types

Research Support, N.I.H., Extramural
Case-Control Studies*
Cohort Studies*
Evidence-Based Medicine*
Plastic Surgery Procedures / methods*
Plastic Surgery Procedures / standards*
Prospective Studies
Randomized Controlled Trials as Topic
Retrospective Studies

Grants and funding

F32 AR058105/AR/NIAMS NIH HHS/United States
K24 AR053120/AR/NIAMS NIH HHS/United States
K24 AR053120-01A2/AR/NIAMS NIH HHS/United States

Observation Method in Psychology: Naturalistic, Participant and Controlled

Saul Mcleod, PhD

Editor-in-Chief for Simply Psychology

BSc (Hons) Psychology, MRes, PhD, University of Manchester

Saul Mcleod, PhD., is a qualified psychology teacher with over 18 years of experience in further and higher education. He has been published in peer-reviewed journals, including the Journal of Clinical Psychology.

Learn about our Editorial Process

Olivia Guy-Evans, MSc

Associate Editor for Simply Psychology

BSc (Hons) Psychology, MSc Psychology of Education

Olivia Guy-Evans is a writer and associate editor for Simply Psychology. She has previously worked in healthcare and educational sectors.

On This Page:

The observation method in psychology involves directly and systematically witnessing and recording measurable behaviors, actions, and responses in natural or contrived settings without attempting to intervene or manipulate what is being observed.

Used to describe phenomena, generate hypotheses, or validate self-reports, psychological observation can be either controlled or naturalistic with varying degrees of structure imposed by the researcher.

There are different types of observational methods, and distinctions need to be made between:

1. Controlled Observations 2. Naturalistic Observations 3. Participant Observations

In addition to the above categories, observations can also be either overt/disclosed (the participants know they are being studied) or covert/undisclosed (the researcher keeps their real identity a secret from the research subjects, acting as a genuine member of the group).

In general, conducting observational research is relatively inexpensive, but it remains highly time-consuming and resource-intensive in data processing and analysis.

The considerable investments needed in terms of coder time commitments for training, maintaining reliability, preventing drift, and coding complex dynamic interactions place practical barriers on observers with limited resources.

Controlled Observation

Controlled observation is a research method for studying behavior in a carefully controlled and structured environment.

The researcher sets specific conditions, variables, and procedures to systematically observe and measure behavior, allowing for greater control and comparison of different conditions or groups.

The researcher decides where the observation will occur, at what time, with which participants, and in what circumstances, and uses a standardized procedure. Participants are randomly allocated to each independent variable group.

Rather than writing a detailed description of all behavior observed, it is often easier to code behavior according to a previously agreed scale using a behavior schedule (i.e., conducting a structured observation).

The researcher systematically classifies the behavior they observe into distinct categories. Coding might involve numbers or letters to describe a characteristic or the use of a scale to measure behavior intensity.

The categories on the schedule are coded so that the data collected can be easily counted and turned into statistics.

For example, Mary Ainsworth used a behavior schedule to study how infants responded to brief periods of separation from their mothers. During the Strange Situation procedure, the infant’s interaction behaviors directed toward the mother were measured, e.g.,

Proximity and contact-seeking
Contact maintaining
Avoidance of proximity and contact
Resistance to contact and comforting

The observer noted down the behavior displayed during 15-second intervals and scored the behavior for intensity on a scale of 1 to 7.

Sometimes participants’ behavior is observed through a two-way mirror, or they are secretly filmed. Albert Bandura used this method to study aggression in children (the Bobo doll studies ).

A lot of research has been carried out in sleep laboratories as well. Here, electrodes are attached to the scalp of participants. What is observed are the changes in electrical activity in the brain during sleep ( the machine is called an EEG ).

Controlled observations are usually overt as the researcher explains the research aim to the group so the participants know they are being observed.

Controlled observations are also usually non-participant as the researcher avoids direct contact with the group and keeps a distance (e.g., observing behind a two-way mirror).

Controlled observations can be easily replicated by other researchers by using the same observation schedule. This means it is easy to test for reliability .
The data obtained from structured observations is easier and quicker to analyze as it is quantitative (i.e., numerical) – making this a less time-consuming method compared to naturalistic observations.
Controlled observations are fairly quick to conduct which means that many observations can take place within a short amount of time. This means a large sample can be obtained, resulting in the findings being representative and having the ability to be generalized to a large population.

Limitations

Controlled observations can lack validity due to the Hawthorne effect /demand characteristics. When participants know they are being watched, they may act differently.

Naturalistic Observation

Naturalistic observation is a research method in which the researcher studies behavior in its natural setting without intervention or manipulation.

It involves observing and recording behavior as it naturally occurs, providing insights into real-life behaviors and interactions in their natural context.

Naturalistic observation is a research method commonly used by psychologists and other social scientists.

This technique involves observing and studying the spontaneous behavior of participants in natural surroundings. The researcher simply records what they see in whatever way they can.

In unstructured observations, the researcher records all relevant behavior with a coding system. There may be too much to record, and the behaviors recorded may not necessarily be the most important, so the approach is usually used as a pilot study to see what type of behaviors would be recorded.

Compared with controlled observations, it is like the difference between studying wild animals in a zoo and studying them in their natural habitat.

With regard to human subjects, Margaret Mead used this method to research the way of life of different tribes living on islands in the South Pacific. Kathy Sylva used it to study children at play by observing their behavior in a playgroup in Oxfordshire.

Collecting Naturalistic Behavioral Data

Technological advances are enabling new, unobtrusive ways of collecting naturalistic behavioral data.

The Electronically Activated Recorder (EAR) is a digital recording device participants can wear to periodically sample ambient sounds, allowing representative sampling of daily experiences (Mehl et al., 2012).

Studies program EARs to record 30-50 second sound snippets multiple times per hour. Although coding the recordings requires extensive resources, EARs can capture spontaneous behaviors like arguments or laughter.

EARs minimize participant reactivity since sampling occurs outside of awareness. This reduces the Hawthorne effect, where people change behavior when observed.

The SenseCam is another wearable device that passively captures images documenting daily activities. Though primarily used in memory research currently (Smith et al., 2014), systematic sampling of environments and behaviors via the SenseCam could enable innovative psychological studies in the future.

By being able to observe the flow of behavior in its own setting, studies have greater ecological validity.
Like case studies , naturalistic observation is often used to generate new ideas. Because it gives the researcher the opportunity to study the total situation, it often suggests avenues of inquiry not thought of before.
The ability to capture actual behaviors as they unfold in real-time, analyze sequential patterns of interactions, measure base rates of behaviors, and examine socially undesirable or complex behaviors that people may not self-report accurately.
These observations are often conducted on a micro (small) scale and may lack a representative sample (biased in relation to age, gender, social class, or ethnicity). This may result in the findings lacking the ability to generalize to wider society.
Natural observations are less reliable as other variables cannot be controlled. This makes it difficult for another researcher to repeat the study in exactly the same way.
Highly time-consuming and resource-intensive during the data coding phase (e.g., training coders, maintaining inter-rater reliability, preventing judgment drift).
With observations, we do not have manipulations of variables (or control over extraneous variables), meaning cause-and-effect relationships cannot be established.

Participant Observation

Participant observation is a variant of the above (natural observations) but here, the researcher joins in and becomes part of the group they are studying to get a deeper insight into their lives.

If it were research on animals , we would now not only be studying them in their natural habitat but be living alongside them as well!

Leon Festinger used this approach in a famous study into a religious cult that believed that the end of the world was about to occur. He joined the cult and studied how they reacted when the prophecy did not come true.

Participant observations can be either covert or overt. Covert is where the study is carried out “undercover.” The researcher’s real identity and purpose are kept concealed from the group being studied.

The researcher takes a false identity and role, usually posing as a genuine member of the group.

On the other hand, overt is where the researcher reveals his or her true identity and purpose to the group and asks permission to observe.

It can be difficult to get time/privacy for recording. For example, researchers can’t take notes openly with covert observations as this would blow their cover. This means they must wait until they are alone and rely on their memory. This is a problem as they may forget details and are unlikely to remember direct quotations.
If the researcher becomes too involved, they may lose objectivity and become biased. There is always the danger that we will “see” what we expect (or want) to see. This problem is because they could selectively report information instead of noting everything they observe. Thus reducing the validity of their data.

Recording of Data

With controlled/structured observation studies, an important decision the researcher has to make is how to classify and record the data. Usually, this will involve a method of sampling.

In most coding systems, codes or ratings are made either per behavioral event or per specified time interval (Bakeman & Quera, 2011).

The three main sampling methods are:

Event-based coding involves identifying and segmenting interactions into meaningful events rather than timed units.

For example, parent-child interactions may be segmented into control or teaching events to code. Interval recording involves dividing interactions into fixed time intervals (e.g., 6-15 seconds) and coding behaviors within each interval (Bakeman & Quera, 2011).

Event recording allows counting event frequency and sequencing while also potentially capturing event duration through timed-event recording. This provides information on time spent on behaviors.

Coding Systems

The coding system should focus on behaviors, patterns, individual characteristics, or relationship qualities that are relevant to the theory guiding the study (Wampler & Harper, 2014).

Codes vary in how much inference is required, from concrete observable behaviors like frequency of eye contact to more abstract concepts like degree of rapport between a therapist and client (Hill & Lambert, 2004). More inference may reduce reliability.

Macroanalytic coding systems

Macroanalytic coding systems involve rating or summarizing behaviors using larger coding units and broader categories that reflect patterns across longer periods of interaction rather than coding small or discrete behavioral acts.

For example, a macroanalytic coding system may rate the overall degree of therapist warmth or level of client engagement globally for an entire therapy session, requiring the coders to summarize and infer these constructs across the interaction rather than coding smaller behavioral units.

These systems require observers to make more inferences (more time-consuming) but can better capture contextual factors, stability over time, and the interdependent nature of behaviors (Carlson & Grotevant, 1987).

Microanalytic coding systems

Microanalytic coding systems involve rating behaviors using smaller, more discrete coding units and categories.

For example, a microanalytic system may code each instance of eye contact or head nodding during a therapy session. These systems code specific, molecular behaviors as they occur moment-to-moment rather than summarizing actions over longer periods.

Microanalytic systems require less inference from coders and allow for analysis of behavioral contingencies and sequential interactions between therapist and client. However, they are more time-consuming and expensive to implement than macroanalytic approaches.

Mesoanalytic coding systems

Mesoanalytic coding systems attempt to balance macro- and micro-analytic approaches.

In contrast to macroanalytic systems that summarize behaviors in larger chunks, mesoanalytic systems use medium-sized coding units that target more specific behaviors or interaction sequences (Bakeman & Quera, 2017).

For example, a mesoanalytic system may code each instance of a particular type of therapist statement or client emotional expression. However, mesoanalytic systems still use larger units than microanalytic approaches coding every speech onset/offset.

The goal of balancing specificity and feasibility makes mesoanalytic systems well-suited for many research questions (Morris et al., 2014). Mesoanalytic codes can preserve some sequential information while remaining efficient enough for studies with adequate but limited resources.

For instance, a mesoanalytic couple interaction coding system could target key behavior patterns like validation sequences without coding turn-by-turn speech.

In this way, mesoanalytic coding allows reasonable reliability and specificity without requiring extensive training or observation. The mid-level focus offers a pragmatic compromise between depth and breadth in analyzing interactions.

Preventing Coder Drift

Coder drift results in a measurement error caused by gradual shifts in how observations get rated according to operational definitions, especially when behavioral codes are not clearly specified.

This type of error creeps in when coders fail to regularly review what precise observations constitute or do not constitute the behaviors being measured.

Preventing drift refers to taking active steps to maintain consistency and minimize changes or deviations in how coders rate or evaluate behaviors over time. Specifically, some key ways to prevent coder drift include:

Operationalize codes : It is essential that code definitions unambiguously distinguish what interactions represent instances of each coded behavior.
Ongoing training : Returning to those operational definitions through ongoing training serves to recalibrate coder interpretations and reinforce accurate recognition. Having regular “check-in” sessions where coders practice coding the same interactions allows monitoring that they continue applying codes reliably without gradual shifts in interpretation.
Using reference videos : Coders periodically coding the same “gold standard” reference videos anchors their judgments and calibrate against original training. Without periodic anchoring to original specifications, coder decisions tend to drift from initial measurement reliability.
Assessing inter-rater reliability : Statistical tracking that coders maintain high levels of agreement over the course of a study, not just at the start, flags any declines indicating drift. Sustaining inter-rater agreement requires mitigating this common tendency for observer judgment change during intensive, long-term coding tasks.
Recalibrating through discussion : Having meetings for coders to discuss disagreements openly explores reasons judgment shifts may be occurring over time. Consensus on the application of codes is restored.
Adjusting unclear codes : If reliability issues persist, revisiting and refining ambiguous code definitions or anchors can eliminate inconsistencies arising from coder confusion.

Essentially, the goal of preventing coder drift is maintaining standardization and minimizing unintentional biases that may slowly alter how observational data gets rated over periods of extensive coding.

Through the upkeep of skills, continuing calibration to benchmarks, and monitoring consistency, researchers can notice and correct for any creeping changes in coder decision-making over time.

Reducing Observer Bias

Observational research is prone to observer biases resulting from coders’ subjective perspectives shaping the interpretation of complex interactions (Burghardt et al., 2012). When coding, personal expectations may unconsciously influence judgments. However, rigorous methods exist to reduce such bias.

Coding Manual

A detailed coding manual minimizes subjectivity by clearly defining what behaviors and interaction dynamics observers should code (Bakeman & Quera, 2011).

High-quality manuals have strong theoretical and empirical grounding, laying out explicit coding procedures and providing rich behavioral examples to anchor code definitions (Lindahl, 2001).

Clear delineation of the frequency, intensity, duration, and type of behaviors constituting each code facilitates reliable judgments and reduces ambiguity for coders. Application risks inconsistency across raters without clarity on how codes translate to observable interaction.

Coder Training

Competent coders require both interpersonal perceptiveness and scientific rigor (Wampler & Harper, 2014). Training thoroughly reviews the theoretical basis for coded constructs and teaches the coding system itself.

Multiple “gold standard” criterion videos demonstrate code ranges that trainees independently apply. Coders then meet weekly to establish reliability of 80% or higher agreement both among themselves and with master criterion coding (Hill & Lambert, 2004).

Ongoing training manages coder drift over time. Revisions to unclear codes may also improve reliability. Both careful selection and investment in rigorous training increase quality control.

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Open access
Published: 22 April 2024

Perioperative serum syndecan-1 concentrations in patients who underwent cardiovascular surgery with cardiopulmonary bypass and its association with the occurrence of postoperative acute kidney injury: a retrospective observational study

Atsushi Miyazaki 1 ,
Mai Hokka 1 ,
Norihiko Obata 1 &
Satoshi Mizobuchi 1

BMC Anesthesiology volume 24 , Article number: 154 ( 2024 ) Cite this article

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Various factors can cause vascular endothelial damage during cardiovascular surgery (CVS) with cardiopulmonary bypass (CPB), which has been suggested to be associated with postoperative complications. However, few studies have specifically investigated the relationship between the degree of vascular endothelial damage and postoperative acute kidney injury (pAKI).

The objectives of this study were to measure perioperative serum syndecan-1 concentrations in patients who underwent CVS with CPB, evaluate their trends, and determine their association with pAKI.

This was a descriptive and case‒control study conducted at the National University Hospital. Adult patients who underwent CVS with CPB at a national university hospital between March 15, 2016, and August 31, 2020, were included. Patients who were undergoing preoperative dialysis, had preoperative serum creatinine concentrations greater than 2.0 mg dl −1 , who were undergoing surgery involving the descending aorta were excluded. The perioperative serum syndecan-1 concentration was measured, and its association with pAKI was investigated.

Fifty-two patients were included. pAKI occurred in 18 (34.6%) of those patients. The serum syndecan-1 concentration increased after CPB initiation and exhibited bimodal peak values. The serum syndecan-1 concentration at all time points was significantly elevated compared to that after the induction of anesthesia. The serum syndecan-1 concentration at 30 min after weaning from CPB and on postoperative day 1 was associated with the occurrence of pAKI (OR = 1.10 [1.01 to 1.21], P = 0.03]; OR = 1.16 [1.01 to 1.34], P = 0.04]; and the cutoff values of the serum syndecan-1 concentration that resulted in pAKI were 101.0 ng ml −1 (sensitivity = 0.71, specificity = 0.62, area under the curve (AUC) = 0.67 (0.51 to 0.83)) and 57.1 ng ml −1 (sensitivity = 0.82, specificity = 0.56, AUC = 0.71 (0.57 to 0.86)). Multivariate logistic regression analysis revealed that the serum syndecan-1 concentration on postoperative day 1 was associated with the occurrence of pAKI (OR = 1.02 [1.00 to 1.03]; P = 0.03).

The serum syndecan-1 concentration at all time points was significantly greater than that after the induction of anesthesia. The serum syndecan-1 concentration on postoperative day 1 was significantly associated with the occurrence of pAKI.

Trial registration

This study is not a clinical trial and is not registered with the registry.

Peer Review reports

Various postoperative complications can lead to increased mortality in patients receiving cardiovascular surgery (CVS) with cardiopulmonary bypass (CPB). Postoperative AKI (pAKI) is an important complication that occurs in 5–30% of patients undergoing CVS, and even small increases in serum creatinine concentrations have been reported to lead to increased mortality [ 1 ]. Recently, it has been suggested that management with goal-directed perfusion focusing on oxygen supply during CPB period may reduce the incidence of pAKI, but pAKI is multifactorial [ 2 ] and there is no established prevention protocol. Vascular endothelial damage is thought to be one of the causes of pAKI [ 3 , 4 , 5 ]. Rehm et al. reported that the vascular endothelium in patients undergoing CVS is easily destroyed due to inflammation induced by CPB, aortic occlusion, and ischemia–reperfusion injury [ 6 ]. In addition, it has been reported that the vascular endothelial glycocalyx, which is present on the surface of vascular endothelial cells, is fragile and sheds when subjected to invasive stresses such as CVS, leading to increased plasma concentrations of vascular endothelial glycocalyx components such as syndecan-1 [ 7 ]. Although previous studies have investigated the association between preoperative or postoperative serum syndecan-1 concentrations and pAKI, few studies have examined perioperative serum syndecan-1 levels and investigated the association with pAKI. In the present study, we hypothesized that the perioperative serum syndecan-1 concentration is associated with pAKI. The objectives of this study were to examine the perioperative trends in the serum syndecan-1 concentration in adult patients receiving CVS via CPB and to clarify the association between vascular endothelial damage and the occurrence of pAKI.

This was a single-center, retrospective, descriptive study performed to investigate the perioperative serum syndecan-1 concentration in patients who underwent CVS with CPB. This study was conducted using samples stored in a previous study [ 8 ].

Ethical approval for this study was provided by the Kobe University Graduate School of Medicine, Medical Ethics Committee (Chairperson Prof. Makoto Nakamura, approval number: B220044) on June 21, 2022.

A trained researcher collected the data and entered the information into a database. Data monitoring and source-data verification were conducted in accordance with a predefined plan. Due to the retrospective nature of the study, the need for informed consent was waived by the ethical committee. Instead, the researchers made appropriate disclosures about the study and provided the participants with the opportunity to refuse enrollment in the study.

Setting and participants

Adult patients who underwent CVS with CPB at a national university hospital between March 15, 2016, and August 31, 2020, were included in this study. Patients who were undergoing preoperative dialysis, had preoperative serum creatinine concentrations greater than 2.0 mg dl −1 , or who were undergoing surgery involving the descending aorta were excluded.

Patient characteristics

The following patient characteristics were obtained: age, sex, weight, height, ASA-PS, European System for Cardiac Operative Risk Evaluation II, presence of hypertension and diabetes mellitus, preoperative left ventricular ejection fraction (LVEF), and estimated glomerular filtration rate (eGFR). Surgical information, including operation time, aortic cross-clamp time, duration of CPB, type of procedure, and amount of transfusion during surgery, was also obtained.

Measurements of the serum syndecan-1 concentration

Serum syndecan-1 concentrations were measured at the following six time points: (T1) after induction of anesthesia, (T2) 1 h after initiation of CPB, (T3) 2 h after initiation of CPB, (T4) 30 min after weaning from CPB, (T5) 2 h after weaning from CPB, and (T6) postoperative day 1 (Fig. 1 ). The serum syndecan-1 concentration was measured using an enzyme-linked immunosorbent assay (ELISA) kit (Human CD138 ELISA Kit, Diaclone SAS, France). To prevent observer bias, the serum syndecan-1 concentration was measured by a third party not involved in the study.

Serum syndecan-1 concentration was measured at each time point. The serum syndecan-1 concentration was measured at the following 6 time points: T1) after anesthesia induction, T2) 1 h after initiation of CPB, T3) 2 h after initiation of CPB, T4) 30 min after weaning from CPB, T5) 2 h after weaning from CPB, and T6) on postoperative day 1

Anesthesia methods

Anesthesia was administered by the anesthesiologist in charge. At the facility where this study was conducted, 500 mg of methylprednisolone was administered before starting CPB. Heparin was used as an anticoagulant to control the activated clotting time for more than 400 s, and protamine was administered as a heparin antagonist when hemostasis was confirmed after weaning from CPB. The choice of the type and amount of transfusion and inotropic agent also depended on the anesthesiologist in charge.

CPB management

Several trained perfusionists controlled the circulatory dynamics during CPB period.

During the CPB procedure, the cardiac index was managed with the target of 2.4–2.6 L/min/m 2 , and oxygen delivery (DO 2 ) and oxygen consumption (VO 2 ) were monitored as needed.

Study outcomes

The primary outcome was the change in the perioperative serum syndecan-1 concentration. The secondary outcome was the association between the perioperative serum syndecan-1 concentration and pAKI incidence. The diagnosis of pAKI was based on the Kidney Disease Improving Global Outcomes classification system. Although AKI was defined as an increase in the serum creatinine concentration and a decrease in urine output, the authors decided not to adopt the criterion of urine output for the definition of AKI in the present study to avoid the influence of the use of a diuretic drug in patients.

Statistical analysis

All variables are expressed as medians 〔IQRs〕 or means ± SDs. First, the perioperative serum syndecan-1 concentrations were graphically plotted for all patients, and the serum syndecan-1 concentration at each measurement point were compared to that at T1. Comparisons between each measurement point were performed using the Mann‒Whitney U test. The patients were then divided into groups according to the presence or absence of pAKI, and the perioperative serum syndecan-1 concentration was graphically plotted for each group and compared at each time point. Comparisons between two groups were performed using the Mann‒Whitney U test. If the CPB duration was less than 2 h, the serum syndecan-1 concentration at T3 was not measured, and statistical analysis was performed only for those who had data.

A single regression analysis was performed to examine the association between serum syndecan-1 (syndecan-1/10) concentrations and pAKI at each time point. At the time points at which significant differences were detected in the single regression analysis, receiver operating characteristic (ROC) curve analysis was performed to estimate the cutoff value.

The χ2 test was used to analyze whether a serum syndecan-1 concentration above or below the cutoff value had an effect on the occurrence of pAKI.

Finally, multivariate logistic regression analysis was performed to evaluate the association between the serum syndecan-1 concentration and pAKI incidence. No statistical analysis for sample size determination was performed in this study, and a P value < 0.05 was considered to indicate a statistically significant difference. Statistical analysis was performed using SigmaPlot 14.5 (SYSTAT software, CA, United States).

Fifty-two patients who underwent CVS with CPB were included. pAKI occurred in 18 (34.6%) of those patients. Stage 1 and Stage 2 were 15 and 3, respectively.

Patient demographic characteristics

Table 1 shows a comparison of the demographic data of the patients with and without pAKI. There were more male patients with pAKI than female patients ( P = 0.01), and patients with AKI had a lower preoperative eGFR ( P = 0.02) than did those without pAKI. There were no significant differences between the two groups with respect to the other demographic parameters.

Changes in the serum syndecan-1 concentration

Figure 2 shows the perioperative changes in the serum syndecan-1 concentration. Six patients with a CPB duration of less than 2 h did not have a serum syndecan-1 measurement at T3. It began to increase with the initiation of CPB and then reached a bimodal peak value. The serum syndecan-1 concentration at all time points was significantly elevated compared to that at T1.

Perioperative serum syndecan-1 concentration. Shows the perioperative serum syndecan-1 concentrations at each time point. Serum syndecan-1 concentrations at all time points were significantly elevated compared to those at T1. * P < 0.05

Comparison of the serum syndecan-1 concentration between patients with and without pAKI

Figure 3 shows a comparison of perioperative serum syndecan-1 concentrations between patients with and without pAKI. Before and after weaning from CPB, the serum syndecan-1 concentration was not significantly different between the two groups, whereas there was a significant difference at T6 (patients with pAKI 97.1 〔73.5 to 127.2〕 ng ml −1 and patients without pAKI 53.3 〔38.7 to 74.4〕 ng ml −1 ( P < 0.01)). Table 2 shows the ORs and 95% CIs from the single logistic regressions of pAKI occurrence according to the serum syndecan-1 concentration at each time point. Serum syndecan-1 concentrations at T4 and T6 were associated with an increased risk of pAKI (T4: OR = 1.10 [1.01 to 1.21, P = 0.03]; T6: OR = 1.16 [1.01 to 1.34, P = 0.04]). To calculate the cutoff value for the occurrence of pAKI, ROC analysis was performed for the serum syndecan-1 concentrations at T4 and T6. The estimated cutoff value was 101.0 ng ml −1 (sensitivity: 0.71; specificity: 0.62; area under the curve (AUC) = 0.67 (0.51 to 0.83)) at T4 and 57.1 ng ml −1 (sensitivity: 0.82; specificity: 0.56; AUC = 0.71 (0.57 to 0.86)) at T6 (Fig. 4 ). To analyze whether this cutoff value was significantly associated with the development of AKI, a χ2 test was performed. The cutoff value at T4 was not significantly associated with the occurrence of pAKI (χ2 (1) = 0.34, P = 0.56), whereas the cutoff value at T6 was significantly associated with the occurrence of pAKI (χ2 (1) = 4.55, P = 0.03). Finally, to evaluate the association between the serum syndecan-1 concentration at T6 and the occurrence of pAKI, multivariable logistic regression was conducted to control for the potentially confounding effects that are thought to be associated with pAKI (age, CPB duration, preoperative estimated glomerular filtration rate (eGFR)) and the serum syndecan-1 concentration at T6. Table 3 shows the ORs and 95% CIs from logistic regressions of pAKI occurrence adjusted for patient and setting characteristics, as described above. A high serum syndecan-1 concentration at T6 was associated with the occurrence of pAKI (OR = 1.02 (1.00 to 1.03), P = 0.03).

Comparisons of perioperative serum syndecan-1 concentrations in patients with and without pAKI. Shows a comparison of the perioperative serum syndecan-1 concentrations between patients with and without pAKI at the 6 time points. The white box plots indicate values for patients without pAKI, and the black box plots indicate values for patients with pAKI. * P < 0.05

ROC curves of the serum syndecan-1 concentration at T4 and T6 for the prediction of pAKI. The black line represents the ROC curve for T4, and the red line represents that for T6

In this study, we investigated the perioperative serum syndecan-1 concentration in patients who underwent CVS with CPB as an indicator of vascular endothelial damage and evaluated its impact on pAKI. The serum syndecan-1 concentration began to increase after the initiation of CPB and then exhibited a bimodal peak. Serum syndecan-1 concentrations at all time points were significantly elevated compared to those at T1. Simple linear regression analysis revealed that the serum syndecan-1 concentration at T4 and T6 influenced the occurrence of pAKI. The estimated cutoff values were 101.0 ng ml −1 and 57.1 ng ml −1 , respectively. The cutoff value of the serum syndecan-1 concentration at T6 was also shown to independently influence pAKI occurrence according to the χ2 test. The results of logistic regression analysis adjusted for covariates thought to be associated with the occurrence of pAKI also indicated that the serum syndecan-1 concentration at T6 was associated with pAKI.

The glycocalyx is a complex consisting of a core protein that penetrates vascular endothelial cells, glycosaminoglycans, hyaluronic acid, and other sugar chains [ 1 ]. The vascular endothelial glycocalyx has various physiological functions, including regulating vascular permeability, regulating leukocyte migration, and inhibiting thrombosis [ 9 , 10 ]. Syndecan-1 is a core protein of the glycocalyx. When the glycocalyx is disrupted and detached from the vascular endothelium, the blood concentration of syndecan-1 increases, indirectly providing an estimate of the degree of glycocalyx disruption [ 11 ].

Several studies have shown that various factors associated with CVS, such as sympathetic hyperactivity, ischemia–reperfusion injury, induction of inflammatory conditions, and volume overload, can cause vascular endothelial cell injury [ 12 , 13 , 14 ]. Bruegger et al. measured the intraoperative serum syndecan-1 concentration in patients who underwent on-pump or off-pump coronary artery bypass grafting (CABG). In the on-pump CABG group, the serum syndecan-1 concentration increased twofold above the baseline level at the time of aortic occlusion release and further increased at weaning from CPB. On the other hand, a significant increase in the serum syndecan-1 concentration was also observed in the off-pump CABG group at the end of central anastomosis [ 15 ]. Rehm et al. showed trends in the serum syndecan-1 concentration during ascending aortic replacement surgery involving CPB and abdominal aortic replacement surgery involving aortic occlusion. The serum syndecan-1 concentration increased by 65-fold above the preoperative level 2 min before weaning from CPB during ascending aortic replacement surgery and increased 15-fold above the preoperative level 15 min after the withdrawal of aortic occlusion during abdominal aortic replacement surgery [ 16 ]. He et al. measured the perioperative serum syndecan-1 concentration in patients who underwent CVS with CPB. The serum syndecan-1 concentration began to increase within 10 min after CPB initiation and peaked when the aortic occlusion was released [ 17 ]. In previous studies, the serum syndecan-1 concentration during CPB peaked at the time of weaning from CPB and then rapidly declined due to rapid metabolism from the kidneys [ 5 ]. In contrast, in the present study, the serum syndecan-1 concentration temporarily decreased at 30 min after weaning from CPB and then increased again. There are several possible reasons for this discrepancy. First, in the present study, the duration of CPB and aortic occlusion was longer than that in previous studies, and the longer duration of CPB and aortic occlusion may have resulted in greater damage to the vascular endothelium. Second, massive infusions have been reported to cause glycocalyx disorders by promoting the release of ANP [ 13 , 14 ]. Although the present study had insufficient data on blood transfusions after weaning from CPB, excessive infusion may be associated with glycocalyx disorders.

In the present study, there was a significant difference in the serum syndecan-1 concentration between the pAKI group and non pAKI group at T6. Univariate analysis revealed that serum syndecan-1 concentrations at T4 and T6 were associated with pAKI. Several studies have investigated the relationship between vascular endothelial damage and pAKI in patients with CVS. Saqib H. Qureshi et al. used porcine models to compare a group undergoing surgery with CPB and a group undergoing sham surgery to examine the effects of CPB on renal dysfunction, and they analyzed the effects of CPB on renal vascular endothelial cells using immunofluorescence probing. In their study, there was a significant reduction in creatinine clearance in Porcinis patients who underwent surgery with CPB. In addition, immunofluorescence probing revealed a significant decrease in glycosaminoglycan, a component of the glycocalyx, in renal vascular endothelial cells from porcine patients who underwent surgery with CPB compared to those who underwent a sham operation [ 3 ]. Several studies have also been conducted on humans. De Melo Bezerra Cavalcante et al. reported an association between early postoperative serum syndecan-1 concentrations and pAKI in children undergoing CVS. Their results showed that a decrease in the serum syndecan-1 concentration within 2 h after surgery was associated with the occurrence of pAKI. They also reported that the cutoff value of the serum syndecan-1 concentration that predicts the development of severe AKI (KDIGO stage 2 or 3) was 66.4 ng mL −1 [ 4 ]. Kim et al. measured the serum syndecan-1 concentration at the induction of anesthesia and at weaning from CPB in patients undergoing valvular surgery and analyzed the association between the serum syndecan-1 concentration and pAKI incidence. They found that a serum syndecan-1 concentration > 90 ng ml −1 at induction of anesthesia was associated with an increased risk of pAKI [ 5 ]. While these studies have shown an association between preoperative or postoperative serum syndecan-1 concentrations and the occurrence of pAKI, little is known about the association between serum syndecan-1 concentrations measured throughout the perioperative period and the occurrence of pAKI. The present study differs from previous studies in that the perioperative serum syndecan-1 concentration was frequently measured to determine the trends and associations of these changes with the occurrence of pAKI.

This study has several limitations. First, since this was a small, single-center study, it is not clear whether this is true for all races, and further data validation in patients with the same background is needed to determine whether the cutoff values derived from this study are correct. Second, patients with preexisting renal dysfunction (serum creatinine level ≥ 2 mg dl −1 ) were excluded from the study. This may also explain why no difference in the baseline serum syndecan-1 concentration was found . However, whether the results of the present study apply to patients with chronic renal failure is unknown and requires further investigation. Third,

The trends in the perioperative serum syndecan-1 concentration and its association with the occurrence of pAKI in patients undergoing CVS with CPB were investigated. The serum syndecan-1 concentration began to increase after the initiation of CPB and then exhibited a bimodal peak. The serum syndecan-1 concentration at all time points was significantly elevated compared to that after the induction of anesthesia. The serum syndecan-1 concentration on postoperative day 1 was associated with the occurrence of pAKI. The estimated cutoff value was 57.1 ng ml −1 (sensitivity = 0.82, specificity = 0.56, AUC = 0.71 (0.57 to 0.86)). Multivariate analysis revealed that the serum syndecan-1 concentration on postoperative day 1 was associated with the occurrence of pAKI.

Availability of data and materials

The datasets used and/or analyzed during the current study are available from the corresponding author upon reasonable request.

Abbreviations

Cardiovascular surgery

Cardiopulmonary bypass

Postoperative acute kidney injury

European System for Cardiac Operative Risk Evaluation II

Estimated glomerular filtration rate

Left ventricular ejection fraction

Red cell concentrate

Flesh frozen plasma

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Acknowledgements

We would like to express our gratitude to Dr. Moritoki Egi, the professor of the Department of Anesthesia, Kyoto University Hospital, for his support from the conceptual stage in carrying out this study and to Miho Kimura, a researcher in the Division of Anesthesiology, Department of Surgery Related, Kobe University Graduate School of Medicine, for her assistance with the syndecan-1 measurements.

This work was supported by JSPS KAKENHI (grant number 20K17781).

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AM performed the statistical analysis and drafted the work. MH substantively revised the work and was a major contributor to the writing of the manuscript. NO has interpreted the data. SM made substantial contributions to the conception of the study. All the authors read and approved the final manuscript.

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Correspondence to Mai Hokka .

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Ethical approval for this study was provided by the Ethical Committee on June 21, 2022. Due to the retrospective nature of the study, the need for informed consent was waived by the ethical committee.

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Miyazaki, A., Hokka, M., Obata, N. et al. Perioperative serum syndecan-1 concentrations in patients who underwent cardiovascular surgery with cardiopulmonary bypass and its association with the occurrence of postoperative acute kidney injury: a retrospective observational study. BMC Anesthesiol 24 , 154 (2024). https://doi.org/10.1186/s12871-024-02546-1

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DOI : https://doi.org/10.1186/s12871-024-02546-1

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Appropriate use of medication among home care adult cancer patients at end of life: a retrospective observational study

Amani El Mughrabi 1 ,
Sewar S. Salmany 1 ,
Batool Aljarrat 2 ,
Ala’a Dabbous 1 &
Haya Ayyalawwad 3

BMC Palliative Care volume 23 , Article number: 108 ( 2024 ) Cite this article

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Medications are commonly used for symptom control in cancer patients at the end of life. This study aimed to evaluate medication utilization among home care palliative patients with cancer at the end of life and assess the appropriateness of these medications.

This retrospective observational study included adult cancer patients who received home care in 2020. Medications taken during the last month of the patient’s life were reviewed and classified into three major categories: potentially avoidable, defined as medications that usually have no place at the end of life because the time to benefit is shorter than life expectancy; medications of uncertain appropriateness, defined as medications that need case-by-case evaluation because they could have a role at the end of life; and potentially appropriate, defined as medications that provide symptomatic relief.

In our study, we enrolled 353 patients, and 2707 medications were analyzed for appropriateness. Among those, 1712 (63.2%) were classified as potentially appropriate, 755 (27.9%) as potentially avoidable, and 240 (8.9%) as medications with uncertain appropriateness. The most common potentially avoidable medications were medications for peptic ulcers and gastroesophageal reflux disease (30.5%), vitamins (14.6%), beta-blockers (9.8%), anticoagulants (7.9%), oral antidiabetics (5.4%) and insulin products (5.3%). Among the potentially appropriate medications, opioid analgesics were the most frequently utilized medications (19.5%), followed by laxatives (19%), nonopioid analgesics (14.4%), gamma-aminobutyric acid analog analgesics (7.7%) and systemic corticosteroids (6%).

In home care cancer patients, approximately one-third of prescribed medications were considered potentially avoidable. Future measures to optimize medication use in this patient population are essential.

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Introduction

Palliative care is ‘‘an approach that improves quality of life of patients and their families who are facing problems associated with life-threatening illness. It prevents and relieves suffering through early identification, correct assessment, and treatment of pain and other problems, whether physical, psychosocial or spiritual” [ 1 ]. This care should be provided soon after a patient is diagnosed with cancer, even before approaching the end stage of cancer. Providing palliative care in the home setting remains the best approach for reducing symptom burdens and increasing satisfaction for both patients and their families. Additionally, it leads to a decrease in healthcare resource utilization and costs [ 2 , 3 , 4 ].

At the end of life, patients often require intensive medication assessment for both chronic conditions and symptoms associated with end-stage disease, both for cancer and noncancer patients [ 5 ]. Medications for disease prevention have limited value since the duration of therapeutic benefit is longer than the estimated life expectancy, and such medications should be discontinued [ 6 , 7 ]. As a patient approaches the end of life, the goal of care shifts from curative intent to symptomatic palliative intent, necessitating the discontinuation of unnecessary chronic medications. However, this practice is not commonly observed, as it leads to an increased risk of polypharmacy and associated adverse drug events for patients, despite the questionable benefits of some medications [ 8 , 9 ].

The prevalence of avoidable and appropriate medication use among home care patients with cancer at the end of life has not been well described. Previously published studies have described medication use in hospice care units for both cancer and noncancer patients [ 10 , 11 , 12 , 13 ]. However, these studies did not classify medications based on their appropriateness at the end of life [ 11 , 13 ]. Additionally, Sera et al. identified commonly prescribed medications for hospice patients, but their study encompassed various care settings, such as skilled nursing facilities, inpatient hospitals, and inpatient hospice units, rather than specifically focused on patients receiving home care [ 13 ].

The primary objective of this study was to assess medication utilization among home care palliative patients with cancer at the end of life and to evaluate the appropriateness of these medications. The secondary objective was to investigate the associations between total medications and potentially avoidable medications received by home care patients and among several variables in the present study, including palliative performance status (PPS), age, gender, and others.

This study is designed to optimize end of life care of home care cancer patients by avoiding the pursuit of unnecessary medications and enhancing the use of medications targeting symptom management, which improves patients’ quality of life. It also demonstrates the need for establishing a paradigm for developing guidelines for deprescribing potentially avoidable medications in end of life patients which facilitate the decision to discontinue this category of medications.

This retrospective observational study was conducted at King Hussein Cancer Center (KHCC), a comprehensive cancer center in Jordan. The study included adult cancer patients who received home care services between January and December 2020. At KHCC, home care services are provided to cancer patients whose performance status is reduced, preventing them from attending regular hospital follow-ups. This service is provided by a multidisciplinary team, including a physician, nurse, clinical pharmacist, and other disciplines, as necessary. Under home care services, patients may undergo a consultation for symptom management or be referred to palliative care home services after discontinuation of active cancer treatment.

Patients included in our study were those who received home care services during the last month of their life and passed away before December 2020. Patients who declined home care services during the study period were excluded from the study. Patient demographic data, such as age at the time of death, gender, duration of home care services provided, medical history (including type of cancer and comorbidities), medication list, and palliative performance status (PPS), were extracted from the KHCC Computerized Patient Record System (CPRS).

Medications were classified into three main categories based on their purpose for managing chronic conditions or relieving symptoms. The first category comprises potentially avoidable medications. These medications are primarily used for chronic condition management, and their effect at the end of life is typically limited because the time to benefit is shorter than the patient’s life expectancy. The second category includes medications of uncertain appropriateness, which require a case-by-case re-evaluation, as their benefit, particularly in terms of limited life expectancy, is debatable. The third category includes potentially appropriate medications that are used for symptom management. This category includes medications that target common symptoms in palliative care (such as pain, dyspnea, fatigue, terminal respiratory congestion, anxiety, dry mouth, depression, hiccups, delirium, anorexia-cachexia, insomnia, constipation, terminal restlessness, diarrhea, sweating, nausea and vomiting). The classification of medications used in this study was based on previously published studies [ 14 , 15 , 16 , 17 ]. Additionally, the pharmacological categories of medications were determined according to the Up-To-Date online clinical support resource [ 18 ]. Medications were reviewed and classified by pharmacists who have expertise in palliative and hospice care.

The research protocol was reviewed and approved by the Institutional Review Board (IRB) of KHCC with the ethics approval number 21 KHCC 066 on July 15, 2021.

Statistical analysis

A descriptive analysis of patient information was performed. Categorical data, such as gender, type of cancer, comorbidities, PPS, and other factors, are presented as counts and/or percentages. The means, standard deviations (SDs), and medians were calculated for the continuous data, including duration of home care service and age. Univariate analysis was performed to evaluate the associations of different factors in the study with the number of total medications and potentially avoidable medication categories. Mann-Whitney U test was used to test the differences because the data was not normally distributed. Moreover, multivariate analysis was performed for the significant factors by using a general linear model (GLM) for total and avoidable medications. A P value ≤ 0.05 was considered to indicate statistical significance in the analysis. All analyses were performed using SAS software version 9.4 (SAS Institute, Inc., Cary, NC).

The study sample included 353 patients with a median age of 64 years. There were 184 (52%) male patients. Approximately half (161, 45.6%) of the patients had multiple comorbidities; cardiovascular diseases were the most common (114, 46.9%), followed by endocrine diseases (82, 33.7%), respiratory diseases (15, 6.2%), urogenital diseases (11, 4.5%), musculoskeletal disorders (10, 4.1%), mental health diseases (7, 2.9%), gastrointestinal diseases (2, 0.8%), eye- and ear-related diseases (1, 0.4%) and skin-related diseases (1, 0.4%). Of the studied patients, 332 (94.1%) had solid tumors, and 276 (78.2%) had metastatic disease.

The mean (± SD) duration of home care service provided was 44 ± 13.7 days. Among the patients, 219 (62.1%) had a PPS of less than 30, and 118 (33.4%) had a PPS of 40–60. The do not resuscitate (DNR) code was discussed and agreed upon by 117 (33.1%) of the patients.

Overall, 2707 medications were analyzed for their appropriateness. We found that potentially appropriate medications represented 1712 (63.2%) of all medications, followed by potentially avoidable medications 755 (27.9%) and medications of uncertain appropriateness 240 (8.9%).

Among the potentially appropriate medications, the most frequently utilized were opioid analgesics, laxatives, nonopioid analgesics and skeletal muscle relaxants, gamma-aminobutyric acid (GABA) analog analgesics, and systemic corticosteroids (Table 1 ).

We found that among the potentially avoidable medications, medications for peptic ulcers and gastroesophageal reflux were the most frequently used, followed by cardiovascular medication, vitamins and nutritional support, antidiabetic and insulin products and anticoagulants (Table 2 ). Medications with uncertain appropriateness are listed in Table 3 .

Our study showed that patients with comorbidities had a significantly greater mean number of total medications ( P = 0.002) and potentially avoidable medications ( P < 0.001) than those without comorbidities. Additionally, patients with a PPS > 30 had a greater mean number of total medications and potentially avoidable medications than those with a PPS ≤ 30 ( P = 0.029 and P = 0.006, respectively). The mean number of potentially avoidable medications was significantly greater in the 65-year-old and older age groups than in the younger 65-year-old age group. ( P = 0.001). (Table 4 ).

Additionally, the multivariate analysis using general linear model (GLM) regression revealed a statistically significant decrease in the mean number of total medications in patient with a PPS score of ≤ 30 compared to patients with PPS more than 30 and in those who don’t have comorbidities compared with patients with comorbidities by 1.2 ( P = 0.006, 0.004 respectively). The results also showed a statistically significant decrease in the mean number of potentially avoidable medications in patients with a PPS score of ≤ 30, in those who don’t have comorbidities and in patients aged 64 and less by 0.6, 0.8 and 0.6, respectively, ( P = 0.003, 0.001, 0.003 respectively). (Table 5 ).

This is the first study in the Middle East to assess and classify the medications used by home care cancer patients into three categories according to their appropriateness.

Our study showed that a significant percentage of patients’ medications at the end of life were potentially appropriate medications, aligning with the goal of care for patients approaching the end of life. The five most common medications were opioid analgesics; laxatives; nonopioid analgesics, including acetaminophen and nonsteroidal anti-inflammatory drugs (NSAIDs); skeletal muscle relaxants; GABA analog analgesics; and systemic corticosteroids, with dexamethasone being the most frequently utilized corticosteroid. The high percentage of pain medications used is consistent with most literature as pain is one of the most prevalent symptoms among cancer patients at the end of life [ 19 ] and opioid analgesics remain the fundamental medications for cancer-related pain [ 20 ]. Laxatives are frequently prescribed at the time of opioid initiation to prevent opioid-induced constipation, which is a common side effect. Additionally, the high prevalence of constipation in end of life patients could explain the high percentage of laxatives being utilized in our patients [ 21 ].

On the other hand, approximately one-third of patients’ medications were considered potentially avoidable medications. Notably, the most commonly prescribed medications were medications for peptic ulcers and gastroesophageal reflux disease (GERD). Similar findings have been reported in other studies [ 10 , 11 , 12 ]. Overprescribing of Proton pump inhibitors is not uncommon, and it seems overused in end of life cancer patients [ 22 ]. Furthermore, our study revealed that approximately 18% of potentially avoidable medications were cardiovascular medications, including beta blockers and antihypertensive medications, despite their questionable benefits at this stage, because the patient’s life expectancy is not as long as the time to benefit. The use of these classes of medications is common among terminal patients to manage their chronic conditions. Considering the common occurrence of reduced appetite in patients at the end of life, maintaining antihypertensive medications poses the risk of hypotension and falls due to reduced blood pressure readings [ 23 ].

Although the benefit of vitamins and nutritional supplements at the end of life is questionable, their use is not uncommon, despite the potential drawbacks of increased pill burdens and significant drug interactions [ 24 , 25 ]. A study conducted by University Medical Centre Utrecht reviewed homecare patients and revealed that vitamins were utilized by 36% of patients within the last year of life [ 26 ]. Our study showed that vitamins accounted for 15% of potentially avoidable medications in our patient population.

Many barriers to deprescribe potentially avoidable medications have been identified among healthcare professionals. Insufficient knowledge appears to be the main reason. In addition, the lack of consensus evidence-based deprescribing guidelines makes the implementation of deprescribing in the current clinical practice unpractical. Furthermore, the attitudes of both patients and their families towards deprescribing can be challenging [ 27 , 28 ].

Our findings that potentially appropriate medications were much more commonly prescribed than potentially avoidable medications at the end of life are similar to the findings of prior studies of home care patients. Sera et al. [ 13 ] reported that opioid and nonopioid analgesics, anxiolytics, anticholinergics, and antipsychotics were prescribed to more than 60% of patients. Other frequently prescribed symptom medication classes included laxatives, bronchodilators, and antidepressants. Another study conducted by Pasina et al. [ 10 ] to assess the utilization of avoidable and symptomatic medications among end of life patients living at home revealed that all patients received symptomatic medications, with opioids being the most commonly prescribed, followed by systemic corticosteroids, anxiolytics, and antipsychotics. This high percentage of potentially appropriate medications is not surprising, given that cancer patients at the end of their lives experience a wide range of physical and psychological symptoms, including pain, dyspnea, agitation, etc., and that these symptoms worsen as death approaches [ 29 ].

The aforementioned studies concluded that hospice admission was associated with a reduction in the use of commonly prescribed avoidable medications. Furthermore, approximately half of the patients were treated with avoidable medications, with the most frequently prescribed medications being medications for peptic ulcers and GERD and antithrombotic medications.

In our study, we explored the factors associated with the number of total medications and potentially avoidable medications. The multivariate analysis using the GLM showed that patients with a PPS score ≤ 30, patients with no comorbidities are associated with a decrease in the mean number of total medications. Patients with a PPS score ≤ 30, do not have comorbidities and patients with age 64 and less are associated with a decrease in the mean number of potentially avoidable medications. These findings highlight the importance of considering these variables when assessing patients, as they can inform tailored interventions aimed at enhancing medication management for home care cancer patients. This approach not only help in identifying patients who may benefit from a comprehensive medication review to identify avoidable medications but also facilitates the application of deprescribing guidelines and thereby optimizing treatment regimens to improve patient outcomes.

A strength of this study is that it is the first to assess medication utilization among home care palliative patients with cancer at the end of life in the Middle East. Additionally, it investigated the significant factors associated with medications used, such as PPS, age, and comorbidities. This could inform prioritization strategies for medication reviews and deprescribing potentially avoidable medications. Furthermore, the retrospective design of the study enables us to review the present clinical practice of deprescribing potentially avoidable medications in home care patients at end of life.

This study is subject to a few limitations. First, this was a retrospective study, and we could not assess the reasons behind patients continuing to use avoidable medications. The study did not investigate whether this was influenced by patient and family perceptions of deprescribing or if it was due to healthcare providers’ lack of knowledge about deprescribing at the end of life. Second, the study did not involve an assessment of the palliative prognostic index (PPI), a tool utilized by palliative care practitioners to assess life expectancy and guide decisions on deprescribing.

Future prospective studies are warranted to further evaluate prescribing patterns among home care patients at the end of life. In addition, future measures should be implemented to optimize medication use in this patient population and develop clinical practice guidelines to aid in achieving these goals.

Conclusions

Approximately one-third of the medications utilized by patients receiving home care are classified as potentially avoidable medications. To optimize prescribing patterns in this patient setting, several measures could be considered. These measures include creating guidelines for deprescribing potentially avoidable medications to end of life patients, encouraging interdisciplinary discussions, and engaging patients and their families in the decision to discontinue this category of medication to optimize drug use within this patient population.

Data availability

The corresponding author can provide the database created and used in the study upon reasonable request.

Abbreviations

Palliative Performance Status

King Hussein Cancer Center

Computerized Patient Record System

Institutional Review Board

General linear model

Don’t Resuscitate

Gamma-aminobutyric acid

Nonsteroidal anti-inflammatory drugs

Gastroesophageal Reflux Disease

Palliative Prognostic Index

Standard deviation

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Acknowledgements

The authors thank Ayat Taqash and Hadeel Abdelkhaleq for their contributions to the data analysis.

The authors received no funding for the research, authorship, or publication of this article.

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Department of Pharmacy, King Hussein Cancer Center, Amman, Jordan

Amani El Mughrabi, Sewar S. Salmany & Ala’a Dabbous

Department of Pharmacy, Ministry of Health, Amman, Jordan

Batool Aljarrat

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Conceptualization: AE and SS. Methodology: AE, SS, BA, AD and HA. Investigation and Data collection: AE, BA, AD and HA Formal analysis: AE and SS. Writing-original draft preparation: AE. Writing-Review and Editing: AE and SS. Supervision: AE and SS. All the authors read and approved the final version of the manuscript.

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Correspondence to Amani El Mughrabi .

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Mughrabi, A.E., Salmany, S.S., Aljarrat, B. et al. Appropriate use of medication among home care adult cancer patients at end of life: a retrospective observational study. BMC Palliat Care 23 , 108 (2024). https://doi.org/10.1186/s12904-024-01432-4

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Symptomatic
Avoidable medications

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Published: 22 April 2024

Molar root canal treatment performed by undergraduate dental students; an observational study of procedural errors and student perception

Ahmad M. El-Ma’aita 1 , 2 ,
Sari A. Mahasneh 1 , 2 ,
Maryam A. Hamandi 2 &
Mohammad A. Al-Rabab’ah 1 , 2

BMC Medical Education volume 24 , Article number: 437 ( 2024 ) Cite this article

219 Accesses

Metrics details

Molar root canal treatment (RCT) is challenging and requires training and specific skills. Rotary instrumentation (RI) reduces the time needed for instrumentation but may increase the risk of certain procedural errors. The aims of this study were to evaluate the quality of molar RCTs provided by undergraduate students, to compare the prevalence of procedural errors following manual and RI, and to assess the students’ self-perceived confidence to perform molar RCT without supervision and their preference for either manual or RI.

Molar RCTs performed by the final year students were evaluated radiographically according to predefined criteria (Appendix 1). The procedural errors, treatment details, and the students’ self-perceived confidence to perform molar RCT and their preference for either manual or RI were recorded. Descriptive statistics were performed, and the Chi-squared test was used to detect any statistically significant differences.

60.4% of RCTs were insufficient. RI resulted in more sufficient treatments compared with MI (49% vs. 30.3% respectively. X 2 : 7.39, p = 0.007), required fewer visits to complete (2.9 vs. 4.6 respectively. X 2 : 67.23, p < 0.001) and was the preferred technique by 93.1% of students. The most common procedural errors were underextension of the root canal obturation (48.4%), insufficient obturation (45.5%), and improper coronal seal (35.2%) without a significant difference between the two techniques. 26.4% of the participating students reported that they did not feel confident to perform molar RCT without supervision.

The quality of molar RCT provided by UG students was generally insufficient. RI partially improved the technical quality of RCT compared with MI. UG students need further endodontic training and experience before they can safely and confidently practise molar RCT.

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Root canal treatment (RCT) aims to control intra-radicular infection and prevent or treat apical periodontitis [ 1 ]. It comprises chemo-mechanical disinfection, where canals are instrumented and shaped to their full extension and disinfected using irrigants and medicaments, and then obturated in three-dimension to ensure a fluid-tight seal apically, laterally and coronally [ 2 , 3 ]. RCT is a technically demanding procedure that requires specific training and skills especially in molar teeth. Undergraduate (UG) students may lack the skills and experience necessary to carry out molar RCT. Only 13–47% of RCTs completed by UG students were of acceptable quality [ 4 , 5 , 6 , 7 , 8 ].

Procedural errors may occur during RCT even with experienced clinicians. They can manifest as errors in length control, instrumentation-related errors and insufficient obturation. The presence of such errors can jeopardize canal debridement, which may, in turn, compromise the outcome of endodontic treatment [ 9 , 10 ]. Rotary instrumentation (RI) uses motor driven nickel-titanium (NiTi) instruments that are super-elastic and demonstrate higher resistance to torsional failure compared with stainless steel instruments [ 11 , 12 ]. RI was shown to perform better than manual instrumentation (MI) when used by unexperienced clinicians and resulted in fewer procedural errors [ 13 , 14 ]. Its integration into UG dental education was suggested [ 13 ].

Research that evaluates student learning outcome should utilize competency measures as the main outcome [ 15 ]. However, students’ self-perceived confidence can influence the student’s ability to demonstrate competency and may be useful as a secondary outcome [ 16 ]. The students’ self-perceived confidence in performing endodontic procedures was the lowest for performing RCT of maxillary and mandibular molars among a list that involves a wide range of endodontic procedures [ 17 ]. Less than 40% of new dental graduates were confident to perform endodontic treatment on multirooted teeth [ 18 ].

The need for this study stems from multiple observations by our faculty supervising UG endodontic work that students struggled to perform molar RCT and that procedural errors were frequent. The aims of this observational study were (a) to assess the quality of molar RCTs provided by UG students, (b) to compare the prevalence of procedural errors associated with manual and rotary instrumentation and (c) to assess the students’ self-perceived confidence to perform molar RCT without supervision and their preference for either manual or RI.

The protocol of this study was approved by the review board committee of the Jordan University Hospital (ref 10/2022/1726). Informed consent was obtained from the participating students and their patients. All final year dental students at the University of Jordan ( n = 149) were invited to participate in this study. No exclusion criteria were implemented, and no students form other colleges were included. Molar RCTs performed by the final year dental students at the University of Jordan between October 2021– May 2022 were evaluated radiographically according to predefined criteria (Appendix 1 ). All the treated cases were of low difficulty according to the American Association of Endodontists’ case difficulty assessment form [ 19 ]. All RCTs were performed under rubber dam isolation. Working length was determined using apex locators and confirmed with a working length radiograph. Canal instrumentation was performed either manually using the step back technique, or with rotary instrumentation using the ProTaper Gold® system (Dentsply Maillefer, Baillagues, Switzerland). Obturation was carried out with gutta percha and resin sealer (AH-plus, Dentsply DeTrey, Konstanz, Germany) using cold lateral condensation. Students were supervised by faculty throughout the treatments provided. However, different supervisors were allocated to different groups of students. It was not possible to assign the same supervisors for all students due to the busy clinics schedule.

Treatment details including the number of visits used to complete the treatment, the students’ preference for either instrumentation technique, and their self-perceived confidence to perform RCT without supervision were recorded using an online questionnaire (Appendix 2 ). The questionnaire was designed was piloted on 10 students and was tested for face and content validity. The first 10 respondents were asked to complete the survey once again after one week to ensure the survey was reliable.

Post-obturation radiographs (manual type E films, Kodak, Carestream Health, Rochester, NY, USA) were assessed in a dark room using an X-ray viewer (Dentsply Rinn, Konstanz, Germany). Procedural errors that were detectable on the post-obturation peri-apical radiograph were recorded, and each completed RCT was marked as either sufficient or insufficient (Appendix 1 ). The first 10 RCTs were jointly evaluated by 3 assessors (AE, MA, and SM) following a discussion of the errors detected to ensure good calibration of the assessors. The rest of the RCTs were evaluated independently by 2 clinicians (AE and MA). In cases where there was a disagreement, the third experienced consultant endodontist (SM) was consulted. Descriptive statistics as well as the Chi-squared test were used.

A total of 109 students consented to participate. 104 students performed molar RCTs using both techniques and 5 students only performed manual instrumentation. Post-obturation radiographs of 213 RCTs were assessed (109 using MI and 104 using RI). 75.6% of treated teeth were first molars (26.8% maxillary and 48.8% mandibular) while 24.4% were second molars (10.3% maxillary and 14.1% mandibular). The overall mean number of visits required to complete the treatment was 3.7 (median: 4, standard deviation: 1.55). RI enabled the students to complete their treatment in fewer visits compared with MI (2.9 vs. 4.6 visits respectively, X 2 : 67.23, p < 0.001).

The procedural errors (as defined in Appendix 1 ) and their prevalence are summarised in Table 1 . Examples of the procedural errors are illustrated in Fig. 1 .

Procedural errors detected in the post-obturation radiographs; ( a ) under-extension of obturation in the mesio-buccal root of the maxillary right first molar, ( b ) canal transportation in the mesial root of the mandibular left first molar, ( c ) separated instrument in the mesio-lingual root of the mandibular left first molar, and ( d ) Defective coronal restoration in the mandibular right first molar

The overall technical quality of RCTs was deemed sufficient in 39.6% of the cases. There was no statistically significant difference in the quality of RCTs provided or the prevalence of procedural errors between maxillary and mandibular molars. RI resulted in more sufficient treatments compared with MI (49% vs. 30.3% respectively) (X 2 : 7.39, p = 0.007). The interrater reliability was excellent (Kappa statistic: 0.83).

Most students (93.1%) reported that they preferred RI over manual, while 6.9% of them had no preference. More than one quarter of the students (26.4%) reported that they did not feel confident to perform molar RCT without supervision.

Patients with procedural errors were informed of the unfortunate mishap and were either kept under observation, referred to a consultant endodontist or the post-graduate endodontic clinics, or, where the procedural errors were non-reparable, referred for extraction of the involved tooth.

This study demonstrated that procedural errors were very common, be it in manual or RI, and that students generally did not feel confident to perform molar RCT on their own without being supervised.

More than 60% of the treatments provided were judged to have either compromised the tooth structure, resulted in irreversible damage to the tooth or required further intervention before definitive restoration of the tooth could be completed. This is in agreement with the reported quality of RCT performed by UG students in different parts of the world [ 4 , 5 , 6 , 7 ]. RI only partially improved the quality of RCT and did not result in an acceptable level of sufficient treatments. A recent systematic review demonstrated a high tendency for procedural errors with MI [ 20 ].

The most common procedural error detected was under-extension of the root canal filling. The position of the apical constriction in relation to the radiographic apex is variable. In our study, 2 mm short of the radiographic apex was used as the cut-off point in accordance with previously published literature [ 6 , 21 , 22 ]. Under-extended root canal obturation could be explained by multiple reasons including errors in working length determination, ledge formation, lack of recapitulation during the step-back phase of instrumentation, separated instruments, improper master cone selection and improper obturation technique. The specific reason for this procedural error could not be identified in this observational study. Over-extension of the root canal filling was observed more often in MI. Lack of apical stop creation and overzealous instrumentation can be implicated for this procedural error.

Canal transportation was encountered more frequently following MI. It occurs due to the files’ inherent tendency to restore their original linear shape during canal instrumentation [ 23 ]. This is in accordance with other published studies [ 24 , 25 ].

Obturation of the instrumented canals is essential and aims to entomb any residual infection and provide a fluid-tight seal against the ingress of fluids from the peri-radicular tissues [ 3 ]. Different techniques and materials have been described but none proved to be superior to the rest. In this study, obturation was completed using cold lateral condensation. Unexperienced clinicians may find this technique difficult to apply especially in narrow canals and in patients with limited mouth openings. This was evident in our results as almost half of the obturations had voids or were poorly condensed. The sealer-based obturation technique used with calcium silicate sealers can provide a simpler obturation option as it only requires the insertion of a single cone of gutta percha with no further condensation [ 26 ]. Coronal seal is an essential part of RCT [ 27 ]. Proper adaptation of a coronal restoration to sound tooth structure prevents the ingress of saliva into the obturated root canal system, and therefore prevents reinfection. A leaky coronal restoration (definitive or provisional) not only risks reinfection of the root canal system, but also exposes the tooth to recurrent caries which may compromise its restorability [ 27 ].

This study was based on radiographic assessment of the RCTs provided. While radiographs can reveal important mechanical aspects of RCT such as the extension, taper, and condensation of the root filling as well as the adaptation of the coronal restoration, they do not allow the assessment of the biological part of treatment [ 28 ]. Isolation during treatment, the irrigation protocol (solution(s), volume, time, activation… etc.), interappointment medication and quality and timing of coronal restoration are all factors that may influence the treatment outcome yet cannot be assessed radiographically. However, to achieve the best possible outcome, the mechanical steps of RCT should be executed to a very high standard and procedural errors should be avoided as much as possible. Poor technical quality of RCT was demonstrated to be a risk factor for apical periodontitis [ 9 , 29 ].

The European society of endodontology’s undergraduate curriculum guidelines for endodontology recommend that “all students should gain adequate experience in the treatment of anterior, premolar and molar teeth in both the pre-clinical and clinical environment” [ 30 ]. They also state that clinical training should be based on competencies rather than a minimum number of performed procedures. Students should be trained to consider all treatment options, be competent at assessing tooth restorability and treatment complexity and to recognize when referral to a specialist should be considered [ 30 ].

This study has multiple limitations. It only evaluated the radiographic quality of molar RCTs. No clinical aspect was taken into consideration. Its lack of temporal factor precluded any observation of the success or failure of treatments and their association (or lack of) with the technical quality of the treatments provided. Clinical supervision varied between the participating students and there was no correlation between the students’ academic performance and the technical quality of RCTs. Potential confounding factors to the results include the level of academic performance of students, the variance in clinical supervision, the technical difficulty of the RCT provided, and the variation in outcome assessment between the assessors. No attempts to adjust for the confounding factors were made as the purpose of the study was to report on the prevalence of procedural errors rather than investigating the potential reasons for them. However, this study demonstrates an overall poor quality of molar RCT provided by UG students, combined with their lack of confidence to perform this procedure without supervision. This invites the question of whether UG students should be expected to perform molar RCT at such an early stage of their careers, or whether this procedure requires further training, mentorship and experience that may not be ideally delivered during undergraduate training. Inexperienced clinicians may benefit from a wider exposure to simple RCTs of anterior and premolar teeth before they can embark on the more technically demanding molar RCT. The authors suggest that UG endodontic clinical training should emphasize on providing simple RCTs on anterior and premolar teeth and on the conservative and emergency management of molar teeth such as vital pulp therapy, access cavity and coronal pulp extirpation, and incision and drainage. Clinicians who wish to perform molar RCT should receive further training following graduating from the dental school.

The technical quality of molar RCT provided by UG students is generally insufficient. RI partially improved the quality of RCT compared with MI when used by inexperienced operators (UG students). Most students preferred RI over MI. UG students need further endodontic training and experience before they can safely and confidently practise molar RCT.

Data availability

The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.

Abbreviations

manual instrumentation

root canal treatment

rotary instrumentation

undergraduate

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El-Ma’aita, A.M., Mahasneh, S.A., Hamandi, M.A. et al. Molar root canal treatment performed by undergraduate dental students; an observational study of procedural errors and student perception. BMC Med Educ 24 , 437 (2024). https://doi.org/10.1186/s12909-024-05397-z

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Reproductive rights in America

What's at stake as the supreme court hears idaho case about abortion in emergencies.

Selena Simmons-Duffin

The Supreme Court will hear another case about abortion rights on Wednesday. Protestors gathered outside the court last month when the case before the justices involved abortion pills. Tom Brenner for The Washington Post/Getty Images hide caption

The Supreme Court will hear another case about abortion rights on Wednesday. Protestors gathered outside the court last month when the case before the justices involved abortion pills.

In Idaho, when a pregnant patient has complications, abortion is only legal to prevent the woman's death. But a federal law known as EMTALA requires doctors to provide "stabilizing treatment" to patients in the emergency department.

The Biden administration sees that as a direct conflict, which is why the abortion issue is back – yet again – before the Supreme Court on Wednesday.

The case began just a few weeks after the justices overturned Roe v. Wade in 2022, when the federal Justice Department sued Idaho , arguing that the court should declare that "Idaho's law is invalid" when it comes to emergency abortions because the federal emergency care law preempts the state's abortion ban. So far, a district court agreed with the Biden administration, an appeals court panel agreed with Idaho, and the Supreme Court allowed the strict ban to take effect in January when it agreed to hear the case.

Supreme Court allows Idaho abortion ban to be enacted, first such ruling since Dobbs

The case, known as Moyle v. United States (Mike Moyle is the speaker of the Idaho House), has major implications on everything from what emergency care is available in states with abortion bans to how hospitals operate in Idaho. Here's a summary of what's at stake.

1. Idaho physicians warn patients are being harmed

Under Idaho's abortion law , the medical exception only applies when a doctor judges that "the abortion was necessary to prevent the death of the pregnant woman." (There is also an exception to the Idaho abortion ban in cases of rape or incest, only in the first trimester of the pregnancy, if the person files a police report.)

In a filing with the court , a group of 678 physicians in Idaho described cases in which women facing serious pregnancy complications were either sent home from the hospital or had to be transferred out of state for care. "It's been just a few months now that Idaho's law has been in effect – six patients with medical emergencies have already been transferred out of state for [pregnancy] termination," Dr. Jim Souza, chief physician executive of St. Luke's Health System in Idaho, told reporters on a press call last week.

Those delays and transfers can have consequences. For example, Dr. Emily Corrigan described a patient in court filings whose water broke too early, which put her at risk of infection. After two weeks of being dismissed while trying to get care, the patient went to Corrigan's hospital – by that time, she showed signs of infection and had lost so much blood she needed a transfusion. Corrigan added that without receiving an abortion, the patient could have needed a limb amputation or a hysterectomy – in other words, even if she didn't die, she could have faced life-long consequences to her health.

Attorneys for Idaho defend its abortion law, arguing that "every circumstance described by the administration's declarations involved life-threatening circumstances under which Idaho law would allow an abortion."

Ryan Bangert, senior attorney for the Christian legal powerhouse Alliance Defending Freedom, which is providing pro-bono assistance to the state of Idaho, says that "Idaho law does allow for physicians to make those difficult decisions when it's necessary to perform an abortion to save the life of the mother," without waiting for patients to become sicker and sicker.

Still, Dr. Sara Thomson, an OB-GYN in Boise, says difficult calls in the hospital are not hypothetical or even rare. "In my group, we're seeing this happen about every month or every other month where this state law complicates our care," she says. Four patients have sued the state in a separate case arguing that the narrow medical exception harmed them.

"As far as we know, we haven't had a woman die as a consequence of this law, but that is really on the top of our worry list of things that could happen because we know that if we watch as death is approaching and we don't intervene quickly enough, when we decide finally that we're going to intervene to save her life, it may be too late," she says.

2. Hospitals are closing units and struggling to recruit doctors

Labor and delivery departments are expensive for hospitals to operate. Idaho already had a shortage of providers, including OB-GYNS. Hospital administrators now say the Idaho abortion law has led to an exodus of maternal care providers from the state, which has a population of 2 million people.

Three rural hospitals in Idaho have closed their labor-and-delivery units since the abortion law took effect. "We are seeing the expansion of what's called obstetrical deserts here in Idaho," said Brian Whitlock, president and CEO of the Idaho Hospital Association.

Since Idaho's abortion law took effect, nearly one in four OB-GYNs have left the state or retired, according to a report from the Idaho Physician Well-Being Action Collaborative. The report finds the loss of doctors who specialize in high-risk pregnancies is even more extreme – five of nine full time maternal-fetal medicine specialists have left Idaho.

Administrators say they aren't able to recruit new providers to fill those positions. "Since [the abortion law's] enactment, St. Luke's has had markedly fewer applicants for open physician positions, particularly in obstetrics. And several out-of-state candidates have withdrawn their applications upon learning of the challenges of practicing in Idaho, citing [the law's] enactment and fear of criminal penalties," reads an amicus brief from St. Luke's health system in support of the federal government.

"Prior to the abortion decision, we already ranked 50th in number of physicians per capita – we were already a strained state," says Thomson, the doctor in Boise. She's experienced the loss of OB-GYN colleagues first hand. "I had a partner retire right as the laws were changing and her position has remained open – unfilled now for almost two years – so my own personal group has been short-staffed," she says.

ADF's Bangert says he's skeptical of the assertion that the abortion law is responsible for this exodus of doctors from Idaho. "I would be very surprised if Idaho's abortion law is the sole or singular cause of any physician shortage," he says. "I'm very suspicious of any claims of causality."

3. Justices could weigh in on fetal "personhood"

The state of Idaho's brief argues that EMTALA actually requires hospitals "to protect and care for an 'unborn child,'" an argument echoed in friend-of-the-court briefs from the U.S. Conference of Catholic Bishops and a group of states from Indiana to Wyoming that also have restrictive abortion laws. They argue that abortion can't be seen as a stabilizing treatment if one patient dies as a result.

Thomson is also Catholic, and she says the idea that, in an emergency, she is treating two patients – the fetus and the mother – doesn't account for clinical reality. "Of course, as obstetricians we have a passion for caring for both the mother and the baby, but there are clinical situations where the mom's health or life is in jeopardy, and no matter what we do, the baby is going to be lost," she says.

The Idaho abortion law uses the term "unborn child" as opposed to the words "embryo" or "fetus" – language that implies the fetus has the same rights as other people.

Shots - Health News

The science of ivf: what to know about alabama's 'extrauterine children' ruling.

Mary Ziegler , a legal historian at University of California - Davis, who is writing a book on fetal personhood, describes it as the "North Star" of the anti-abortion rights movement. She says this case will be the first time the Supreme Court justices will be considering a statute that uses that language.

"I think we may get clues about the future of bigger conflicts about fetal personhood," she explains, depending on how the justices respond to this idea. "Not just in the context of this statute or emergency medical scenarios, but in the context of the Constitution."

ADF has dismissed the idea that this case is an attempt to expand fetal rights. "This case is, at root, a question about whether or not the federal government can affect a hostile takeover of the practice of medicine in all 50 states by misinterpreting a long-standing federal statute to contain a hidden nationwide abortion mandate," Bangert says.

4. The election looms large

Ziegler suspects the justices will allow Idaho's abortion law to remain as is. "The Supreme Court has let Idaho's law go into effect, which suggests that the court is not convinced by the Biden administration's arguments, at least at this point," she notes.

Trump backed a federal abortion ban as president. Now, he says he wouldn't sign one

Whatever the decision, it will put abortion squarely back in the national spotlight a few months before the November election. "It's a reminder on the political side of things, that Biden and Trump don't really control the terms of the debate on this very important issue," Zielger observes. "They're going to be things put on everybody's radar by other actors, including the Supreme Court."

The justices will hear arguments in the case on Wednesday morning. A decision is expected by late June or early July.

Correction April 23, 2024

An earlier version of this story did not mention the rape and incest exception to Idaho's abortion ban. A person who reports rape or incest to police can end a pregnancy in Idaho in the first trimester.

Abortion rights
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Chronic wasting disease: Death of 2 hunters in US raises concerns of 'zombie deer'

The 2022 report of two hunters who developed neurological diseases after eating potentially infected deer meat has raised concerns 'zombie deer disease' could pass to humans as mad cow disease did..

Two hunters who ate meat from a population of deer known to have chronic wasting disease − or "zombie deer disease" − developed similar neurological conditions and died, raising concerns that it can pass from animals to humans.

Found in deer in northern Colorado and southern Wyoming in the 1990s, chronic wasting disease (CWD) has been recorded in free-ranging deer, elk and moose in at least 32 states across all parts of the continental U.S., according to the U.S. Centers for Disease Control and Prevention .

Deer infected with CWD may be called "zombie deer" because the disease leads to weight loss, lack of coordination, stumbling, listlessness, weight loss, drooling, and lack of fear of people.

The 2022 case did prove that CWD could infect humans. But scientists and health officials have been concerned that CWD could jump to humans as mad cow disease did in the United Kingdom in the 1990s . In 2022, scientists in Canada published a study, based on mice research, suggesting a risk of CWD transmission to humans .

Here's what you need to know about chronic wasting disease and whether you need to worry about it.

Researchers identify troubling case involving 2 deaths

Researchers at the University of Texas Health Science Center at San Antonio have reported how two hunters who ate venison from a deer population known to have CWD died in 2022 after developing sporadic Creutzfeldt-Jakob disease (CJD), which is a neurological disease like CWD.

The second man to die, who was 77, suffered "rapid-onset confusion and aggression," the researchers said, and died within a month despite treatment.

"The patient’s history, including a similar case in his social group, suggests a possible novel animal-to-human transmission of CWD," they wrote in the case report , which was presented earlier this month at the annual meeting of the American Academy of Neurology and published in the peer-reviewed journal Neurology.

The researchers did not say where the men lived or hunted. But the highest concentration of CWD-infected deer can be found in Kansas, Nebraska, Wisconsin and Wyoming, according to CDC and US. Geological Survey reports.

Because of the difficulty in distinguishing between the diseases, the researchers said the case does not represent a proven case of transmission. However, "this cluster emphasizes the need for further investigation into the potential risks of consuming CWD-infected deer and its implications for public health," they wrote.

'Zombie deer disease': What to know about chronic wasting disease and its spread in the US.

What is 'zombie deer disease'? What are prion diseases?

Also known as chronic wasting disease, "zombie deer disease" is a prion disease, a rare, progressive and fatal neurodegenerative disorder that affects deer, elk, moose and other animals, the CDC says.

In prion diseases, the abnormal folding of certain "prion proteins" leads to brain damage and other symptoms, according to the CDC. Prion diseases , which usually progress rapidly and are always fatal, can affect humans and animals.

Creutzfeldt-Jacob disease (CJD) and variant Creutzfeldt-Jacob disease (vCJD), which is a form of mad cow disease, are prion diseases found in people.

Mad cow disease is an example of a prion disease that can spread from cattle to humans, and some researchers have likened "zombie deer disease" to it.

For instance, with mad cow disease, it usually took four to six years from infection for cattle to show symptoms, according to the Food and Drug Administration . Deer may have an incubation period of up to two years before the onset of symptoms. So, the animals could have the disease but look normal until the onset of symptoms, such as weight loss, notes the U.S. Geological Survey .

The development of vCJD in humans in the wake of mad cow disease – its official name is bovine spongiform encephalopathy, or BSE – through eating meat from contaminated cattle has concerned scientists about the possible transmission of chronic wasting disease (CWD) to humans.

Can 'zombie deer disease' be transmitted to humans?

Even though there has been no known confirmed case of deer-to-human transmission of "zombie deer disease,' concerns have risen since officials found CWD in a dead deer in Yellowstone National Park in November.

"As of yet, there has been no transmission from deer or elk to humans," Jennifer Mullinax, associate professor of wildlife ecology and management at the University of Maryland, told BBC . "However, given the nature of prions, CDC and other agencies have supported all efforts to keep any prion disease out of the food chain."

Should CWD transmit to humans, it could create a "potential crisis" similar to what mad cow disease caused, Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota, told BBC .

"However, it’s important to note that BSE and CWD prions differ structurally, and we do not yet know whether the pathology and clinical presentation would be comparable if CWD transmission to humans were to occur," he said.

Meanwhile, chronic wasting disease continues to spread to more states; the most recent is Indiana. The disease was detected this month in a male white-tailed deer in the northeastern part of the state, which borders part of Michigan, where CWD had been detected earlier, according to the Center for Infectious Disease Research and Policy .

The U.S. Geological Survey updated its tracking of chronic wasting disease on Friday to include 33 states (adding Indiana), as well as four Canadian provinces and four other countries (Finland, Norway, Sweden and South Korea).

Contributing: Sara Chernikoff and Julia Gomez

Follow Mike Snider on X and Threads: @mikesnider & mikegsnider .

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Biochem Med (Zagreb)
v.24(2); 2014 Jun

Observational and interventional study design types; an overview

The appropriate choice in study design is essential for the successful execution of biomedical and public health research. There are many study designs to choose from within two broad categories of observational and interventional studies. Each design has its own strengths and weaknesses, and the need to understand these limitations is necessary to arrive at correct study conclusions.

Observational study designs, also called epidemiologic study designs, are often retrospective and are used to assess potential causation in exposure-outcome relationships and therefore influence preventive methods. Observational study designs include ecological designs, cross sectional, case-control, case-crossover, retrospective and prospective cohorts. An important subset of observational studies is diagnostic study designs, which evaluate the accuracy of diagnostic procedures and tests as compared to other diagnostic measures. These include diagnostic accuracy designs, diagnostic cohort designs, and diagnostic randomized controlled trials.

Interventional studies are often prospective and are specifically tailored to evaluate direct impacts of treatment or preventive measures on disease. Each study design has specific outcome measures that rely on the type and quality of data utilized. Additionally, each study design has potential limitations that are more severe and need to be addressed in the design phase of the study. This manuscript is meant to provide an overview of study design types, strengths and weaknesses of common observational and interventional study designs.

Introduction

Study design plays an important role in the quality, execution, and interpretation of biomedical and public health research ( 1 – 12 ). Each study design has their own inherent strengths and weaknesses, and there can be a general hierarchy in study designs, however, any hierarchy cannot be applied uniformly across study design types ( 3 , 5 , 6 , 9 ). Epidemiological and interventional research studies include three elements; 1) definition and measure of exposure in two or more groups, 2) measure of health outcome(s) in these same groups, and 3) statistical comparison made between groups to assess potential relationships between the exposure and outcome, all of which are defined by the researcher ( 1 – 4 , 8 , 13 ). The measure of exposure in epidemiologic studies may be tobacco use (“Yes” vs . “No”) to define the two groups and may be the treatment (Active drug vs . placebo) in interventional studies. Health outcome(s) can be the development of a disease or symptom (e.g. lung cancer) or curing a disease or symptom (e.g. reduction of pain). Descriptive studies, which are not epidemiological or interventional, lack one or more of these elements and have limited application. High quality epidemiological and interventional studies contain detailed information on the design, execution and interpretation of results, with methodology clearly written and able to be reproduced by other researchers.

Research is generally considered as primary or secondary research. Primary research relies upon data gathered from original research expressly for that purpose ( 1 , 3 , 5 ). Secondary research focuses on single or multiple data sources that are not collected for a single research purpose ( 14 , 15 ). Secondary research includes meta-analyses and best practice guidelines for treatments. This paper will focus on the study designs and their strengths, weaknesses, and common statistical outcomes of primary research.

The choice of a study design hinges on many factors, including prior research, availability of study participants, funding, and time constraints. One common decision point is the desire to suggest causation. The most common causation criteria are proposed by Hill ( 16 ). Of these, demonstrating temporality is the only mandatory criterion for suggesting temporality. Therefore, prospective studies that follow study participants forward through time, including prospective cohort studies and interventional studies, are best suited for suggesting causation. Causal conclusions cannot be proven from an observational study. Additionally, causation between an exposure and an outcome cannot be proven by one study alone; multiple studies across different populations should be considered when making causation assessments ( 17 ).

Primary research has been categorized in different ways. Common categorization schema include temporal nature of the study design (retrospective or prospective), usability of the study results (basic or applied), investigative purpose (descriptive or analytical), purpose (prevention, diagnosis or treatment), or role of the investigator (observational or interventional). This manuscript categorizes study designs by observational and interventional criteria, however, other categorization methods are described as well.

Observational and interventional studies

Within primary research there are observational studies and interventional studies. Observational studies, also called epidemiological studies, are those where the investigator is not acting upon study participants, but instead observing natural relationships between factors and outcomes. Diagnostic studies are classified as observational studies, but are a unique category and will be discussed independently. Interventional studies, also called experimental studies, are those where the researcher intercedes as part of the study design. Additionally, study designs may be classified by the role that time plays in the data collection, either retrospective or prospective. Retrospective studies are those where data are collected from the past, either through records created at that time or by asking participants to remember their exposures or outcomes. Retrospective studies cannot demonstrate temporality as easily and are more prone to different biases, particularly recall bias. Prospective studies follow participants forward through time, collecting data in the process. Prospective studies are less prone to some types of bias and can more easily demonstrate that the exposure preceded the disease, thereby more strongly suggesting causation. Table 1 describes the broad categories of observational studies: the disease measures applicable to each, the appropriate measures of risk, and temporality of each study design. Epidemiologic measures include point prevalence, the proportion of participants with disease at a given point in time, period prevalence, the proportion of participants with disease within a specified time frame, and incidence, the accumulation of new cases over time. Measures of risk are generally categorized into two categories: those that only demonstrate an association, such as an odds ratio (and some other measures), and those that demonstrate temporality and therefore suggest causation, such as hazard ratio. Table 2 outlines the strengths and weaknesses of each observational study design.

Observational study design measures of disease, measures of risk, and temporality.

Observational study design strengths and weaknesses.

Observational studies

Ecological study design.

The most basic observational study is an ecological study. This study design compares clusters of people, usually grouped based on their geographical location or temporal associations ( 1 , 2 , 6 , 9 ). Ecological studies assign one exposure level for each distinct group and can provide a rough estimation of prevalence of disease within a population. Ecological studies are generally retrospective. An example of an ecological study is the comparison of the prevalence of obesity in the United States and France. The geographic area is considered the exposure and the outcome is obesity. There are inherent potential weaknesses with this approach, including loss of data resolution and potential misclassification ( 10 , 11 , 13 , 18 , 19 ). This type of study design also has additional weaknesses. Typically these studies derive their data from large databases that are created for purposes other than research, which may introduce error or misclassification ( 10 , 11 ). Quantification of both the number of cases and the total population can be difficult, leading to error or bias. Lastly, due to the limited amount of data available, it is difficult to control for other factors that may mask or falsely suggest a relationship between the exposure and the outcome. However, ecological studies are generally very cost effective and are a starting point for hypothesis generation.

Proportional mortality ratio study design

Proportional mortality ratio studies (PMR) utilize the defined well recorded outcome of death and subsequent records that are maintained regarding the decedent ( 1 , 6 , 8 , 20 ). By using records, this study design is able to identify potential relationships between exposures, such as geographic location, occupation, or age and cause of death. The epidemiological outcomes of this study design are proportional mortality ratio and standardized mortality ratio. In general these are the ratio of the proportion of cause-specific deaths out of all deaths between exposure categories ( 20 ). As an example, these studies can address questions about higher proportion of cardiovascular deaths among different ethnic and racial groups ( 21 ). A significant drawback to the PMR study design is that these studies are limited to death as an outcome ( 3 , 5 , 22 ). Additionally, the reliance on death records makes it difficult to control for individual confounding factors, variables that either conceal or falsely demonstrate associations between the exposure and outcome. An example of a confounder is tobacco use confounding the relationship between coffee intake and cardiovascular disease. Historically people often smoked and drank coffee while on coffee breaks. If researchers ignore smoking they would inaccurately find a strong relationship between coffee use and cardiovascular disease, where some of the risk is actually due to smoking. There are also concerns regarding the accuracy of death certificate data. Strengths of the study design include the well-defined outcome of death, the relative ease and low cost of obtaining data, and the uniformity of collection of these data across different geographical areas.

Cross-sectional study design

Cross-sectional studies are also called prevalence studies because one of the main measures available is study population prevalence ( 1 – 12 ). These studies consist of assessing a population, as represented by the study sample, at a single point in time. A common cross-sectional study type is the diagnostic accuracy study, which is discussed later. Cross-sectional study samples are selected based on their exposure status, without regard for their outcome status. Outcome status is obtained after participants are enrolled. Ideally, a wider distribution of exposure will allow for a higher likelihood of finding an association between the exposure and outcome if one exists ( 1 – 3 , 5 , 8 ). Cross-sectional studies are retrospective in nature. An example of a cross-sectional study would be enrolling participants who are either current smokers or never smokers, and assessing whether or not they have respiratory deficiencies. Random sampling of the population being assessed is more important in cross-sectional studies as compared to other observational study designs. Selection bias from non-random sampling may result in flawed measure of prevalence and calculation of risk. The study sample is assessed for both exposure and outcome at a single point in time. Because both exposure and outcome are assessed at the same time, temporality cannot be demonstrated, i.e. it cannot be demonstrated that the exposure preceded the disease ( 1 – 3 , 5 , 8 ). Point prevalence and period prevalence can be calculated in cross-sectional studies. Measures of risk for the exposure-outcome relationship that can be calculated in cross-sectional study design are odds ratio, prevalence odds ratio, prevalence ratio, and prevalence difference. Cross-sectional studies are relatively inexpensive and have data collected on an individual which allows for more complete control for confounding. Additionally, cross-sectional studies allow for multiple outcomes to be assessed simultaneously.

Case-control study design

Case-control studies were traditionally referred to as retrospective studies, due to the nature of the study design and execution ( 1 – 12 , 23 , 24 ). In this study design, researchers identify study participants based on their case status, i.e. diseased or not diseased. Quantification of the number of individuals among the cases and the controls who are exposed allow for statistical associations between exposure and outcomes to be established ( 1 – 3 , 5 , 8 ). An example of a case control study is analysing the relationship between obesity and knee replacement surgery. Cases are participants who have had knee surgery, and controls are a random sampling of those who have not, and the comparison is the relative odds of being obese if you have knee surgery as compared to those that do not. Matching on one or more potential confounders allows for minimization of those factors as potential confounders in the exposure-outcome relationship ( 1 – 3 , 5 , 8 ). Additionally, case-control studies are at increased risk for bias, particularly recall bias, due to the known case status of study participants ( 1 – 3 , 5 , 8 ). Other points of consideration that have specific weight in case-control studies include the appropriate selection of controls that balance generalizability and minimize bias, the minimization of survivor bias, and the potential for length time bias ( 25 ). The largest strength of case-control studies is that this study design is the most efficient study design for rare diseases. Additional strengths include low cost, relatively fast execution compared to cohort studies, the ability to collect individual participant specific data, the ability to control for multiple confounders, and the ability to assess multiple exposures of interest. The measure of risk that is calculated in case-control studies is the odds ratio, which are the odds of having the exposure if you have the disease. Other measures of risk are not applicable to case-control studies. Any measure of prevalence and associated measures, such as prevalence odds ratio, in a case-control study is artificial because the researcher arbitrarily sets the proportion of cases to non-cases in this study design. Temporality can be suggested, however, it is rarely definitively demonstrated because it is unknown if the development of the disease truly preceded the exposure. It should be noted that for certain outcomes, particularly death, the criteria for demonstrating temporality in that specific exposure-outcome relationship are met and the use of relative risk as a measure of risk may be justified.

Case-crossover study design

A case-crossover study relies upon an individual to act as their own control for comparison issues, thereby minimizing some potential confounders ( 1 , 5 , 12 ). This study design should not be confused with a crossover study design which is an interventional study type and is described below. For case-crossover studies, cases are assessed for their exposure status immediately prior to the time they became a case, and then compared to their own exposure at a prior point where they didn’t become a case. The selection of the prior point for comparison issues is often chosen at random or relies upon a mean measure of exposure over time. Case-crossover studies are always retrospective. An example of a case-crossover study would be evaluating the exposure of talking on a cell phone and being involved in an automobile crash. Cases are drivers involved in a crash and the comparison is that same driver at a random timeframe where they were not involved in a crash. These types of studies are particularly good for exposure-outcome relationships where the outcome is acute and well defined, e.g. electrocutions, lacerations, automobile crashes, etc. ( 1 , 5 ). Exposure-outcome relationships that are assessed using case-crossover designs should have health outcomes that do not have a subclinical or undiagnosed period prior to becoming a “case” in the study ( 12 ). The exposure is cell phone use during the exposure periods, both before the crash and during the control period. Additionally, the reliance upon prior exposure time requires that the exposure not have an additive or cumulative effect over time ( 1 , 5 ). Case-crossover study designs are at higher risk for having recall bias as compared with other study designs ( 12 ). Study participants are more likely to remember an exposure prior to becoming a case, as compared to not becoming a case.

Retrospective and prospective cohort study design

Cohort studies involve identifying study participants based on their exposure status and either following them through time to identify which participants develop the outcome(s) of interest, or look back at data that were created in the past, prior to the development of the outcome. Prospective cohort studies are considered the gold standard of observational research ( 1 – 3 , 5 , 8 , 10 , 11 ). These studies begin with a cross-sectional study to categorize exposure and identify cases at baseline. Disease-free participants are then followed and cases are measured as they develop. Retrospective cohort studies also begin with a cross-sectional study to categorize exposure and identify cases. Exposures are then measured based on records created at that time. Additionally, in an ideal retrospective cohort, case status is also tracked using historical data that were created at that point in time. Occupational groups, particularly those that have regular surveillance or certifications such as Commercial Truck Drivers, are particularly well positioned for retrospective cohort studies because records of both exposure and outcome are created as part of commercial and regulatory purposes ( 8 ). These types of studies have the ability to demonstrate temporality and therefore identify true risk factors, not associated factors, as can be done in other types of studies.

Cohort studies are the only observational study that can calculate incidence, both cumulative incidence and an incidence rate ( 1 , 3 , 5 , 6 , 10 , 11 ). Also, because the inception of a cohort study is identical to a cross-sectional study, both point prevalence and period prevalence can be calculated. There are many measures of risk that can be calculated from cohort study data. Again, the measures of risk for the exposure-outcome relationship that can be calculated in cross-sectional study design of odds ratio, prevalence odds ratio, prevalence ratio, and prevalence difference can be calculated in cohort studies as well. Measures of risk that leverage a cohort study’s ability to calculate incidence include incidence rate ratio, relative risk, risk ratio, and hazard ratio. These measures that demonstrate temporality are considered stronger measures for demonstrating causation and identification of risk factors.

Diagnostic testing and evaluation study designs

A specific study design is the diagnostic accuracy study, which is often used as part of the clinical decision making process. Diagnostic accuracy study designs are those that compare a new diagnostic method with the current “gold standard” diagnostic procedure in a cross-section of both diseased and healthy study participants. Gold standard diagnostic procedures are the current best-practice for diagnosing a disease. An example is comparing a new rapid test for a cancer with the gold standard method of biopsy. There are many intricacies to diagnostic testing study designs that should be considered. The proper selection of the gold standard evaluation is important for defining the true measures of accuracy for the new diagnostic procedure. Evaluations of diagnostic test results should be blinded to the case status of the participant. Similar to the intention-to-treat concept discussed later in interventional studies, diagnostic tests have a procedure of analyses called intention to diagnose (ITD), where participants are analysed in the diagnostic category they were assigned, regardless of the process in which a diagnosis was obtained. Performing analyses according to an a priori defined protocol, called per protocol analyses (PP or PPA), is another potential strength to diagnostic study testing. Many measures of the new diagnostic procedure, including accuracy, sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio can be calculated. These measures of the diagnostic test allow for comparison with other diagnostic tests and aid the clinician in determining which test to utilize.

Interventional study designs

Interventional study designs, also called experimental study designs, are those where the researcher intervenes at some point throughout the study. The most common and strongest interventional study design is a randomized controlled trial, however, there are other interventional study designs, including pre-post study design, non-randomized controlled trials, and quasi-experiments ( 1 , 5 , 13 ). Experimental studies are used to evaluate study questions related to either therapeutic agents or prevention. Therapeutic agents can include prophylactic agents, treatments, surgical approaches, or diagnostic tests. Prevention can include changes to protective equipment, engineering controls, management, policy or any element that should be evaluated as to a potential cause of disease or injury.

Pre-post study design

A pre-post study measures the occurrence of an outcome before and again after a particular intervention is implemented. A good example is comparing deaths from motor vehicle crashes before and after the enforcement of a seat-belt law. Pre-post studies may be single arm, one group measured before the intervention and again after the intervention, or multiple arms, where there is a comparison between groups. Often there is an arm where there is no intervention. The no-intervention arm acts as the control group in a multi-arm pre-post study. These studies have the strength of temporality to be able to suggest that the outcome is impacted by the intervention, however, pre-post studies do not have control over other elements that are also changing at the same time as the intervention is implemented. Therefore, changes in disease occurrence during the study period cannot be fully attributed to the specific intervention. Outcomes measured for pre-post intervention studies may be binary health outcomes such as incidence or prevalence, or mean values of a continuous outcome such as systolic blood pressure may also be used. The analytic methods of pre-post studies depend on the outcome being measured. If there are multiple treatment arms, it is also likely that the difference from beginning to end within each treatment arm are analysed.

Non-randomized trial study design

Non-randomized trials are interventional study designs that compare a group where an intervention was performed with a group where there was no intervention. These are convenient study designs that are most often performed prospectively and can suggest possible relationships between the intervention and the outcome. However, these study designs are often subject to many types of bias and error and are not considered a strong study design.

Randomized controlled trial study design

Randomized controlled trials (RCTs) are the most common type of interventional study, and can have many modifications ( 26 – 28 ). These trials take a homogenous group of study participants and randomly divide them into two separate groups. If the randomization is successful then these two groups should be the same in all respects, both measured confounders and unmeasured factors. The intervention is then implemented in one group and not the other and comparisons of intervention efficacy between the two groups are analysed. Theoretically, the only difference between the two groups through the entire study is the intervention. An excellent example is the intervention of a new medication to treat a specific disease among a group of patients. This randomization process is arguably the largest strength of an RCT ( 26 – 28 ). Additional methodological elements are utilized among RCTs to further strengthen the causal implication of the intervention’s impact. These include allocation concealment, blinding, measuring compliance, controlling for co-interventions, measuring dropout, analysing results by intention to treat, and assessing each treatment arm at the same time point in the same manner.

Crossover randomized controlled trial study design

A crossover RCT is a type of interventional study design where study participants intentionally “crossover” to the other treatment arm. This should not be confused with the observational case-crossover design. A crossover RCT begins the same as a traditional RCT, however, after the end of the first treatment phase, each participant is re-allocated to the other treatment arm. There is often a wash-out period in between treatment periods. This design has many strengths, including demonstrating reversibility, compensating for unsuccessful randomization, and improving study efficiency by not using time to recruit subjects.

Allocation concealment theoretically guarantees that the implementation of the randomization is free from bias. This is done by ensuring that the randomization scheme is concealed from all individuals involved ( 26 – 30 ). A third party who is not involved in the treatment or assessment of the trial creates the randomization schema and study participants are randomized according to that schema. By concealing the schema, there is a minimization of potential deviation from that randomization, either consciously or otherwise by the participant, researcher, provider, or assessor. The traditional method of allocation concealment relies upon sequentially numbered opaque envelopes with the treatment allocation inside. These envelopes are generated before the study begins using the selected randomization scheme. Participants are then allocated to the specific intervention arm in the pre-determined order dictated by the schema. If allocation concealment is not utilized, there is the possibility of selective enrolment into an intervention arm, potentially with the outcome of biased results.

Blinding in an RCT is withholding the treatment arm from individuals involved in the study. This can be done through use of placebo pills, deactivated treatment modalities, or sham therapy. Sham therapy is a comparison procedure or treatment which is identical to the investigational intervention except it omits a key therapeutic element, thus rendering the treatment ineffective. An example is a sham cortisone injection, where saline solution of the same volume is injected instead of cortisone. This helps ensure that patients do not know if they are receiving the active or control treatment. The process of blinding is utilized to help ensure equal treatment of the different groups, therefore continuing to isolate the difference in outcome between groups to only the intervention being administered ( 28 – 31 ). Blinding within an RCT includes patient blinding, provider blinding, or assessor blinding. In some situations it is difficult or impossible to blind one or more of the parties involved, but an ideal study would have all parties blinded until the end of the study ( 26 – 28 , 31 , 32 ).

Compliance is the degree of how well study participants adhere to the prescribed intervention. Compliance or non-compliance to the intervention can have a significant impact on the results of the study ( 26 – 29 ). If there is a differentiation in the compliance between intervention arms, that differential can mask true differences, or erroneously conclude that there are differences between the groups when one does not exist. The measurement of compliance in studies addresses the potential for differences observed in intervention arms due to intervention adherence, and can allow for partial control of differences either through post hoc stratification or statistical adjustment.

Co-interventions, interventions that impact the outcome other than the primary intervention of the study, can also allow for erroneous conclusions in clinical trials ( 26 – 28 ). If there are differences between treatment arms in the amount or type of additional therapeutic elements then the study conclusions may be incorrect ( 29 ). For example, if a placebo treatment arm utilizes more over-the-counter medication than the experimental treatment arm, both treatment arms may have the same therapeutic improvement and show no effect of the experimental treatment. However, the placebo arm improvement is due to the over-the-counter medication and if that was prohibited, there may be a therapeutic difference between the two treatment arms. The exclusion or tracking and statistical adjustment of co-interventions serves to strengthen an RCT by minimizing this potential effect.

Participants drop out of a study for multiple reasons, but if there are differential dropout rates between intervention arms or high overall dropout rates, there may be biased data or erroneous study conclusions ( 26 – 28 ). A commonly accepted dropout rate is 20% however, studies with dropout rates below 20% may have erroneous conclusions ( 29 ). Common methods for minimizing dropout include incentivizing study participation or short study duration, however, these may also lead to lack of generalizability or validity.

Intention-to-treat (ITT) analysis is a method of analysis that quantitatively addresses deviations from random allocation ( 26 – 28 ). This method analyses individuals based on their allocated intervention, regardless of whether or not that intervention was actually received due to protocol deviations, compliance concerns or subsequent withdrawal. By maintaining individuals in their allocated intervention for analyses, the benefits of randomization will be captured ( 18 , 26 – 29 ). If analysis of actual treatment is solely relied upon, then some of the theoretical benefits of randomization may be lost. This analysis method relies on complete data. There are different approaches regarding the handling of missing data and no consensus has been put forth in the literature. Common approaches are imputation or carrying forward the last observed data from individuals to address issues of missing data ( 18 , 19 ).

Assessment timing can play an important role in the impact of interventions, particularly if intervention effects are acute and short lived ( 26 – 29 , 33 ). The specific timing of assessments are unique to each intervention, however, studies that allow for meaningfully different timing of assessments are subject to erroneous results. For example, if assessments occur differentially after an injection of a particularly fast acting, short-lived medication the difference observed between intervention arms may be due to a higher proportion of participants in one intervention arm being assessed hours after the intervention instead of minutes. By tracking differences in assessment times, researchers can address the potential scope of this problem, and try to address it using statistical or other methods ( 26 – 28 , 33 ).

Randomized controlled trials are the principle method for improving treatment of disease, and there are some standardized methods for grading RCTs, and subsequently creating best practice guidelines ( 29 , 34 – 36 ). Much of the current practice of medicine lacks moderate or high quality RCTs to address what treatment methods have demonstrated efficacy and much of the best practice guidelines remains based on consensus from experts ( 28 , 37 ). The reliance on high quality methodology in all types of studies will allow for continued improvement in the assessment of causal factors for health outcomes and the treatment of diseases.

Standards of research and reporting

There are many published standards for the design, execution and reporting of biomedical research, which can be found in Table 3 . The purpose and content of these standards and guidelines are to improve the quality of biomedical research which will result in providing sound conclusions to base medical decision making upon. There are published standards for categories of study designs such as observational studies (e.g. STROBE), interventional studies (e.g. CONSORT), diagnostic studies (e.g. STARD, QUADAS), systematic reviews and meta-analyses (e.g. PRISMA ), as well as others. The aim of these standards and guideline are to systematize and elevate the quality of biomedical research design, execution, and reporting.

Published standard for study design and reporting.

Consolidated Standards Of Reporting Trials (CONSORT, www.consort-statement.org ) are interventional study standards, a 25 item checklist and flowchart specifically designed for RCTs to standardize reporting of key elements including design, analysis and interpretation of the RCT.
Strengthening the Reporting of Observational studies in Epidemiology (STROBE, www.strobe-statement.org ) is a collection of guidelines specifically for standardization and improvement of the reporting of observational epidemiological research. There are specific subsets of the STROBE statement including molecular epidemiology (STROBE-ME), infectious diseases (STROBE-ID) and genetic association studies (STREGA).
Standards for Reporting Studies of Diagnos tic Accuracy (STARD, www.stard-statement.org ) is a 25 element checklist and flow diagram specifically designed for the reporting of diagnostic accuracy studies.
Quality assessment of diagnostic accuracy studies (QUADAS, www.bris.ac.uk/quadas ) is a quality assessment of diagnostic accuracy studies.
Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA, www.prisma-statement.org ) is a 27 element checklist and multiphase flow diagram to improve quality of reporting systematic reviews and meta-analyses. It replaces the QUOROM statement.
Consolidated criteria for reporting qualitative research (COREQ) is a 32 element checklist designed for reporting of qualitative data from interviews and focus groups.
Statistical Analyses and Methods in the Published Literature (SAMPL) is a guideline for statistical methods and analyses of all types of biomedical research.
Consensus-based Clinical Case Reporting Guideline Development (CARE, www.carestatement.org ) is a checklist comprised of 13 elements and is designed only for case reports.
Standards for Quality Improvement Reporting Excellence (SQUIRE, www.squire-statement.org ) are publication guidelines comprised of 19 elements, for authors aimed at quality improvement in health care reporting.
Consolidated Health Economic Evaluation Reporting Standards (CHEERS) is a 24 element checklist of reporting practices for economic evaluations of interventional studies.
Enhancing transparency in reporting the synthesis of qualitative research (ENTREQ) is a guideline specifically for standardizing and improving the reporting of qualitative biomedical research.

When designing or evaluating a study it may be helpful to review the applicable standards prior to executing and publishing the study. All published standards and guidelines are available on the web, and are updated based on current best practices as biomedical research evolves. Additionally, there is a network called “Enhancing the quality and transparency of health research” (EQUATOR, www.equator-network.org ) , which has guidelines and checklists for all standards reported in Table 3 and is continually updated with new study design or specialty specific standards.

The appropriate selection of a study design is only one element in successful research. The selection of a study design should incorporate consideration of costs, access to cases, identification of the exposure, the epidemiologic measures that are required, and the level of evidence that is currently published regarding the specific exposure-outcome relationship that is being assessed. Reviewing appropriate published standards when designing a study can substantially strengthen the execution and interpretation of study results.

Potential conflict of interest

None declared.

StarTribune

What happened when uber and lyft shut down in austin, texas.

A large regional city with a progressive bent wants to impose new rules on Uber and Lyft. The ridesharing giants threaten to leave the city. The dispute becomes the hottest issue in town. The Legislature gets involved.

It could be Minneapolis in 2024, as it tussles with Uber and Lyft over a minimum wage for drivers. But it's also Austin, Texas, in 2016.

Austin lost Uber and Lyft service for more than a year after the companies fought a city ordinance requiring drivers to be fingerprinted to protect passengers. The players, the locale and the politics may differ, but the final result could be the same.

Uber says it will cease operating in the Twin Cities, while Lyft claims it will shut down in Minneapolis if the pay minimums stand. Meanwhile, city and state elected leaders in Minnesota are frantically trying to craft a solution before the Legislature adjourns May 20.

Austin's experience shows how such a conflict can play out in a tech-savvy, car-dependent, party-loving town that famously embraces its weirdness. It's a story about a Democratic stronghold in ruby red Texas that took on two brazen companies offering a wildly popular service and winning in convincing fashion. But its victory was short-lived. Republican lawmakers overturned the new rules.

What hasn't changed since since then is that Uber and Lyft are still willing to leave town if they don't get their way. "Uber has changed a lot over the years, including how we make our case for positive regulations, but one thing has been consistent: leaving a city has never been a decision we've taken lightly," said Josh Gold, a company spokesman.

A safety issue

In 2015, about a year after Uber and Lyft began service in Austin, several cities in Texas adopted regulations requiring ridesharing companies to fingerprint drivers following several reports of drivers having sexually assaulted passengers.

"It was truly a safety issue for women," said Ann Kitchen, a City Council member who led a committee that crafted Austin's fingerprinting ordinance. "There was no reason for [Uber and Lyft] to not do it."

At the time, taxi, limousine, even pedicab, operators in Austin were fingerprinted as part of the city's licensing process. But not Uber and Lyft, which claimed their security screening process worked just fine.

Lyft says fingerprinting is "a discriminatory practice with outsized impacts on communities of color," said spokesperson CJ Macklin last week. "The fingerprint background check system is widely considered incomplete and inaccurate and a discriminatory practice when used as a basis to deny work."

When San Antonio adopted a fingerprinting ordinance in 2015, both ridesharing companies ended service, returning only after it was deemed voluntary. After Houston required fingerprinting, Lyft left, and Uber stayed on.

Both companies warned if Austin adopted a fingerprinting measure, they would leave. Despite that, the City Council adopted such an ordinance in late 2015.

The response to the new regulations was swift: A group backed by Uber and Lyft called Ridesharing Works for Austin gathered 65,000 signatures to force an election that would overturn the new ordinance. Called Proposition 1, or Prop 1, an election was set for that May.

Deals fall apart

Throughout the spring of 2016, then-Mayor Stephen Adler said he tried to broker a deal with Uber and Lyft by suggesting solutions.

Among them: the city fingerprinting Uber and Lyft drivers where they worked or lived for convenience sake; having the local tech community design a slider for the companies' apps indicating drivers who were fingerprinted; and crafting a "thumbs-up" seal of approval for drivers who had been fingerprinted. Adler even suggested a lottery with a Tesla as a prize to encourage drivers to get fingerprinted.

"We put together some pretty nifty, innovative ideas," he said. "They told us they would leave the city anyhow, which made no sense to us because we weren't asking them to do anything."

Adler is writing a book about his eight-year tenure as mayor that includes a chapter devoted to the Uber and Lyft rumpus. He said he wanted to show that "solutions can be worked out between new technologies and platforms in the sharing economy if companies are willing to work with the communities."

But Adler said he was repeatedly rebuffed by Uber and Lyft, which began to operate like the stodgy, change-resistant old-economy companies they routinely pilloried.

Prop 1 fatigue

As the Prop 1 campaign wore on, many Austin residents grew weary of the issue.

"You could not guess the number of ads that came from Uber and Lyft, they spent so much money, people just got annoyed," said Austin resident and former pedicab operator Chris Anderson. "Every day, you'd go out to your mailbox and there were 10 mailers in there. People got pissed."

Another coalition that supported fingerprinting, which included taxi companies and labor unions, sprouted up called "Our City. Our Safety. Our Choice." The group was co-founded by longtime Democratic political consultant David Butts, who contributed about $20,000 of his own money to the cause.

"It was an attempt by a corporation to run over a city," Butts said. "We weren't going to stand for it."

Uber and Lyft reportedly spent about $10 million on its campaign to overturn the fingerprinting ordinance, with the city shelling out less than $200,000.

Kitchen, the City Council member who led the fingerprinting effort, came under direct fire. Uber launched a service that featured horse and buggy rides in downtown Austin called "Kitchen's Uber." A flat fee of $50 was charged.

"Council Member Kitchen's plan would impose 19th-century regulations on 21st-century technology," an Uber spokesperson said.

"It was funny, except I didn't think it was funny at the time," Kitchen said last week. "It was just outrageous."

At the same time, there was a move to recall Kitchen. Uber and Lyft denied being a part of the recall effort — the political action committee leading the charge was traced to Republican operatives, according to the Austin American-Statesman. No recall election was ever held.

Prop 1 ultimately failed as well, as city voters overwhelmingly defeated Uber and Lyft's attempt to overturn fingerprinting by a 12-point margin.

In response, Uber and Lyft shut down service within two days in Austin.

Alternatives sought

With no ridesharing, diminished taxi service and minimal public transit, Austin was ripe for new transportation solutions, especially since thousands of former Uber and Lyft drivers were available for work.

Within months, a nonprofit rideshare company was formed by local tech entrepreneurs with city support called RideAustin, which permitted customers to round up their fares for local charities. Boston-based Fasten entered town, as well as several others.

Jeff Kirk, an Austin-based rideshare strategist, said about 14 rideshare apps surfaced at various times after Uber and Lyft departed. Service was often spotty. Ultimately all of them shut down, although new apps have cropped up more recently.

A big test came for the alternative ridesharing apps during the 2017 South by Southwest conference and festival, a magnet for thousands of celebrities, techies and creative thinkers. One rainy Saturday night at the height of the event, many of the apps crashed.

"It was completely impossible to get a ride, and all of the out-of-towners and journalists covered it," Kirk said. "There were a lot of pissed-off techies."

But Kirk said Minneapolis appears to have some promising rideshare players entering the market. "If there are alternatives that are actually working, I'm wondering if more and more cities will essentially do the same thing as Minneapolis. They could present a serious threat to Uber and Lyft and one that is long overdue."

Legislature enters fray

Most involved in the Prop 1 battle in Austin suspected the Republican-controlled Legislature would pass a bill that preempted local ridesharing ordinances — and that's exactly what happened.

"All Uber and Lyft had to do is drag some campaign contributions around the statehouse, [legislators] are like feral cats in heat when that happens," said Butts.

As Republican Gov. Greg Abbott signed legislation in 2017 usurping local ridesharing regulations in more than 20 communities throughout the state, he declared, "This is freedom for every Texan."

Within hours, Uber's and Lyft's apps in Austin were turned back on, a move that was met with "joy and bitterness," according to the local newspaper.

When asked whether Uber and Lyft are bluffing in Minneapolis, Kitchen (and others) said they're not.

"But the thing about it is: Who cares? Our community did not suffer from them being gone," she said. "The community said no, they would not be bullied, and created RideAustin to take care of drivers and passengers.

"I was proud of our community for standing up to them."

RideAustin, which provided nearly 3 million rides , struggled after Uber and Lyft returned to Austin. Then the pandemic hit, and it closed up shop in 2020. It has open sourced its software platform so others may start their own ridesharing apps.

Transportation reporter Janet Moore covers trains, planes, automobiles, buses, bikes and pedestrians. Moore has been with the Star Tribune for 21 years, previously covering business news, including the retail, medical device and commercial real estate industries.

Josie Albertson-Grove covers the western Twin Cities suburbs for the Star Tribune.

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What Is an Observational Study?
There are three main types of observational studies: cohort studies, case-control studies, and cross-sectional studies. Cohort studies. Cohort studies are more longitudinal in nature, as they follow a group of participants over a period of time. Members of the cohort are selected because of a shared characteristic, such as smoking, and they ...
Observational studies and their utility for practice
Observational studies provide critical descriptive data and information on long-term efficacy and safety that clinical trials cannot provide, at generally much less expense. Observational studies include case reports and case series, ecological studies, cross-sectional studies, case-control studies and cohort studies. ...
Observational Studies: Cohort and Case-Control Studies
Cohort studies and case-control studies are two primary types of observational studies that aid in evaluating associations between diseases and exposures. In this review article, we describe these study designs, methodological issues, and provide examples from the plastic surgery literature. Keywords: observational studies, case-control study ...
Observational Study Designs: Synopsis for Selecting an Appropriate
The observational design is subdivided into descriptive, including cross-sectional, case report or case series, and correlational, and analytic which includes cross-section, case-control, and cohort studies. Each research design has its uses and points of strength and limitations. The aim of this article to provide a simplified approach for the ...
PDF Case Study Observational Research: A Framework for Conducting Case
characteristics of case study observational research, a modified form of Yin's 2014 model of case study research the authors used in a study exploring interprofessional collaboration in primary care. In this approach, observation data are positioned as the central component of the research design.
Observational Case Studies
An observational case study is a study of a real-world case without performing an intervention. Measurement may influence the measured phenomena, but as in all forms of research, the researcher tries to restrict this to a minimum. The researcher may study a sample of two or even more cases, but the goal of case study research is not to acquire ...
What is Observational Study Design and What Types
Case Control Observational Study. Researchers in case control studies identify individuals with an existing health issue or condition, or "cases," along with a similar group without the condition, or "controls." These two groups are then compared to identify predictors and outcomes. This type of study is helpful to generate a hypothesis ...
Case Study Observational Research: A Framework for Conducting Case
Observation methods have the potential to reach beyond other methods that rely largely or solely on self-report. This article describes the distinctive characteristics of case study observational research, a modified form of Yin's 2014 model of case study research the authors used in a study exploring interprofessional collaboration in primary ...
Observational studies: a review of study designs, challenges and
Cohort studies follow one group that is exposed to an intervention of interest and another group that is non-exposed to determine the occurrence of the outcome (the relative risk). Cohort studies can examine multiple outcomes of a single exposure. Case-control studies compare the proportion of cases with a specific exposure to the proportion of controls with the same exposure (the odds ratio).
What is an Observational Study: Definition & Examples
In an observational study vs experiment, the researchers only observe the subjects and do not interfere or try to influence the outcomes. Skip to secondary menu; ... Case-Control Study: A retrospective observational study that compares two existing groups—the case group with the condition and the control group without it. Researchers compare ...
6.6: Observational Research
A case study is an in-depth examination of an individual. Sometimes case studies are also completed on social units (e.g., a cult) and events (e.g., a natural disaster). ... So, as with all observational methods, case studies do not permit determination of causation. In addition, because case studies are often of a single individual, and ...
Observational research methods—Cohort studies, cross sectional studies
Cohort, cross sectional, and case-control studies are collectively referred to as observational studies. Observational studies are often the only practicable method of answering questions of aetiology, the natural history and treatment of rare conditions and instances where a randomised controlled trial might be unethical.
6.5 Observational Research
Like many observational research methods, case studies tend to be more qualitative in nature. Case study methods involve an in-depth, and often a longitudinal examination of an individual. Depending on the focus of the case study, individuals may or may not be observed in their natural setting. If the natural setting is not what is of interest ...
Randomized, Controlled Trials, Observational Studies, and the Hierarchy
Current criticisms of observational studies involve, in addition to trials with historical controls, cohort studies with concurrent selection of control subjects, as well as case-control designs.
Observational study
An observational study would typically start with a group of symptomatic subjects and work backwards to find those who were given the medication and later developed the symptoms. Thus a subset of the treated group was determined based on the presence of symptoms, instead of by random assignment. ... Case-control study: study originally ...
Observational designs for real-world evidence studies
The "fit-for-purpose" observational study designs include descriptive, case-control, cross-sectional, and cohort. This article focuses on the advantages and disadvantages including the inherent bias of each study design. The RWE study decision guide has also been provided to aid the selection of appropriate study designs.
Observational studies: cohort and case-control studies
Cohort studies and case-control studies are two primary types of observational studies that aid in evaluating associations between diseases and exposures. In this review article, the authors describe these study designs and methodologic issues, and provide examples from the plastic surgery literature.
Case Study Methodology of Qualitative Research: Key Attributes and
A case study is one of the most commonly used methodologies of social research. This article attempts to look into the various dimensions of a case study research strategy, the different epistemological strands which determine the particular case study type and approach adopted in the field, discusses the factors which can enhance the effectiveness of a case study research, and the debate ...
Case Study Observational Research: A Framework for Conducting Case
The distinctive characteristics of case study observational research are described, a modified form of Yin's 2014 model ofCase study research the authors used in a study exploring interprofessional collaboration in primary care, where contextual influences are of primary concern. Case study research is a comprehensive method that incorporates multiple sources of data to provide detailed ...
Observation Methods: Naturalistic, Participant and Controlled
Like case studies, naturalistic observation is often used to generate new ideas. Because it gives the researcher the opportunity to study the total situation, it often suggests avenues of inquiry not thought of before. The ability to capture actual behaviors as they unfold in real-time, analyze sequential patterns of interactions, measure base ...
Perioperative serum syndecan-1 concentrations in patients who underwent
The objectives of this study were to measure perioperative serum syndecan-1 concentrations in patients who underwent CVS with CPB, evaluate their trends, and determine their association with pAKI. Methods. This was a descriptive and case‒control study conducted at the National University Hospital.
Appropriate use of medication among home care adult cancer patients at
Medications are commonly used for symptom control in cancer patients at the end of life. This study aimed to evaluate medication utilization among home care palliative patients with cancer at the end of life and assess the appropriateness of these medications. This retrospective observational study included adult cancer patients who received home care in 2020.
Evidence‐based medicine—When observational studies are better than
In the traditional hierarchy of study designs, the randomized controlled trial (RCT) is placed on top, followed by cohort studies, case‐control studies, case reports and case series. 2 However, the foremost consideration for the choice of study design should be the research question. For some research questions, an RCT might be the most ...
Molar root canal treatment performed by undergraduate dental students
Molar root canal treatment (RCT) is challenging and requires training and specific skills. Rotary instrumentation (RI) reduces the time needed for instrumentation but may increase the risk of certain procedural errors. The aims of this study were to evaluate the quality of molar RCTs provided by undergraduate students, to compare the prevalence of procedural errors following manual and RI, and ...
What's at stake as the Supreme Court hears case about abortion in
The case, known as Moyle v.United States (Mike Moyle is the speaker of the Idaho House), has major implications on everything from what emergency care is available in states with abortion bans to ...
Cross ventilation; A traditional solution for better indoor air quality
This study aims to investigate the factor of good indoor air quality (IAQ) in Masjid Kampung Laut, and to prove the hypothesis that it was because of the cross ventilation system within the building. The methodology used in the investigation is mix method, involving several ways including measurement on site, interview, direct observation ...
Study designs: Part 3
In analytical observational studies, researchers try to establish an association between exposure (s) and outcome (s). Depending on the direction of enquiry, these studies can be directed forwards (cohort studies) or backwards (case-control studies). In this article, we examine the key features of these two types of studies.
'Zombie deer disease': Study of 2 hunter deaths raises concerns
The 2022 case did prove that CWD could infect humans. But scientists and health officials have been concerned that CWD could jump to humans as mad cow disease did in the United Kingdom in the ...
Observational and interventional study design types; an overview
Observational study designs include ecological designs, cross sectional, case-control, case-crossover, retrospective and prospective cohorts. An important subset of observational studies is diagnostic study designs, which evaluate the accuracy of diagnostic procedures and tests as compared to other diagnostic measures.
What happened when Uber and Lyft shut down in Austin, Texas
A large regional city with a progressive bent wants to impose new rules on Uber and Lyft. The ridesharing giants threaten to leave the city. The dispute becomes the hottest issue in town. The ...