blind study in research

Double-Blind Experimental Study And Procedure Explained

Julia Simkus

Editor at Simply Psychology

BA (Hons) Psychology, Princeton University

Julia Simkus is a graduate of Princeton University with a Bachelor of Arts in Psychology. She is currently studying for a Master's Degree in Counseling for Mental Health and Wellness in September 2023. Julia's research has been published in peer reviewed journals.

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What is a Blinded Study?

• Binding, or masking, refers to withholding information regarding treatment allocation from one or more participants in a clinical research study, typically in randomized control trials .
• A blinded study prevents the participants from knowing about their treatment to avoid bias in the research. Any information that can influence the subjects is withheld until the completion of the research.
• Blinding can be imposed on any participant in an experiment, including researchers, data collectors, evaluators, technicians, and data analysts. 
• Good blinding can eliminate experimental biases arising from the subjects’ expectations, observer bias, confirmation bias, researcher bias, observer’s effect on the participants, and other biases that may occur in a research test.
• Studies may use single-, double- or triple-blinding. A trial that is not blinded is called an open trial.

Double-Blind Studies

Double-blind studies are those in which neither the participants nor the experimenters know who is receiving a particular treatment.

Double blinding prevents bias in research results, specifically due to demand characteristics or the placebo effect.

Demand characteristics are subtle cues from researchers that can inform the participants of what the experimenter expects to find or how participants are expected to behave.

If participants know which group they are assigned to, they might change their behavior in a way that would influence the results. Similarly, if a researcher knows which group a participant is assigned to, they might act in a way that reveals the assignment or influences the results.

Double-blinding attempts to prevent these risks, ensuring that any difference(s) between the groups can be attributed to the treatment. 

On the other hand, single-blind studies are those in which the experimenters are aware of which participants are receiving the treatment while the participants are unaware.

Single-blind studies are beneficial because they reduce the risk of errors due to subject expectations. However, single-blind studies do not prevent observer bias, confirmation bias , or bias due to demand characteristics.

Because the experiments are aware of which participants are receiving which treatments, they are more likely to reveal subtle clues that can accidentally influence the research outcome.

Double-blind studies are considered the gold standard in research because they help to control for experimental biases arising from the subjects’ expectations and experimenter biases that emerge when the researchers unknowingly influence how the subjects respond or how the data is collected.

Using the double-blind method improves the credibility and validity of a study .

Example Double-Blind Studies

Rostock and Huber (2014) used a randomized, placebo-controlled, double-blind study to investigate the immunological effects of mistletoe extract. However, their study showed that double-blinding is impossible when the investigated therapy has obvious side effects. 

Using a double-blind study, Kobak et al. (2005) found that S t John’s wort ( Hypericum perforatum ) is not an efficacious treatment for anxiety disorder, specifically OCD.

Using the Yale–Brown Obsessive–Compulsive Scale (Y-BOCS), they found that the mean change with St John’s wort was not significantly different from the mean change found with placebo. 

Cakir et al. (2014) conducted a randomized, controlled, and double-blind study to test the efficacy of therapeutic ultrasound for managing knee osteoarthritis.

They found that all assessment parameters significantly improved in all groups without a significant difference, suggesting that therapeutic ultrasound provided no additional benefit in improving pain and functions in addition to exercise training.

Using a randomized double-blind study, Papachristofilou et al. (2021) found that whole-lung LDRT failed to improve clinical outcomes in critically ill patients admitted to the intensive care unit requiring mechanical ventilation for COVID-19 pneumonia.

Double-Blinding Procedure

Double blinding is typically used in clinical research studies or clinical trials to test the safety and efficacy of various biomedical and behavioral interventions.

In such studies, researchers tend to use a placebo. A placebo is an inactive substance, typically a sugar pill, that is designed to look like the drug or treatment being tested but has no effect on the individual taking it. 

The placebo pill was given to the participants who were randomly assigned to the control group. This group serves as a baseline to determine if exposure to the treatment had any significant effects.

Those randomly assigned to the experimental group are given the actual treatment in question. Data is collected from both groups and then compared to determine if the treatment had any impact on the dependent variable.

All participants in the study will take a pill or receive a treatment, but only some of them will receive the real treatment under investigation while the rest of the subjects will receive a placebo. 

With double blinding, neither the participants nor the experimenters will have any idea who receives the real drug and who receives the placebo. 

For Example

A common example of double-blinding is clinical studies that are conducted to test new drugs.

In these studies, researchers will use random assignment to allocate patients into one of three groups: the treatment/experimental group (which receives the drug), the placebo group (which receives an inactive substance that looks identical to the treatment but has no drug in it), and the control group (which receives no treatment).

Both participants and researchers are kept unaware of which participants are allocated to which of the three groups.

The effects of the drug are measured by recording any symptoms noticed in the patients.

Once the study is unblinded, and the researchers and participants are made aware of who is in which group, the data can be analyzed to determine whether the drug had effects that were not seen in the placebo or control group, but only in the experimental group. 

Double-blind studies can also be beneficial in nonmedical interventions, such as psychotherapIes.

Reduces risk of bias

Double-blinding can eliminate, or significantly reduce, both observer bias and participant biases.

Because both the researcher and the subjects are unaware of the treatment assignments, it is difficult for their expectations or behaviors to influence the study.

Results can be duplicated

The results of a double-blind study can be duplicated, enabling other researchers to follow the same processes, apply the same test item, and compare their results with the control group.

If the results are similar, then it adds more validity to the ability of a medication or treatment to provide benefits. 

It tests for three groups

Double-blind studies usually involve three groups of subjects: the treatment group, the placebo group, and the control group.

The treatment and placebo groups are both given the test item, although the researcher does not know which group is getting real treatment or placebo treatment.

The control group doesn’t receive anything because it serves as the baseline against which the other two groups are compared.

This is an advantage because if subjects in the placebo group improved more than the subjects in the control group, then researchers can conclude that the treatment administered worked.

Applicable across multiple industries

Double-blind studies can be used across multiple industries, such as agriculture, biology, chemistry, engineering, and social sciences.

Double-blind studies are used primarily by the pharmaceutical industry because researchers can look directly at the impact of medications. 

Disadvantages

Inability to blind.

In some types of research, specifically therapeutic, the treatment cannot always be disguised from the participant or the experimenter. In these cases, you must rely on other methods to reduce bias.

Additionally, imposing blinding may be impossible or unethical for some studies. 

Double-blinding can be expensive because the researcher has to examine all the possible variables and may have to use different groups to gather enough data. 

Small Sample Size

Most double-blind studies are too small to provide a representative sample. To be effective, it is generally recommended that double-blind trials include around 100-300 participants.

Studies involving fewer than 30 participants generally can’t provide proof of a theory. 

Negative Reaction to Placebo

In some instances, participants can have adverse reactions to the placebo, even producing unwanted side effects as if they were taking a real medication. 

It doesn’t reflect real-life circumstances

When participants receive treatment or medication in a double-blind placebo study, each individual is told that the item in question might be real medication or a placebo.

This artificial situation does not represent real-life circumstances because when a patient receives a pill after going to the doctor in the real-world, they are told that the product is actual medicine intended to benefit them.

When situations don’t feel realistic to a participant, then the quality of the data can decrease exponentially.

What is the difference between a single-blind, double-blind, and triple-blind study?

In a single-blind study, the experimenters are aware of which participants are receiving the treatment while the participants are unaware.

In a double-blind study, neither the patients nor the researchers know which study group the patients are in. In a triple-blind study, neither the patients, clinicians, nor the people carrying out the statistical analysis know which treatment the subjects had.

Is a double-blind study the same as a randomized clinical trial?

Yes, a double-blind study is a form of a randomized clinical trial in which neither the participants nor the researcher know if a subject is receiving the experimental treatment, a standard treatment, or a placebo.

Are double-blind studies ethical?

Double blinding is ethical only if it serves a scientific purpose. In most circumstances, it is unethical to conduct a double-blind placebo controlled trial where standard therapy exists.

What is the purpose of randomization using double blinding?

Randomization with blinding avoids reporting bias, since no one knows who is being treated and who is not, and thus all treatment groups should be treated the same. This reduces the influence of confounding variables and improves the reliability of clinical trial results.

Why are double-blind experiments considered the gold standard?

Randomized double-blind placebo control studies are considered the “gold standard” of epidemiologic studies as they provide the strongest possible evidence of causality.

Additionally, because neither the participants nor the researchers know who has received what treatment, double-blind studies minimize the placebo effect and significantly reduce bias.

Can blinding be used in qualitative studies?

Yes, blinding is used in qualitative studies .

Cakir, S., Hepguler, S., Ozturk, C., Korkmaz, M., Isleten, B., & Atamaz, F. C. (2014). Efficacy of therapeutic ultrasound for the management of knee osteoarthritis: a randomized, controlled, and double-blind study. American journal of physical medicine & rehabilitation , 93 (5), 405-412.

Kobak, K. A., Taylor, L. V., Bystritsky, A., Kohlenberg, C. J., Greist, J. H., Tucker, P., … & Vapnik, T. (2005). St John’s wort versus placebo in obsessive–compulsive disorder: results from a double-blind study. International Clinical Psychopharmacology , 20 (6), 299-304.

Papachristofilou, A., Finazzi, T., Blum, A., Zehnder, T., Zellweger, N., Lustenberger, J., … & Siegemund, M. (2021). Low-dose radiation therapy for severe COVID-19 pneumonia: a randomized double-blind study. International Journal of Radiation Oncology* Biology* Physics , 110 (5), 1274-1282. Rostock, M., & Huber, R. (2004). Randomized and double-blind studies–demands and reality as demonstrated by two examples of mistletoe research. Complementary Medicine Research , 11 (Suppl. 1), 18-22.

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• What Is a Double-Blind Study? | Introduction & Examples

What Is a Double-Blind Study? | Introduction & Examples

Published on 6 May 2022 by Lauren Thomas . Revised on 17 October 2022.

In experimental research , subjects are randomly assigned to either a treatment or control group . A double-blind study withholds each subject’s group assignment from both the participant and the researcher performing the experiment.

If participants know which group they are assigned to, there is a risk that they might change their behaviour in a way that would influence the results. If researchers know which group a participant is assigned to, they might act in a way that reveals the assignment or directly influences the results.

Double blinding guards against these risks, ensuring that any difference between the groups can be attributed to the treatment.

Table of contents

Different types of blinding, importance of blinding, frequently asked questions about double-blind studies.

Blinding means withholding which group each participant has been assigned to. Studies may use single, double or triple blinding.

Single blinding occurs in many different kinds of studies, but double and triple blinding are mainly used in medical research.

Single blinding

If participants know whether they were assigned to the treatment or control group, they might modify their behaviour as a result, potentially changing their eventual outcome.

In a single-blind experiment, participants do not know which group they have been placed in until after the experiment has finished.

If participants in the control group realise they have received a fake vaccine and are not protected against the flu, they might modify their behaviour in ways that lower their chances of becoming sick – frequently washing their hands, avoiding crowded areas, etc. This behaviour could narrow the gap in sickness rates between the control group and the treatment group, thus making the vaccine seem less effective than it really is.

Double blinding

When the researchers administering the experimental treatment are aware of each participant’s group assignment, they may inadvertently treat those in the control group differently from those in the treatment group. This could reveal to participants their group assignment, or even directly influence the outcome itself.

In double-blind experiments, the group assignment is hidden from both the participant and the person administering the experiment.

If these experimenters knew which vaccines were real and which were fake, they might accidentally reveal this information to the participants, thus influencing their behaviour and indirectly the results.

They could even directly influence the results. For instance, if experimenters expect the vaccine to result in lower levels of flu symptoms, they might accidentally measure symptoms incorrectly, thus making the vaccine appear more effective than it really is.

Triple blinding

Although rarely implemented, triple-blind studies occur when group assignment is hidden not only from participants and administrators, but also from those tasked with analysing the data after the experiment has concluded.

Researchers may expect a certain outcome and analyse the data in different ways until they arrive at the outcome they expected, even if it is merely a result of chance.

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Blinding helps ensure a study’s internal validity , or the extent to which you can be confident any link you find in your study is a true cause-and-effect relationship.

Since non-blinded studies can result in participants modifying their behaviour or researchers finding effects that do not really exist, blinding is an important tool to avoid bias in all types of scientific research.

Risk of unblinding

Unblinding occurs when researchers have blinded participants or experimenters, but they become aware of who received which treatment before the experiment has ended.

This may result in the same outcomes as would have occurred without any blinding.

You randomly assign some students to the new programme (the treatment group), while others are instructed with a standard programme (the control group). You use single blinding: you do not inform students whether they are receiving the new instruction programme or the standard one.

If students become aware of which programme they have been assigned to – for example, by talking to previous students about the content of the programme – they may change their behaviour. Students in the control group might work harder on their reading skills to make up for not receiving the new programme, or conversely to put in less effort instead since they might believe the other students will do better than them anyway.

Inability to blind

Double or triple blinding is often not possible. While medical experiments can usually use a placebo or fake treatment for blinding, in other types of research, the treatment sometimes cannot be disguised from either the participant or the experimenter. For example, many treatments that physical therapists perform cannot be faked.

In such cases, you must rely on other methods to reduce bias.

• Running a single- rather than double- or triple-blind study. Sometimes, although you might not be able to hide what each subject receives, you can still prevent them from knowing whether they are in the treatment or control group. Single blinding is particularly useful in non-medical studies where you cannot use a placebo in the control group.
• Relying on objective measures that participants and experimenters have less control over rather than subjective ones, like measuring fever rather than self-reported pain. This should reduce the possibility that participants or experimenters could influence the results.
• Pre-registering data analysis techniques. This will prevent researchers from trying different measures of analysis until they arrive at the answer they’re expecting.

Blinding means hiding who is assigned to the treatment group and who is assigned to the control group in an experiment .

Blinding is important to reduce bias (e.g., observer bias , demand characteristics ) and ensure a study’s internal validity .

If participants know whether they are in a control or treatment group , they may adjust their behaviour in ways that affect the outcome that researchers are trying to measure. If the people administering the treatment are aware of group assignment, they may treat participants differently and thus directly or indirectly influence the final results.

• In a single-blind study , only the participants are blinded.
• In a double-blind study , both participants and experimenters are blinded.
• In a triple-blind study , the assignment is hidden not only from participants and experimenters, but also from the researchers analysing the data.

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Blinding in clinical trials and other studies

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• Simon J Day a , manager, clinical biometrics ,
• Douglas G Altman b , professor of statistics in medicine
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Human behaviour is influenced by what we know or believe. In research there is a particular risk of expectation influencing findings, most obviously when there is some subjectivity in assessment, leading to biased results. Blinding (sometimes called masking) is used to try to eliminate such bias.

It is a tenet of randomised controlled trials that the treatment allocation for each patient is not revealed until the patient has irrevocably been entered into the trial, to avoid selection bias. This sort of blinding, better referred to as allocation concealment, will be discussed in a future statistics note. In controlled trials the term blinding, and in particular “double blind,” usually refers to keeping study participants, those involved with their management, and those collecting and analysing clinical data unaware of the assigned treatment, so that they should not be influenced by that knowledge.

The relevance of blinding will vary according to circumstances. Blinding patients to the treatment they have received in a controlled trial is particularly important when the response criteria are subjective, such as alleviation of pain, but less important for objective criteria, such as death. Similarly, medical staff caring for patients in a randomised trial should be blinded to treatment allocation to minimise possible bias in patient management and in assessing disease status. For example, the decision to withdraw a patient from a study or to adjust the dose of medication could easily be influenced by knowledge of which treatment group the patient has been assigned to.

In a double blind trial neither the patient nor the caregivers are aware of the treatment assignment. Blinding means more than just keeping the name of the treatment hidden. Patients may well see the treatment being given to patients in the other treatment group(s), and the appearance of the drug used in the study could give a clue to its identity. Differences in taste, smell, or mode of delivery may also influence efficacy, so these aspects should be identical for each treatment group. Even colour of medication has been shown to influence efficacy. 1

In studies comparing two active compounds, blinding is possible using the “double dummy” method. For example, if we want to compare two medicines, one presented as green tablets and one as pink capsules, we could also supply green placebo tablets and pink placebo capsules so that both groups of patients would take one green tablet and one pink capsule.

Blinding is certainly not always easy or possible. Single blind trials (where either only the investigator or only the patient is blind to the allocation) are sometimes unavoidable, as are open (non-blind) trials. In trials of different styles of patient management, surgical procedures, or alternative therapies, full blinding is often impossible.

In a double blind trial it is implicit that the assessment of patient outcome is done in ignorance of the treatment received. Such blind assessment of outcome can often also be achieved in trials which are open (non-blinded). For example, lesions can be photographed before and after treatment and assessed by someone not involved in running the trial. Indeed, blind assessment of outcome may be more important than blinding the administration of the treatment, especially when the outcome measure involves subjectivity. Despite the best intentions, some treatments have unintended effects that are so specific that their occurrence will inevitably identify the treatment received to both the patient and the medical staff. Blind assessment of outcome is especially useful when this is a risk.

In epidemiological studies it is preferable that the identification of “cases” as opposed to “controls” be kept secret while researchers are determining each subject's exposure to potential risk factors. In many such studies blinding is impossible because exposure can be discovered only by interviewing the study participants, who obviously know whether or not they are a case. The risk of differential recall of important disease related events between cases and controls must then be recognised and if possible investigated. 2 As a minimum the sensitivity of the results to differential recall should be considered. Blinded assessment of patient outcome may also be valuable in other epidemiological studies, such as cohort studies.

Blinding is important in other types of research too. For example, in studies to evaluate the performance of a diagnostic test those performing the test must be unaware of the true diagnosis. In studies to evaluate the reproducibility of a measurement technique the observers must be unaware of their previous measurement(s) on the same individual.

We have emphasised the risks of bias if adequate blinding is not used. This may seem to be challenging the integrity of researchers and patients, but bias associated with knowing the treatment is often subconscious. On average, randomised trials that have not used appropriate levels of blinding show larger treatment effects than blinded studies. 3 Similarly, diagnostic test performance is overestimated when the reference test is interpreted with knowledge of the test result. 4 Blinding makes it difficult to bias results intentionally or unintentionally and so helps ensure the credibility of study conclusions.

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Double-Blind Studies in Research

Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book."

Emily is a board-certified science editor who has worked with top digital publishing brands like Voices for Biodiversity, Study.com, GoodTherapy, Vox, and Verywell.

A double-blind study is one in which neither the participants nor the experimenters know who is receiving a particular treatment. This procedure is utilized to prevent bias in research results. Double-blind studies are particularly useful for preventing bias due to demand characteristics or the placebo effect .

For example, let's imagine that researchers are investigating the effects of a new drug. In a double-blind study, the researchers who interact with the participants would not know who was receiving the actual drug and who was receiving a placebo.

A Closer Look at Double-Blind Studies

Let’s take a closer look at what we mean by a double-blind study and how this type of procedure works. As mentioned previously, double-blind indicates that the participants and the experimenters are unaware of who is receiving the real treatment. What exactly do we mean by ‘treatment'? In a psychology experiment, the treatment is the level of the independent variable that the experimenters are manipulating.

This can be contrasted with a single-blind study in which the experimenters are aware of which participants are receiving the treatment while the participants remain unaware.

In such studies, researchers may use what is known as a placebo. A placebo is an inert substance, such as a sugar pill, that has no effect on the individual taking it. The placebo pill is given to participants who are randomly assigned to the control group. A control group is a subset of participants who are not exposed to any levels of the independent variable . This group serves as a baseline to determine if exposure to the independent variable had any significant effects.

Those randomly assigned to the experimental group are given the treatment in question. Data collected from both groups are then compared to determine if the treatment had some impact on the dependent variable .

All participants in the study will take a pill, but only some of them will receive the real drug under investigation. The rest of the subjects will receive an inactive placebo. With a double-blind study, the participants and the experimenters have no idea who is receiving the real drug and who is receiving the sugar pill.

Double-blind experiments are simply not possible in some scenarios. For example, in an experiment looking at which type of psychotherapy is the most effective, it would be impossible to keep participants in the dark about whether or not they actually received therapy.

Reasons to Use a Double-Blind Study

So why would researchers opt for such a procedure? There are a couple of important reasons.

• First, since the participants do not know which group they are in, their beliefs about the treatment are less likely to influence the outcome.
• Second, since researchers are unaware of which subjects are receiving the real treatment, they are less likely to accidentally reveal subtle clues that might influence the outcome of the research.  

The double-blind procedure helps minimize the possible effects of experimenter bias.   Such biases often involve the researchers unknowingly influencing the results during the administration or data collection stages of the experiment. Researchers sometimes have subjective feelings and biases that might have an influence on how the subjects respond or how the data is collected.

In one research article, randomized double-blind placebo studies were identified as the "gold standard" when it comes to intervention-based studies.   One of the reasons for this is the fact that random assignment reduces the influence of confounding variables.

Imagine that researchers want to determine if consuming energy bars before a demanding athletic event leads to an improvement in performance. The researchers might begin by forming a pool of participants that are fairly equivalent regarding athletic ability. Some participants are randomly assigned to a control group while others are randomly assigned to the experimental group.

Participants are then be asked to eat an energy bar. All of the bars are packaged the same, but some are sports bars while others are simply bar-shaped brownies. The real energy bars contain high levels of protein and vitamins, while the placebo bars do not.

Because this is a double-blind study, neither the participants nor the experimenters know who is consuming the real energy bars and who is consuming the placebo bars.

The participants then complete a predetermined athletic task, and researchers collect data performance. Once all the data has been obtained, researchers can then compare the results of each group and determine if the independent variable had any impact on the dependent variable.  

A Word From Verywell

A double-blind study can be a useful research tool in psychology and other scientific areas. By keeping both the experimenters and the participants blind, bias is less likely to influence the results of the experiment. 

A double-blind experiment can be set up when the lead experimenter sets up the study but then has a colleague (such as a graduate student) collect the data from participants. The type of study that researchers decide to use, however, may depend upon a variety of factors, including characteristics of the situation, the participants, and the nature of the hypothesis under examination.

National Institutes of Health. FAQs About Clinical Studies .

Misra S. Randomized double blind placebo control studies, the "Gold Standard" in intervention based studies . Indian J Sex Transm Dis AIDS . 2012;33(2):131-4. doi:10.4103/2589-0557.102130

Goodwin, CJ. Research In Psychology: Methods and Design . New York: John Wiley & Sons; 2010.

Kalat, JW. Introduction to Psychology . Boston, MA: Cengage Learning; 2017.

By Kendra Cherry, MSEd Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book."

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Double Blind Study – Blinded Experiments

In science and medicine, a blind study or blind experiment is one in which information about the study is withheld from the participants until the experiment ends. The purpose of blinding an experiment is reducing bias, which is a type of error . Sometimes blinding is impractical or unethical, but in many experiments it improves the validity of results. Here is a look at the types of blinding and potentials problems that arise.

Single Blind, Double Blind, and Triple Blind Studies

The three types of blinding are single blinding, double blinding, and triple blinding:

Single Blind Study

In a single blind study , the researchers and analysis team know who gets a treatment, but the experimental subjects do not. In other words, the people performing the study know what the independent variable is and how it is being tested. The subjects are unaware whether they are receiving a placebo or a treatment. They may even be unaware what, exactly, is being studied.

Example: Violin Study

For example, consider an experiment that tests whether or not violinists can tell the difference a Stradivarius violin (generally regarded as superior) and a modern violin. The researchers know the type of violin they hand to a violinist, but the musician does not (is blind). In case you’re curious, in an actual experiment performed by Claudia Fritz and Joseph Curtin, it turned out violinists actually can’t tell the instruments apart.

Double Blind Study

In a double blind study, neither the researchers nor subjects know which group receives a treatment and which gets a placebo .

Example: Drug Trial

Many drug trials are double-blinded, where neither the doctor nor patient knows whether the drug or a placebo is administered. So, who gets the drug or the placebo is randomly assigned (without the doctor knowing who gets what). The inactive ingredients, color, and size of a pill (for example) are the same whether it is the treatment or placebo.

Triple Blind Study

A triple blind study includes an additional level of blinding. So, the data analysis team or the group overseeing an experiment is blind, in addition to the researchers and subjects.

Example: Vaccine Study

Triple blind studies are common as part of the vaccine approval process. Here, the people who analyze vaccine effectiveness collate data from many test sites and are unaware of which group a participant belongs to.

Some guidelines advocate for removing terms like “single blind” and “double blind” because they do not inherently describe which party is blinded. For example, a double blind study could mean the subjects and scientists are blind or it could mean the subjects and assessors are blind. When you describe blinding in an experiment, report who is blinded and what information is concealed.

The point of blinding is minimizing bias. Subjects have expectations if they know they receive a placebo versus a treatment. And, researchers have expectations regarding the expected outcome. For example, confirmation bias occurs when an investigator favors outcomes that support pre-existing research or the scientist’s own beliefs.

Unblinding is when masked information becomes available. In experiments with humans, intentional unblinding after a study concludes is typical. This way, a subject knows whether or not they received a treatment or placebo. Unblinding after a study concludes does not introduce bias because the data has already been collected and analyzed.

However, premature unblinding also occurs. For example, a doctor reviewing bloodwork often figures out who is getting a treatment and who is getting a placebo. Similarly, patients feeling an effect from a pill or injection suspect they are in the treatment group. One safeguard against this is an active placebo. An active placebo causes side effects, so it’s harder to tell treatment and placebo groups apart just based on how a patient feels.

Although premature unblinding affects the outcome of the results, it isn’t usually reported. This is a problem because unintentional unblinding favors false positives, at least in medicine. For example, if subjects believe they are receiving treatment, they often feel better even if a therapy isn’t effective. Premature unblinding is one of the issues at the heart of the debate about whether or not antidepressants are effective. But, it applies to all blind studies.

Uses of Blind Studies

Of course, blind studies are valuable in medicine and scientific research. But, they also have other applications.

For example, in a police lineup, having an officer familiar with the suspects can influence a witness’s selection. A better option is a blind procedure, using an office who does not know a suspect’s identity. Product developers routinely use blind studies for determining consumer preference. Orchestras use blind judging for auditions. Some employers and educational institutions use blind data for application selection.

• Bello, Segun; Moustgaard, Helene; Hróbjartsson, Asbjørn (October 2014). “The risk of unblinding was infrequently and incompletely reported in 300 randomized clinical trial publications”. Journal of Clinical Epidemiology . 67 (10): 1059–1069. doi: 10.1016/j.jclinepi.2014.05.007
• Daston, L. (2005). “Scientific Error and the Ethos of Belief”. Social Research . 72 (1): 18. doi: 10.1353/sor.2005.0016
• MacCoun, Robert; Perlmutter, Saul (2015). “Blind analysis: Hide results to seek the truth”. Nature . 526 (7572): 187–189. doi: 10.1038/526187a
• Moncrieff, Joanna; Wessely, Simon; Hardy, Rebecca (2018). “Meta-analysis of trials comparing antidepressants with active placebos”. British Journal of Psychiatry . 172 (3): 227–231. doi: 10.1192/bjp.172.3.227
• Schulz, Kenneth F.; Grimes, David A. (2002). “Blinding in randomised trials: hiding who got what”. Lancet . 359 (9307): 696–700. doi: 10.1016/S0140-6736(02)07816-9

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• Dorothy Forbes
• Correspondence to : Dr Dorothy Forbes Faculty of Nursing, University of Alberta, Level 3, Edmonton Clinic Health Academy (ECHA), 11405-87 Ave, Edmonton, Alberta, Canada T6G 1C9; dorothy.forbes{at}ualberta.ca

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What is blinding?

Blinding (or masking) is the process used in experimental research by which study participants, persons caring for the participants, persons providing the intervention, data collectors and data analysts are kept unaware of group assignment (control vs intervention). Blinding aims to reduce the risk of bias that can be caused by an awareness of group assignment. With blinding, outcomes can be attributed to the intervention itself and not influenced by behaviour or assessment of outcomes that can result purely from knowledge of group allocation.

Why incorporate blinding?

Performance bias refers to systematic differences between the treatment and control groups resulting from care that was provided, or exposure to factors other than the interventions of interest. After enrolment into the study, blinding of participants and personnel may reduce the risk that knowledge of which intervention was received affects outcomes. If blinding is not incorporated or is unsuccessful, participants may respond better if they know they have received a promising new treatment. On the other hand, if participants are aware that they are not receiving an active treatment they may be less likely to comply with the study protocol, more likely to seek additional treatment and more likely to leave the study without providing outcome data. 5 The healthcare providers who are blinded to participant allocation are much less likely to transfer their values to participants or to provide differential treatment to the active and placebo groups. 5 However, blinding may not be possible in some studies where the intervention is obvious to the participants and/or persons administering the intervention (eg, an exercise intervention). Such studies can take other measures to reduce the risk of bias, such as treating participants according to a strict protocol to reduce the risk of differential behaviours by persons administering the intervention.

Blinding of outcome assessors is equally important to reduce the introduction of bias into the assessments and should be attempted whenever possible. 5 Outcome assessments may be made by the participants themselves, by their healthcare providers, or by independent assessors. Blinding of the statistical analysts is achievable by simply labelling the participants' data with non-identifying codes. 5

How to implement blinding?

Blinding is not a simple procedure. The researchers often need to engage a variety of approaches to enhance blinding. Boutron et al 6 conducted a systematic review of methods used in pharmacological RCTs to establish blinding of patients and/or healthcare providers. These included providing treatments in identical form, specific methods to mask characteristics of the treatments (eg, added flavour or colour), or use of double dummy procedures and even simulation of an injection.

Methods to avoid unblinding involved use of active placebo, centralised assessment of side effects, and patients informed only in part about the potential side effects of each treatment. Some of the methods used for blinding outcome assessors included centralised assessment of complementary investigations, clinical examination that involved the use of video, audiotape or photography, and adjudication of clinical events. Clearly there are ethical considerations to blinding. All blinding approaches should be explained as part of the method and receive ethical approval from research ethics boards.

How to assess if blinding has been successful?

An attempt to blind participants and personnel does not always ensure successful blinding in practice. For example, for many blinded drug trials, the side effects of the drugs can reveal group allocation, unless the study compares two rather similar interventions (eg, drugs with similar side effects, or uses an active placebo. 6 It has been suggested that it would be useful to ask trial participants at the end of the trial to guess which treatment they have received, 7 , 8 and some reviews of such reports have been published. 7 , 9 Evidence of correct guesses exceeding 50% would suggest that blinding may have been broken. However, responses may simply reflect the patients' experiences in the trial. A good outcome will tend to be more often attributed to an active treatment, and a poor outcome to a placebo. 10

Risk of bias may be high for some outcomes and low for others. For example, knowledge of the assigned intervention may impact on behavioural outcomes (eg, number of visits to their physicians), while not impacting on physiological outcomes or mortality. Thus, assessments of risk of bias resulting from lack of blinding may need to be made separately for different outcomes. Rather than assessing risk of bias for each outcome separately, it is often convenient to group outcomes with similar risks of bias. For example, there may be a common assessment for all subjective outcomes (eg, quality of life) that is different from objective outcomes (eg, blood work). 11

In summary, when considering the effectiveness of blinding in reducing the risk of bias, it is important to consider specifically:

Were the participants and study personnel blinded or not blinded?

Who assessed the outcomes and were they blinded or not blinded?

What was the risk of bias in the outcome assessment considering the subjectivity or objectivity of an outcome? 11

• Hróbjartsson A ,
• Jørgensen KJ ,
• Schulz KF ,
• Chalmers I ,
• Karanicolas PJ ,
• Farrokhyar F ,
• Boutron I ,
• Estellat C ,
• Guittet L ,
• Fergusson D ,
• Forfang E ,
• Higgins JPT ,

Competing interests None

Read the full text or download the PDF:

Psychologily

Double-Blind Studies: The Secret to Reliable Research Results

Double-blind studies are essential to research in various fields, including health and psychology. In a double-blind study, neither the participants nor the researchers know who receives a particular treatment. This procedure prevents bias in research results, which demand characteristics or the placebo effect can cause.

By withholding information about the treatment, double-blind studies help ensure that the results are as accurate and unbiased as possible. This method is beneficial when testing the efficacy of new medications or treatments. Without a double-blind study, researchers may unintentionally influence the results by giving more attention or care to one group over another.

Double-blind studies are also beneficial for preventing the placebo effect when a participant experiences an improvement in symptoms simply because they believe they are receiving treatment. The placebo effect is minimized by keeping both the participants and researchers in the dark about who is receiving the treatment. Overall, double-blind studies are a crucial tool for producing trustworthy and reliable research results.

Importance of Double-Blind Studies

When conducting research, minimizing potential biases that may influence the results is essential. One way to achieve this is by using double-blind studies. Double-blind studies are a type of research where neither the participants nor the researchers know who is receiving a particular treatment. This procedure is utilized to prevent bias in research results.

By using a double-blind study, we can minimize the effects of demand characteristics or the placebo effect. Demand characteristics are the cues that participants pick from the researcher, which may influence their behavior. The placebo effect is the phenomenon where a participant’s belief in a treatment’s effectiveness improves their condition, even if the treatment is not practical.

Double-blind studies are instrumental in the field of medicine. They are commonly used to test the efficacy of new drugs. By using a double-blind study, we can ensure that the results are not biased towards the drug being tested. This is important because if the results were biased, it could lead to the approval of an ineffective or harmful drug.

In addition to medicine, double-blind studies are also used in psychology research. For example, in a study on the effects of a new therapy, a double-blind study can ensure that the participant’s beliefs about the therapy do not influence the results.

Double-Blind Studies in Clinical Trials

Clinical trials are an essential part of medical research. They help researchers determine whether a new treatment is safe and effective. Double-blind studies are often used in clinical trials to prevent bias and maximize the validity of the research results.

Designing a Clinical Trial

In a clinical trial, participants are randomly assigned to either a treatment or control group. In a double-blind study, neither the participants nor the researchers know who receives the treatment and the placebo. This helps prevent bias in the results.

To design a double-blind study, researchers must carefully consider the study’s objectives, the population being studied, and the treatment being tested. They must also ensure that the investigation is conducted ethically and that all participants are fully informed about the study’s risks and benefits.

Analyzing Results

Researchers analyze the results after a double-blind clinical trial to determine whether the treatment is effective. They compare the outcomes of the treatment group and the control group to see if there is a significant difference between the two. If the treatment is effective, researchers may seek approval from regulatory agencies to make the treatment available to the public.

Analyzing the results of a double-blind study requires careful statistical analysis. Researchers must ensure that the study’s sample size is large enough to detect meaningful differences between the treatment and control groups. They must also control for any variables affecting the results, such as age, gender, or underlying health conditions.

Double-Blind Studies in Social Sciences

In social sciences, double-blind studies are commonly used to investigate the effects of various interventions, such as psychotherapy, medication, or lifestyle changes. Double-blind studies are instrumental in social sciences research because they help eliminate bias and increase the validity of the findings.

Methodology

In a double-blind study, neither the participants nor the researchers know who receives the treatment and the placebo. This helps eliminate the placebo effect and other biases affecting the study results.

To conduct a double-blind study, researchers must first recruit participants and randomly assign them to either the treatment or the control group. Then, the researchers must administer the treatment and the placebo in an identical way in appearance, taste, and smell. This ensures that the participants cannot tell whether they receive the treatment or the placebo.

During the study, the researchers must also ensure that they know the treatment assignment to the participants. For example, they may use coded labels or have a third party administer the treatment.

Interpreting Findings

When interpreting the findings of a double-blind study, it is vital to consider the limitations of the study design. For example, double-blind studies may only be feasible in some situations, such as when the treatment involves a surgical procedure or has obvious side effects.

It is also essential to consider the sample size and the characteristics of the study population. Double-blind studies may not be generalizable to all people, and the findings may not apply to individuals with certain conditions or factors.

Despite these limitations, double-blind studies remain essential in social sciences research. They help increase the validity of the findings and provide valuable insights into the effectiveness of various interventions.

Challenges in Double-Blind Studies

Double-blind studies are an essential methodological feature of clinical research studies that help maximize the validity of the research results. However, there are several challenges associated with conducting double-blind studies. In this section, we will discuss some of the most significant challenges that researchers face when conducting double-blind studies.

Limitations

One of the primary challenges of double-blind studies is the limitations associated with blinding. Blinding is a process that involves withholding information regarding treatment allocation from one or more participants in a clinical research study. However, blinding is only sometimes possible or practical. For example, in some studies, it may be impossible to blind the participants or the researchers due to the nature of the intervention or the study design.

Another limitation of double-blind studies is the potential for unblinding. Unblinding occurs when a participant or a researcher becomes aware of the treatment allocation. Unblinding can occur accidentally or intentionally and compromise the study results’ validity.

Ethical Considerations

Double-blind studies also raise ethical considerations. For example, in some studies, blinding may not be ethical if the intervention poses a significant risk to the participants. In such cases, the participants must be informed of the treatment allocation to ensure their safety.

Additionally, blinding can create ethical dilemmas for researchers. For example, researchers may be hesitant to withhold or deceive participants’ information. Moreover, researchers must ensure that the participants understand the risks and benefits of participating in the study and provide informed consent.

Conducting double-blind studies comes with several challenges, including limitations and ethical considerations. As researchers, we must be aware of these challenges and take steps to address them to ensure the validity and ethicality of our studies.

Future of Double-Blind Studies

As we move towards a more technologically advanced future, how we conduct double-blind studies is also evolving. This section will discuss some technological advancements and emerging trends shaping the future of double-blind studies.

Technological Advancements

One of the most significant technological advancements impacting double-blind studies is wearable devices. These devices can track physiological parameters such as heart rate, blood pressure, and sleep patterns, providing researchers with a wealth of data. This data can be used to monitor the effects of a particular treatment and determine if it is effective.

Another technological advancement that is gaining popularity is the use of mobile apps. These apps can collect data from study participants, making it easier for researchers to monitor their progress. For example, an app could remind participants to take their medication at a specific time, ensuring they adhere to the study protocol.

Emerging Trends

One of the emerging trends in double-blind studies is the use of virtual reality (VR) . VR technology can be used to create realistic environments that simulate real-world scenarios. This can be particularly useful in studies that involve phobias or anxiety disorders. For example, a VR environment could simulate a fear of flying, allowing researchers to study the effects of a particular treatment in a controlled environment.

Another emerging trend is using artificial intelligence (AI) in double-blind studies. AI can analyze large amounts of data quickly and accurately, making it easier for researchers to identify patterns and trends. For example, AI could analyze data from wearable devices, identifying specific physiological parameters affected by a particular treatment.

Frequently Asked Questions

How do double-blind studies work.

Double-blind studies are a type of research study in which neither the participants nor the experimenters know which group each participant has been assigned to. This type of blinding helps to prevent bias in research results. In a double-blind study, each subject’s group assignment is withheld from both the participant and the researcher performing the experiment. The assignment is hidden not only from participants and experimenters, but also from the researchers analyzing the data.

What is the purpose of conducting double-blind studies?

The purpose of conducting double-blind studies is to prevent bias in research results. By withholding the group assignment from both the participant and the researcher performing the experiment, researchers can ensure that the results of the study are not influenced by any preconceived notions or expectations of the participants or the researchers.

What are the advantages of using double-blind studies in research?

The advantages of using double-blind studies in research are numerous. By preventing bias in research results, researchers can ensure that the results of the study are more accurate and reliable. This can help to improve the quality of research and the validity of the conclusions drawn from the research.

What are the limitations of double-blind studies?

While double-blind studies are an effective way to prevent bias in research results, they do have some limitations. For example, double-blind studies may be more difficult to conduct than other types of studies. Additionally, double-blind studies may be more expensive and time-consuming than other types of studies.

How are double-blind studies different from single-blind studies?

In a single-blind study, only the participants are blinded to the group assignment. In a double-blind study, both participants and experimenters are blinded. This type of blinding helps to prevent bias in research results. Single-blinding occurs in many different kinds of studies, but double- and triple-blinding are mainly used in medical research.

What are some examples of successful double-blind studies?

There have been many successful double-blind studies conducted in various fields of research. For example, a double-blind study conducted in the field of medicine found that a certain medication was more effective than a placebo in treating a particular condition. Another double-blind study conducted in the field of psychology found that a certain type of therapy was more effective than another type of therapy in treating a particular mental health condition.

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• Published: 16 May 2019

Including the blind community in precision medicine research: findings from a national survey and recommendations

• Maya Sabatello LLB, PhD   ORCID: orcid.org/0000-0003-4444-5389 1 ,
• Lou Ann Blake JD 2 ,
• Audrey Chao BA   ORCID: orcid.org/0000-0003-4099-7004 3 ,
• Arielle Silverman PhD 4 ,
• Ronit Ovadia Mazzoni MS 5 ,
• Yuan Zhang MS, MA 6 ,
• Ying Chen MD, MS 7 &
• Paul S. Appelbaum MD   ORCID: orcid.org/0000-0002-1940-0042 8  

Genetics in Medicine volume  21 ,  pages 2631–2638 ( 2019 ) Cite this article

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Despite ongoing efforts to increase diversity of cohorts in precision medicine research (PMR), little is known about the obstacles to inclusion of blind people and those with low vision (“the blind community”) in PMR. The blind community comprises ~10% of the US adult population and its members commonly experience health disparities. Understanding barriers to inclusion of this community is necessary to facilitate their participation.

An online survey was developed in disability-accessible formats. Key questions included views on PMR; willingness to participate, provide data, and engage in the study; data sharing and consent; and perceived barriers to participation. Analyses describe results for all participants.

Two hundred seventy-one blind/low-vision participants completed the survey. Participants expressed strong support for PMR, and willingness to participate in PMR, to provide lifestyle, biological and medical information, to engage with the study, and to have their data shared with other researchers. Preferences for data sharing and consent models varied. Significantly, 65% identified 3–6 barriers to participation, particularly inaccessible transportation, clinics, and facilities; inaccessible information; and attitudinal and institutional barriers.

Removing the identified barriers is key. Measures that could increase inclusivity of blind people and those with low vision in PMR are suggested.

You have full access to this article via your institution.

INTRODUCTION

Precision medicine research (PMR) is an emerging approach for health care, aimed at developing prevention, diagnosis, and treatment options tailored to an individual’s genetics, environment, and lifestyle choices. PMR has gained momentum in the United States with the launch of the All of Us Research Program (AoU), which seeks to enroll, collect a range of data from, and engage with one million Americans. 1 Because the stakes of exclusion are high—communities underrepresented in PMR cohorts will not accrue the benefits of this research—the National Institutes of Health (NIH) have dedicated tremendous efforts to include historically marginalized racial and ethnic minorities in PMR. However, people with disabilities have not received much attention in planning PMR. This omission is concerning: as a group, people with disabilities experience significant health disparities. 2 Moreover, PMR initiatives that fail to address inclusion barriers in their early phases give the impression that certain populations are less valuable than others, with significant implications for whose interests will be considered in developing and implementing PMR studies. 3

Blind people and those with low vision (“the blind community”) are one subgroup of people with disabilities who could both benefit and are at risk of being excluded from PMR. Blindness and vision loss are among the most common adult medical conditions in the United States, 4 encompassing an estimated 21 million people (~10% of the adult population), 5 of whom ~2.8% are legally blind or have trouble seeing even with corrective lenses (“low vision”). 6 This population is projected to surge in the coming decades due to population aging and increased survival rates among people with chronic conditions that impact vision (e.g., diabetes). 7 Moreover, blind people have a higher rate of chronic conditions such as hypertension and heart conditions compared with sighted people. 8 Insofar as PMR could offer preventive and therapeutic opportunities for blind people, PMR inclusion will be key for them to reap the benefits.

The blind community’s views on biomedical research are understudied but raise unique issues. Medicine in general, including genetic research, has operated under a model that focuses on curing or ameliorating physical and other impairments, and tends to view life with disabilities as unsatisfying. Although these views have been contested by disability communities, including the blind community, 9 they have remained prevalent in society, and particularly in medical and research settings. 10 Most notoriously, the eugenics movement in the early 20th century in the United States (and elsewhere), with its focus on eliminating and preventing reproduction of those who were deemed “genetically unfit,” led to the forced sterilization of Americans with disabilities and later to mass euthanasia of people with disabilities in Nazi Germany. 11 This history may evoke concerns that the genomic component of PMR will replicate historical wrongs.

Conversely, studies of patients with inherited vision conditions found support for diagnostic and predictive genetic testing. The strongest motivating factors were the possibility of identifying a novel treatment, understanding the cause of their visual disability, and confirming the inheritance of their condition, though most stated that they would not support pregnancy termination on this basis. 12 , 13 Support for genetic research similarly can be found in NIH’s eyeGENE® initiative, a repository for DNA that includes >6400 records of patients with rare inherited eye diseases ( https://eyegene.nih.gov/ ). While informative, there are several reasons why these findings may not completely apply to PMR. First, PMR’s exploratory goals do not necessarily focus on particular impairments, and thus require willingness to participate in scientific research that may not yield a diagnosis or intervention for one’s own condition. Second, PMR requires not only one-time biospecimen collection but also other environmental and lifestyle information, thus raising concerns about privacy. Third, successful PMR requires long-term engagement—and thus also more time investment—by research participants.

We report findings from a national survey exploring the views of the blind community about participation and barriers to participation in PMR. This is a part of a larger study that included people with various disabilities ( n  = 1294). By focusing on blind/low-vision people, this article seeks to highlight the views and concerns of this group, and to offer tailored suggestions for developing PMR that is inclusive of the blind community.

MATERIALS AND METHODS

Study design, procedures, and survey.

The methods and data collected for this study are detailed elsewhere. 14 In brief, we conducted a national, Internet-based survey of people with disabilities to explore their views on PMR. The survey described a hypothetical national PMR cohort study (Appendix A ), including information about PMR, key terms (e.g., genetics), and what participation in PMR might entail (e.g., data collection, access to their health information). Survey questions probed participants’ views about PMR; most relevant for this paper are whether PMR should be conducted, and respondents’ willingness to participate, to provide various types of data, and to engage in specific aspects of the study, along with their views about data sharing and consent, and perceived barriers to participation. Demographic data were collected. Most questions had dichotomized (yes/no) or predefined response options; questions about barriers to participation included an open-ended option.

The study was conducted in collaboration with several national organizations of persons with disabilities: the National Federation of the Blind (NFB), the Association of University Centers on Disabilities (AUCD), the National Council on Independent Living (NCIL), the National Association of the Deaf (NAD), and the American Association of Health and Disability (AAHD). People with disabilities, including blind people, were consulted about the survey’s wording and accessible format and programming to ensure that the survey could be “read” by screen readers (or text-to-read programs). The national organizations circulated the invitation and a link to participate in the study through their listservs. Given this recruitment method, it was impossible to assess response rate. The survey was available in English, Spanish, and American Sign Language  (as translated by the NAD), hosted by SurveyMonkey, and estimated to take 17 minutes to complete. Participants were offered a $25 gift card. The institutional review board (IRB) at the New York State Psychiatric Institute approved the study.

For this paper, eligibility criteria for the primary study population were being at least 18 years old and identifying as blind or having low vision as a primary disability. Participants provided consent online and were required to answer correctly two questions about the study’s purpose to access the survey.

Statistical analysis

All statistical analyses were performed with SAS 9.4 software. Demographic characteristics were reported as counts and percentages. Chi-square (χ 2 ) tests were used for categorical variables to compare differences among groups. Linear regression was conducted for total number of barriers (a continuous variable). Covariates were collapsed and recoded when data cells were small to reduce the number of categories for analysis.

Study population

Of the 1294 participants with disabilities in the study, 271 identified as blind or with low vision as a primary condition, including 30% who reported multiple disabilities (e.g., autism, physical disabilities); 52.7% were female, 45.2% male, and 2.1% identified as nonbinary sex. Most participants were White (80%) and employed full or part time (58%). A minority completed high school/GED or less (15%). Only 14% reported <$20,000 household income (national poverty line is <$24,000/family of four 15 ). The demographic characteristics of survey respondents are presented in Table  1 .

PMR and willingness to participate

Ninety-eight percent of blind/low-vision participants supported conducting the PMR study described in the survey, of whom 90% said that they would participate if asked; 63% would be willing to participate for 5–10 years, and 19% for their lifetimes. Overall, 96% agreed that “[t]he study could lead to better treatments, cures, and save lives.” No differences were observed across racial, ethnic, and gender groups. Compared with participants with other disabilities, support for conducting the study and belief in its therapeutic promise were higher among blind participants (respectively: 98% vs. 95%, p  = 0.0345; 96% vs. 89%, p  = 0.0007).

Data provision

Participants were asked to select from eight types of data that they would agree to provide, if they participated in the study. Most were willing to provide lifestyle information such as diet and exercise (78% vs. 65% compared with participants with other disabilities; p  < 0.0001); samples like urine, saliva, or hair (76% vs. 72%; p  = 0.1131); a blood sample (73% vs. 73%); genetic data (69% vs. 61%; p  = 0.0131); samples of the soil or water around their home (“environmental samples”) (64% vs. 47%; p  < 0.0001); and family history (63% vs. 58%; p  = 0.1338). Fewer blind/low-vision participants were willing to provide heart rate or daily number of steps from their Fitbit or smartphone (46% vs. 31%; p  < 0.0001) and information from their social media accounts (28% vs. 35%; p  = 0.0312).

Data sharing and consent

Seventy-seven percent of blind/low-vision participants agreed with the statement that “[i]f my name and contact information are removed, data and research results from my samples can be made available for anyone to use.” However, consent for researchers’ use of participants’ data varied (“models of consent”). The largest fraction agreed that “researchers can use [my] data in all types of research studies, but only if [I am] able to see in which studies the data will be used and decide not to participate” (31%), followed by use of participants’ data “in all types of research studies” (25%), “only if [I] give specific permission for each study” (23%), and “only for the research study [I] choose when [I] enroll” (21%).

When asked which types of researchers they would allow to use their samples and information, most blind/low-vision participants selected NIH researchers (78%) and university researchers in the United States (66%). Only a minority selected “other government researchers” (35%), “university researchers in other countries” (29%), and “researchers from commercial companies that develop drugs” (26%).

Responses to engagement questions, including comparisons with other study participants, are shown in Table  2 . The overwhelming majority of our blind participants agreed that “research participants and researchers [should] be equal partners” (82%), and most also said they would be more willing to participate “if participants helped to plan and run the study” (66%). Engagement in determining study priorities was most important to blind participants: 62% wanted to “help choose research questions” (more than other study participants [53%]; p  = 0.0088), followed by “help decide what kinds of research are conducted” (44%). blind/low-vision participants were also more likely to want to “help decide what to do with study results” (37% vs. 21%; p  < 0.0001).

Barriers to participation

Participants were asked to “select all that apply” from a list of barriers that “may stop you from participating in the study” (Table  3 ). Responses most frequently endorsed by blind/low-vision participants were “transportation to health-care facilities is difficult” (55%), “the space and equipment in clinics and health-care facilities are not accessible for me” (50%), “information about medical research is not accessible to me” (43%), “my health insurance may not cover the costs” (39%), and “transportation to health-care facilities is too expensive” (38%). About a third of blind/low-vision participants indicated that researchers and health-care providers “have stereotypes about people with disabilities” (36%; higher than other participants: 23%, p  = 0.0003) and “lack knowledge of my needs” (30%). Fewer endorsed concerns that “research may be used for studies I don’t approve of” (26%), their medical problems could impede participation (23%), or PMR “might be used to harm people like me” (25%) and will increase stigma (10%). Although some barriers were experienced similar to (e.g., transportation) or less than (e.g., communication difficulties) other study participants, the total number of barriers selected by blind/low-vision participants was high: 15% reported 1–2 barriers (24.7%) and 65% identified 3–6 barriers.

PMR studies increasingly are seeking to engage diverse communities, for which including blind/low-vision people and others with disabilities will be key. The success of this effort will depend on the views of blind people about PMR and the removal of obstacles to their engagement. Our findings suggest high levels of interest in PMR but also many concerns about barriers to participation.

Blind participants—more than other study participants—overwhelmingly supported PMR. They expressed strong belief in its potential therapeutic benefits and were highly interested in extended participation. Notably, this enthusiasm for PMR is substantially higher than the already-high positive responses found in a previous survey of the general US adult population. 16 A majority of our blind participants further indicated willingness—often more than other study participants—to provide the three key data types needed for PMR: medical and biological information (i.e., family history, genetic data, biological samples), environmental samples, and lifestyle information, though they were reluctant to provide data that are more time-consuming to report or that evoke concerns over excessive surveillance, i.e., exercise data from Fitbits or smartphones and data from social media accounts.

Most of our blind/low-vision participants would provide broad consent for uses of their data (including those who conditioned consent on the option to opt out) and data sharing with NIH and university researchers. This willingness may be reassuring for national and university-based PMR programs. However, almost a quarter of participants wanted to provide consent for data use on a study-by-study basis, and most participants expressed reluctance to share data with other entities. Indeed, a majority of participants were not willing to share their data with other government researchers (65%), university researchers in other countries (71%) and, in particular, researchers with pharmaceutical companies (74%). While the vagueness of “other government researchers” may partially explain this finding (e.g., would it include law enforcement?), the reluctance to share data with foreign and commercial researchers requires further exploration. Suspicion of pharmaceutical companies may arise from practices such as exorbitant drug pricing and from failures specific to the blind community, such as inaccessible labeling (without braille or large print). 17 This reluctance may raise challenges for the extensive public–private collaborations that PMR initiatives often require. Measures to address this may include creating processes to share the financial benefits of product development and greater attention to the specific needs of the blind community.

Notwithstanding the overall excitement about PMR among members of the blind/low-vision community, participants also identified multiple barriers to participation that, if unaddressed, will likely limit enrollment. These barriers largely mirror ones previously identified as key for blind/low-vision people (and other people with disabilities) in health-care settings: 18 , 19 , 20 inaccessible transportation, 18 , 21 information, 17 , 22 and physical facilities, 23 along with stereotypes among physicians and office staff and lack of training and awareness on working with blind individuals. 20 The impact of other concerns on participation in PMR (i.e., unapproved studies, harm, and stigma) is unclear. Similar concerns about promoting eugenics and other group harms were raised in studies of racial/ethnic minorities, though direct comparisons are complicated by inconsistent findings and differences in framing of questions about harms and study context (i.e., PMR vs. genetic testing/biobanking). 24 , 25 Further exploration of the basis for concerns about PMR leading to eugenic efforts or other group harms, especially among blind people from racial/ethnic minorities (too few in our sample), is merited.

Still, the combination of barriers cited is worrisome, first, because of their high prevalence, and second, because our respondents overall were more educated and wealthier than the average blind person in the United States (45% of our participants had bachelor's or graduate degrees, compared with 16% among the general blind/low-vision population; 42% reported household income of >$56,000, compared with a median of $41,000 for adults with visual disability). 15 Less educated and poorer individuals will likely face even more barriers to participation. A systematic approach to address the many barriers is clearly needed for the full inclusion of blind people in PMR.

Designing inclusive PMR studies not only benefits the field by increasing the diversity of study cohorts but ensures compliance with US law. The Americans with Disabilities Act (ADA) forbids discrimination on the basis of disability in public life, which includes ensuring accessibility, and applies to both government entities and private places of public accommodation, including universities and hospitals. 26 Research initiatives run at these facilities, including private–public partnerships, are thus subject to ADA requirements. Additionally, Section 504 of the Rehabilitation Act forbids discrimination on the basis of disability in any organization that receives federal financial assistance, a category that covers most entities conducting PMR. Thus, measures that could increase inclusivity of the blind/low-vision community in PMR include addressing the following barriers:

Inaccessible transportation , defined as not being able to reach the intended destination, when needed, in a reasonable amount of time. 21 It encompasses unaffordable transportation, limited public transportation during off-hours (i.e., nights and weekends), and paratransit services that operate on rigid schedules, increasing the risk that blind participants will be stranded if an appointment runs late. 20 , 21 Accordingly, scheduling research visits on weekends or after work may not be particularly effective for increasing research participation among blind participants. Instead, researchers can consider offering free transportation to and from research sites (including, e.g., providing transportation vouchers for taxis and/or ride-sharing reimbursement), assisting participants in identifying public transit routes to the facility, and developing more local, community-based centers for enrollment and data collection that allow potential participants to avoid travel.

Inaccessible clinics and facilities . Blind individuals face numerous barriers at health-care facilities. These include lack of sidewalks leading directly to the clinic; 23 facilities without public transit stops in front of the building, requiring blind people to pass through parking lots or other buildings to enter the facility; 23 and facilities with multiple entrances, making coordination with paratransit services difficult. 27 Once inside the facility, spaces that lack braille or large print signs for identification and information about how to navigate through the facility constitute additional barriers. 19 Given these barriers, it is unsurprising that 50% of our blind/low-vision participants stated that clinics and health-care facilities themselves are not accessible. Increasing accessibility to clinics and research facilities requires fairly simple adjustments: PMR staff can provide blind participants with braille or audio descriptions of the facility space and/or arrange for study personnel to meet blind participants in an identifiable location, accompany them to the facility, and assist them with enrollment and collection of data and samples. Access to technologies that offer visual interpreter services (e.g., Be My Eyes) may similarly increase mobility independence for blind participants, though these services cannot always substitute for a human guide in unfamiliar places and may be challenging for less technologically literate participants.

Inaccessible information . Almost half of our blind/low-vision respondents (43%) stated that information about medical research is not accessible to them. This finding is in line with other studies indicating that medical and research information is often unavailable in braille or audio formats. 20 , 22 This situation is further exacerbated by health-care facilities increasingly replacing in-person communication with technology, for instance, the use of touchscreen, check-in kiosks for patient registration and to obtain and communicate information. 28 Such technologies are assumed to save time and cost 29 and graphical interfaces have gained popularity due to their visual appeal 30 . However, they are infrequently designed in consultation with blind users, making many of their graphical elements and dynamic web content inaccessible 31 .

These technological challenges further extend to home computer systems modified for use by blind persons. Because websites and survey interfaces tend to utilize different operating systems and screen readers, they can often be incompatible with privately owned screen readers. 32 Blind individuals thus must switch from their known screen reader at home to other screen-reading programs, a process that may not be easy to navigate and that requires them to learn a new program. This challenge is further complicated because screen reader programs may work better with some browser options (e.g., Firefox) than with others. 32 The use of such technologies is likely to have significant impact on the participation of blind people in PMR. PMR initiatives increasingly utilize computer-based technologies to disseminate information, obtain online consent, enroll participants into PMR cohorts, and enable ongoing engagement and return of results. Without concrete measures to rectify the identified technological barriers, online PMR recruitment and communication efforts will likely be inaccessible to many blind people, discouraging them from even trying to engage in research 33 .

PMR studies can take several steps to reduce these challenges. These include installing screen reader technologies on relevant public devices, including cross-modal output that uses audio or haptic cues to communicate three-dimensional images to blind participants 30 and providing earphones for privacy; designing user interfaces that are structured in a blind-accessible way (e.g., an entirely text-based linear layout without graphics that can be read by screen readers), 30 including adherence to the recommendations made by the World Wide Web Consortium for ensuring web content accessibility; 34 and supplying blind participants with a tablet with screen reader software for their use, which would allow for long-term engagement in studies.

Attitudinal and institutional barriers . A large minority of our blind respondents expressed concerns that researchers held stereotypes about people with disabilities (36%) and that researchers lacked knowledge of their needs (30%). These responses are unsurprising given previous research on how unpleasant health-care experiences can be for blind individuals. 20 , 35 Educating health professionals and researchers about the blind community and encouraging professionals’ self-reflection on their own biases about blind people would be a first step. Thus, it is key for PMR personnel to be aware of privacy concerns, especially given participants’ visual disabilities; to ask for individuals' preferences about how to be assisted in navigating space and technologies (e.g., receiving verbal directions, led audibly, or led by physical touch); 20 and to work with blind experts to ensure that PMR is accessible for blind users. Developing a protocol for engagement and working with blind people as equal partners can facilitate rapport-building, and research institutions should require that such processes are in place. Indeed, such steps embody a core pillar of PMR—i.e., community engagement—and shift the historical view of people with disabilities, including blind people, primarily as subjects of study to partners and experts on their own conditions.

Increasing engagement . blind/low-vision participants in our study expressed high enthusiasm for serving as active and equal partners in PMR-related decisions, especially determining research priorities. Two-thirds of respondents said that they would be more willing to participate “if participants helped to plan and run the study.” The blind community is ripe for engagement. Through collaboration with blind participants and organizations that represent them, remedies for barriers to inclusion can be implemented. As with other historically marginalized communities, involvement of blind participants will be key for identifying and conducting PMR that is responsive to the needs of the community.

This study has several limitations, primarily the small sample of blind/low-vision participants from racial/ethnic minorities who may have other concerns that would discourage their participation in PMR (similar to members of such communities more generally 36 , 37 , 38 ). Our participants also had higher education, employment rates, and household incomes than the average blind/low-vision population in the United States. 15 Although underrepresentation of participants with lower socioeconomic status is common in medical studies, 16 it may have skewed the results to be more supportive of PMR. For example, higher education has been found to correlate with greater interest and willingness to participate in PMR; 39 however, no such correlation was found in this study. Finally, our method of recruitment—an online survey, circulated through listservs of organizations of people with disabilities—is likely to have excluded blind (and other) participants who do not have access to the Internet or who are not involved with such organizations. Future research should focus more specifically on the racial, ethnic, socioeconomic, and other groups that were not sufficiently included in this study.

Our study is nonetheless highly informative for PMR. It explores the views of a previously unstudied population—i.e., blind people and people with low vision—on PMR. The challenges of inaccessible transportation, information, and facilities, as well as the other attitudinal, institutional, and economic barriers identified in this study are likely to be relevant for members of the blind community across racial, ethnic, and socioeconomic groups, for whom health disparities and accessibility issues are often compounded. 40 Besides highlighting the need to remove these barriers to inclusive PMR, our findings demonstrate the interest of the blind community in involvement and engagement as equal partners in PMR-related decisions. If PMR is indeed to provide the future health-care model for the United States, researchers must ensure that historically underrepresented communities with disabilities are included and thus able to reap the potential benefits. Learning about the views of these communities is the first step toward implementing inclusive practices and developing long-term relationships and engagement opportunities.

National Institutes of Health. All of Us Research Program. 2018. https://allofus.nih.gov/ .

Krahn GL, Walker DK, Correa-De-Araujo RM. Persons with disabilities as an unrecognized health disparity Population. Am J Public Health. 2015;105(S2):S198–S206.

Article   Google Scholar  

Sabatello M, Appelbaum PS. The precision medicine nation. Hastings Center Report. 2017;47:19–29.

Courtney-Long EA, Carroll DD, Zhang QC, Stevens AC, Griffin- Blake S, et. al. Prevalence of Disability and Disability Type Among Adults—United States. 2013:64;777–783.

National Center for Health Statistics. Table A-6a: Age-adjusted percentages (with standard errors) of hearing trouble, vision trouble, and absence of teeth among adults aged 18 and over, by selected characteristics: United States, 2017, in Summary Health Statistics. 2017. Centers for Disease Control and Prevention. https://ftp.cdc.gov/pub/Health_Statistics/NCHS/NHIS/SHS/2017_SHS_Table_A-6.pdf . Accessed 10 May 2019.

American Foundation for the Blind. Research Navigator: Just how many blind folks are there anyway? https://www.afb.org/newsletters/directconnect-newsletter/research-navigator-just-how-many-blind-folks-are-there-anyway . Accessed 10 May 2019.

Centers for Disease Control and Prevention. Vision health initiative: projection studies. 2017. https://www.cdc.gov/visionhealth/projects/projection-studies.html . Accessed 10 May 2019.

Crews JE, Chou CF, Sekar S, Saaddine JB. The prevalence of chronic conditions and poor health among people with and without vision impairment, aged ≥65 years, 2010–2014. Am J Ophthalmol. 2017;182:18–30.

Maurer M. Jacobus tenBroek Law Symposium keynote address. Texas J Civ Liberties Civ Rights. 2008;13:157–166.

Google Scholar  

Williams G. Theorizing disability. In: Albrecht GL, Seelman K, Bury M, eds. Handbook of disability studies. Thousand Oaks, CA: SAGE Publications; 2001. p. 123–144.

Braddock DL, Parish SL. An institutional history of disability. In: Albrecht GL, Seelman K, Bury M, eds. Handbook of disability studies. Thousand Oaks, CA: SAGE Publications; 2001. p. 11–68.

Bong C, Potrata B, Hewison J, McKibbin M. Attitudes of patients and relatives/carers towards genetic testing for inherited retinal disease. Eye. 2010;24:1622–1625.

Article   CAS   Google Scholar  

Mezer E, Babul-Hirji R, Wise R, et al. Attitudes regarding predictive testing for retinitis pigmentosa. Ophthalmic Genet. 2007;28:9–15.

Sabatello M, Chen Y, Zhang Y, Appelbaum PS. Disability inclusion in precision medicine research: a first national survey. Genet Med. 2019 Mar 22; https://doi.org/10.1038/s41436-019-0486-1 [Epub ahead of print].

Lisa Yang K, Hock E. Tan Institute on Employment and Disability Collection. Disability statistics. 2016. https://digitalcommons.ilr.cornell.edu/edicollect/ . Accessed 10 May 2019.

Kaufman DJ, Baker R, Milner LC, et al. A survey of U.S. adults’ opinions about conduct of a nationwide Precision Medicine Initiative® Cohort Study of genes and environment. PLoS One. 2016;11:e0160461.

Equal Rights Center. Ill-prepared: health care’s barriers for people with disabilities. 2011. http://www.tilrc.org/assests/news/publications/erc_ill-prepared_report_11-11.pdf . Accessed 10 May 2019.

Crudden A, McDonnall MC, Hierholzer A. Transportation: an electronic survey of persons who are blind or have low vision. J Vis Impair Blind. 2015;109:445.

Story MF, Schwier E, Kailes JI. Perspectives of patients with disabilities on the accessibility of medical equipment: examination tables, imaging equipment, medical chairs, and weight scales. Disabil Health J. 2009;2:169–179 e1.

O'Day BL, Killeen M, Iezzoni LI. Improving health care experiences of persons who are blind or have low vision: suggestions from focus groups. Am J Med Qual. 2004;19:193–200.

Bezyak JL, Sabella SA, Gattis RH. Public transportation: an investigation of barriers for people with disabilities. J Disabil Policy Stud. 2017;28:52–60.

Thurston M, Thurston A. Risks to client confidentiality when communicating health information to blind and partially sighted persons. Disabil CBR Incl Dev. 2013;24:22–40.

Crudden A. Transportation issues: Perspectives of orientation and mobility providers. J Vis Impair Blind. 2015;109:457–468.

Laskey SL, Williams J, Pierre-Louis J, et al. Attitudes of African American premedical students toward genetic testing and screening. Genet Med. 2003;5:49–54.

Thompson HS, Valdimarsdottir HB, Jandorf L, Redd W. Perceived disadvantages and concerns about abuses of genetic testing for cancer risk: differences across African American, Latina and Caucasian women. Patient Educ Couns. 2003;51:217–227.

Americans with Disabilities Act of 1990. 42 U.S. Code § 12101.

Sharts-Hopko NC, Smeltzer S, Ott BB, et al. Healthcare experiences of women with visual impairment. Clin Nurse Spec. 2010;24:149–153.

Jones R. The role of health kiosks in 2009: literature and informant review. Int J Environ Res Public Health. 2009;6:1818–1855.

Yvonne Chan Y-F, Nagurka R, Bentley S, et al. Medical utilization of kiosks in the delivery of patient education: a systematic review. Health Promot Perspect. 2014;4:1–8.

PubMed   PubMed Central   Google Scholar  

Leuthold S, Bargas-Avila JA, Opwis K. Beyond web content accessibility guidelines: design of enhanced text user interfaces for blind internet users. Int J Hum Comput Stud. 2008;66:257–270.

Gottliebson D, Layton N, Wilson E. Comparative effectiveness report: online survey tools. Disabil Rehabil Assist Technol. 2010;5:401–410.

Billah SM, Ashok V, Porter DE, Ramakrishnan IV. Ubiquitous accessibility for people with visual impairments: are we there yet? Proc SIGCHI Conf Hum Factor Comput Syst. 2017;2017:5862–5868.

Sabatello M. Precision medicine, health disparities, and ethics: the case for disability inclusion. Genet Med. 2018;20:397–399.

Accessibility Guidelines Working Group. Web content accessibility guidelines (WCAG) 2.1. 2018. http://www.w3.org/TR/WCAG21/ . Accessed 10 May 2019.

Iezzoni LI, Davis RB, Soukup J, O’Day B. Quality dimensions that most concern people with physical and sensory disabilities. Arch Intern Med. 2003;163:2085–2092.

Kerasidou A. Trust me, I’m a researcher!: the role of trust in biomedical research. Med Health Care Philos. 2017;20:43–50.

Bentley AR, Callier S, Rotimi CN. Diversity and inclusion in genomic research: why the uneven progress? J Community Genet. 2017;8:255–266.

Halbert CH, McDonald J, Vadaparampil S, et al. Conducting precision medicine research with African Americans. PLoS One. 2016;11:e0154850.

Kaufman D, Murphy J, Scott J, Hudson K. Subjects matter: a survey of public opinions about a large genetic cohort study. Genet Med. 2008;10:831–839.

Yee S, Breslin M-L, Goode TD, et al., Compounded disparities: health equity at the intersection of disability, race, and ethnicity. 2018. The National Academies of Sciences, Engineering, and Medicine. http://nationalacademies.org/hmd/~/media/Files/Activity%20Files/SelectPops/HealthDisparities/Commissioned%20Papers%20and%20Perspectives/Compounded%20Disparities%20-%20Intersection%20of%20Disabilities%20Race%20and%20Ethnicity.pdf . Accessed 10 May 2019.

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Acknowledgements

This work was supported by National Human Genome Research Institute (NHGRI) grant K01HG008653, NHGRI/All of Us Research Program grant 3P50HG007257-05S1, and NIH Office of the Director (OD). We gratefully acknowledge the support of the Association of University Centers on Disabilities (AUCD), the National Council on Independent Living (NCIL), National Federation of the Blind (NFB), the National Association of the Deaf (NAD), and the American Association of Health and Disability (AAHD), which assisted with recruitment, survey material, and programming. We also gratefully acknowledge the support of individuals who assisted in this process: Howard A. Rosenblum, Lizzie Sorkin, Abiodun Ramroop, Dawn Rudolph, Kelly Buckland, Cara Liebowitz, Mark Starford, Marcia Orland, Kecia Brooke Weller, Charlene Jones, Roberta Carlin, Kathy Guernsey, Carlos Ríos Espinosa, Anthony Stephens (American Council of the Blind), Amar D. Mandavia, and Dave Kaufman. Finally, we thank the numerous individuals who took the time to participate in our study.

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Sabatello, M., Blake, L.A., Chao, A. et al. Including the blind community in precision medicine research: findings from a national survey and recommendations. Genet Med 21 , 2631–2638 (2019). https://doi.org/10.1038/s41436-019-0533-y

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• Double Blind Studies in Research: Types, Pros & Cons

In the medical field, it is unethical to not inform your patient of a process or a procedure you want to carry out on them. It is required that the patients are informed about the treatment they would be given and that they consent to it. 

However, there is a method known as the blind study in psychological research.  A blind study prevents the participants from knowing about their treatment to avoid bias in the research.

This article will focus on the double-blind study which is a type of blind study which leaves both the researcher and the participants in the dark about important details of the study . That way the research is expected to be bias-free and far from any external influence.

The blind study has no ground in patient-doctor physical therapy sessions, but it is very helpful in other studies such as pharmacological research.

This is why we will consider a double-blind study, its usefulness, advantages, and disadvantages in a study or research. 

What is a Blinded Study?

A blinded study is research conducted in a way that prevents the subjects ( blind the subjects) from knowing the treatment they are given so that the researcher is guaranteed a biased free result. Information that can influence the subjects of a research is withheld from the subjects until the completion of the research.

If good blinding is carried out on the subjects, it can eliminate any form of biases that may arise from the subjects’ expectations, influence from the researcher, researcher’s bias , and other forms of biases that may occur in a research test.

This can be achieved as a blind study can be imposed on all participants in research. From the researcher to the subjects, the analysts, and even the judges or evaluators.

Free to use: Participant Consent Form Template

In some cases, however, imposing blind study in research may be impossible or even unethical. For example, it is unethical for a medical practitioner to blind a patient from knowing their treatment. The ethical thing to do is let your patient be informed about a major part of their treatment if it’s in a face-to-face intervention.

A subject can become unblinded during a study if they obtain information that has been previously shielded away from them. For example, if due to experiencing some side effects symptoms, a subject could correctly guess the treatment he/she has been exposed to. The subject then becomes unblinded. Subjects becoming unblinded mostly occur in pharmacological testings. 

Use for free: Telemedicine Patient Evaluation Form

What is a Double-blind Study?

Double-blind refers to a study or research where both the subjects or participants of a study and the researchers are oblivious of the treatment being given and the subjects receiving the treatment. Both the participants and the experimenter are kept in the dark. This is done to eliminate all presence of biases in the outcome of the research.

It is most useful in research because of the placebo effect.

For example, if a researcher wants to conduct research on the effects of a newly introduced drug . A double-blind study requires that both the researcher and the subjects are unaware of the process.

So the researcher that is analyzing the subjects would have no information about the subjects receiving the new drug (which is the treatment group) and those who are not receiving the drug (which is the control group).

Now if the participants are not aware of their treatment and the researcher is not provided with information on who is receiving the treatment, the question that requires an answer is, why is a double-blind study needed?

Explore: 21 Chrome Extensions for Academic Researchers in 2021

Purpose of a Double-blinded Study

Every procedure has its purpose and a double-blind study is not left out. The purpose of a double-blind study is to make sure that the outcomes of a study are free from biases. Using the double-blind method in a study improves the level of credibility and validity of the study 

A double-blind study is used in the scientific field, psychologists, and also in the legal process.

Read more: What are Cross-Sectional Studies: Examples, Definition, Types

Types of Blinded Studies

There are three types of blind studies namely single-blind study, double-blind study, and triple-blind study

1. Single-blind study : in this type of blind study only the subjects in the experiment are prevented from knowing the treatment they are given. The single-blind study is also known as the single masked study.

2. Double-blind study:   In the double-blind study both the subjects or participants and the researcher are blinded.  The researcher is unaware of who is receiving what treatment and the participants are unaware of the treatment they are receiving.

3. Triple blind study : here in the triple-blind study the participants, the researcher analyzing data , and the data collector are blinded from the information about the study. These three groups are prevented from knowing the treatments being given out or being received.

When to Use Each Type of Blind Study

Now that we know the types of blind study we are going to consider when it is appropriate to use either of these types of blind study in research.

• When to use a single-blind study

A single-blind study is usually conducted to prevent the subject from being aware of the treatment being studied. This is in case they get influenced and that leads to bias in the outcome.

It should be noted that there are cases where blinding a participant or patient is considered unethical. Therefore, single-blind study should only be used in statistical research or studies that don’t involve physical therapy between a patient and a doctor.

• When to use a double-blind study

Double-blind study is conducted when both the participants and the researcher are not allowed to know details of the research. This process is used to prevent bias in the study results and when there is a need to understand the characteristics of the results or to understand placebo effect.

• When to use a triple-blind study :

Use triple blind study if you aim to reduce your study and improve the accuracy of your results. This is because a triple-blind study allows randomization where the treatment item and the intervention are not known to the participants, researcher, data collector , or clinical personnel.

Read: Survey Errors To Avoid: Types, Sources, Examples, Mitigation

Advantages of Double-blinded Study

The following are the advantages of double-blind study:

1. It tests for three groups

The double-blind study usually involves three groups of subjects. The first is the treatment group, then the placebo, and lastly, the control group. The treatment group and the placebo are given the test item even though the researcher wouldn’t know which group is getting the treatment. No test item is administered to the control group because they are used as a basis of comparison for the results of the treatment group and the placebo.

If there’s a significant improvement in the placebo group over the control group, then it is considered that the treatment administered worked.

2. Reduces experimental bias

A double-blind study reduces the risk of biases in research. Biases can occur when a researcher influences the outcome of a study directly or otherwise. However, because the researcher is often also in the dark, it is difficult to influence the study.

This allows for credible, reliable, and valid research results.

3. Result duplication

The results of a double-blind study can be duplicated and that is why this procedure is considered one of the best practices. A double-blind study allows other researchers to follow up with the same processes, apply the test item, and compare the result with the control group.

The usefulness of this method is that if the results from these studies are close, it proves the validity of the test item that was administered. If there is no duplication in the research results, another study has to be carried out to determine why.

Disadvantages of a Double-Blind Study

1. it is expensive.

One huge disadvantage of a double-blind study is that it is expensive to conduct. It takes several months or years to complete because the researcher has to examine all the possible variables and they may have to use different groups to gather enough data. 

Many corporations after estimating the cost of this study which runs into millions of Dollars might have to spread the research across multiple months. Even for government studies, conducting this study may run into billions of dollars thereby making the medicine expensive in the market. This is one of the reasons why new prescription medicines are sold at an expensive price in the market.

2. Low representation

A double-blind study cannot provide a properly represented sample group because it is small. Most double-blind study is designed to enroll at least 100 people or participants for the research however the most preferable number is 300. It is true that the effectiveness of a treatment can be proven even in small studies but more people or participants are required to determine a pattern in research so that the results can be properly analyzed and verified.

Research generally requires participants in large numbers to participate in the trials and progress of a treatment being administered or in plan to be introduced to the market.

This is because even when the product or treatment item has gotten to the third phase of testing it still has only a 60% chance to proceed to another stage.

3. Negative reaction

In some cases some of the participants may react negatively to the treatment item when this happens the results from the test can be compared to see what changed. Some participants may react negatively to the placebo which may lead to producing some side effects that may make it seem like they were receiving the treatment item when they did not.

4. Time factor

Many times it is almost impossible to complete a double-blind study. For example, you cannot keep the subject or participants of a psychotherapy experiment in the dark about who gets the treatment item and who doesn’t get the treatment item. Double-blind study can only work in this scenario if you find a way to provide two similar procedures without each of the groups communicating about which group is getting the treatment item and which group is getting the placebo.

Frequently Asked Questions about Blind Studies

• Which is better: single-blind or double-blind study?

To determine which is best between a single-blind study and a double-blind study the case being studied has to be considered.

For example, if a researcher is conducting a study on the effects of a medicine that can cure Alzheimer’s, it is best to use a double-blind study rather than a single-blind study. This is because the participants will be unaware if they received the treatment item from the real drug or if they received the placebo which in turn reduces any external influence on the results of the test.

• When would you use a single-blind study?

Use a single-blind study if the participants having knowledge of the group they belong to might result in bias. I.e. whether their being aware of the treatment item and the questions of the study might result in bias.

• What is the difference between a single and double-blind study?

The significant difference between a single study and a double-blind study is that in a single-blind study only the participants or the patient are blinded while in a double-blind study both the participant and the researcher are blinded.

In any study, it is good to know how the results of the treatment group and the response group compare in an experiment. This is why a double-blind study is important. 

The risk of anyone manipulating data or influencing the participants is averted since a double-blind study prevents both the researcher or the participants from obtaining in-depth knowledge of the study.

You can be assured that the researcher cannot accidentally communicate with the subjects or participants. Now that is one huge importance and psychological benefit of the placebo effect.

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Reconstructing Research Integrity pp 19–36 Cite as

Blind Spots in Research Integrity Policy: How to Identify and Resolve Them

• Barbara Redman 2  
• First Online: 24 March 2023

210 Accesses

Blind spots are a type of biased attention/perception, an inevitable side effect of viewing an issue/problem through a particular lens/frame. Policies guiding/regulating a field must regularly be examined through alternate lenses to find currently out-of-favor views that might suggest a solution to a problem. An example is the current conceptualization of research misconduct including its depiction in regulation. Current policy requires a good faith whistleblower to file an allegation, assumes that the institution hosting the research can assure nonbiased, fair management of that allegation, and that this same institution has not contributed to the accused individual’s actions under a poor research climate. Empirical research and normative scholarship have called all of these assumptions into question, signaling need for a better RM policy. It is good news that the ORI has announced a request for information on the 2005 PHS policies on research misconduct—they need to be rethought.

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Armond, A. C., Gordijn, B., Lewis, J., Hosseini, M., Bodnar, J., Holm, S., & Kakuk, P. (2022). A scoping review of the literature featuring research ethics and research integrity cases. BMC Medical Ethics, 22 (1), 50. https://doi.org/10.1186/s12910-021-00620-8

Article   Google Scholar  

Bierer, B. E., & Meloney, L. G. (2022). Strategies to optimize inclusion of women in multi-national trials. Contemporary Clinical Trials, 117 , 106770. https://doi.org/10.1016/j.cct.2022.106770

Bosk, C. L., & Pedersen, K. Z. (2019). Blind spots in the science of safety. The Lancet, 393 (10175), 978–979. https://doi.org/10.1016/S0140-6736(19)30441-6

Bramstedt, K. A. (2021). Integrity watchdogs, lap dogs, and dead dogs. Accountability in Research, 28 (3), 191–195. https://doi.org/10.1080/08989621.2020.1821370

Bruns, A., & Taubert, N. (2021). Investigating the blind spot of a monitoring system for article processing charges. Publications, 9 (3), 41. https://doi.org/10.3390/publications9030041

Byrn, M. J., Redman, B. K., & Merz, J. F. (2016). A pilot study of universities’ willingness to solicit whistleblowers for participation in a study. American Journal of Bioethics: Empirical Bioethics, 4 (4), 64–67.

Google Scholar  

Capron, A. M. (2017). Building the next bioethics commission. Hastings Center Report, 47 (3), S4–S9. https://doi.org/10.1002/hast.710

Centola, D. (2018). How behavior spreads . Princeton University Press.

Book   Google Scholar  

Cottingham, M. D., & Fisher, J. A. (2022). Gendered logics of biomedical research: Women in U. S. Phase 1 clinical trials. Social Problems, 69 (2), 492–509. https://doi.org/10.1093/socpro/spaa035

Cragoe, N. G. (2019). Oversight: Community vulnerabilities in the blind spot of research ethics. Research Ethics, 15 (2), 1–15. https://doi.org/10.1177/1747016117739936

De Cremer, D., & Moore, C. (2020). Toward a better understanding of behavioral ethics in the workplace. Annual Review of Organizational Psychology and Organizational Behavior, 7 , 369–393. https://doi.org/10.1146/annurev-orgpsych-012218-015151

De Klerk, J. J. (2017). “The devil made me do it!” an inquiry into the unconscious “devils within” of rationalized corruption. Journal of Management Inquiry, 26 (3), 254–269. https://doi.org/10.1177/1056492617692101

De Vries, R. (2022). A tale of two bioethics. Perspectives in Biology and Medicine, 65 (1), 133–142. https://doi.org/10.1353/pbm.2022.0008

Erikainen, S., Friesen, P., Rand, L., Jongsma, K., Dunn, M., Sorbie, A., McCoy, M., Bell, J., Burgess, M., Chen, H., Chico, V., Cunningham-Burley, S., Darbyshire, J., Dawson, R., Evans, A., Fahy, F., Finlay, T., Frith, L., Goldenbert, A., et al. (2020). Public involvement in the governance of population-level biomedical research: Unresolved questions and future directions. Journal of Medical Ethics, 47 . Oct 6 online ahead of print. https://doi.org/10.1136/medethics-2020-106530

Fisher, J. A. (2020). Adverse Events . New York University Press.

Flake, J. K. (2021). Strengthening the foundation of educational psychology by integrating construct validation into open science reform. Educational Psychologist, 56 (2), 132–141. https://doi.org/10.1080/00461520.2021.1898962

Flake, J. K., Davidson, I. J., Wong, O., & Pek, J. (2022). Construct validity and the validity of replication studies: A systematic review. American Psychologist, 77 (4), 576–588. https://doi.org/10.1037/amp0001006

Flake, J. K., & Fried, E. I. (2020). Measurement schmeasurement: Questionable measurement practices and how to avoid them. Applied Psychological Science, 3 (4), 456–465.

Fossheim, H. J. (2019). Past responsibility: History and the ethics of research on ethnic groups. Studies in History and Philosophy of Biology and Biomedical Science, 73 , 35–43. https://doi.org/10.1016/j.shpsc.2018.11.003

Friesen, P., & Glligorov, N. (2022). White ignorance in pain research: Racial differences and racial disparities. Kennedy Institute of Ethics Journal, 32 (2), 205–235. https://doi.org/10.1353/ken.2022.0012

Gillespie, A., & Reader, T. E. (2018). Patient-centered insights: Using health care complaints to reveal hot spots and blind spots in quality and safety. Milbank Quarterly, 96 (3), 530–567. https://doi.org/10.1111/1468-0009.12338

Goldenberg, M. J. (2021). Vaccine hesitancy: Public trust . University of Pittsburgh Press.

Greer, S. L., & Trump, B. (2019). Regulation and regime: The comparative politics of adaptive regulation in synthetic biology. Policy Sciences, 52 , 505–524. https://doi.org/10.1007/s11077-019-09356-0

Hauser, D. J., & Schwarz, N. (2016). Medical metaphors matter: Experiments can determine the impact of metaphors on bioethical issues. American Journal of Bioethics, 16 (10), 18–19. https://doi.org/10.1080/15265161.2016.1214311

Hedlund, M. (2014). Ethics expertise in political regulation of biomedicine: The need for democratic justification. Critical Policy Studies, 8 (3), 282–299. https://doi.org/10.1080/19460171.2014.901174

Holman, B. (2021). What, me worry? Research policy and the open embrace of industry-academic relations. Frontiers in Research Metrics and Analytics, 6 , 600706. https://doi.org/10.3389/frma.2021.600706

Huistra, P., & Paul, H. (2022). Systemic explanations of scientific misconduct: Provoked by spectacular cases of norm violation? Journal of Academic Ethics, 20 , 51–65. https://doi.org/10.1007/s10805-020-09389-8

Iribarren, A., Diniz, M. A., Merz, C. N., Shufelt, C., & Wei, J. (2022). Are we any WISER yet? Progress and contemporary need for smart trials to include women in coronary artery disease trials. Contemporary Clinical Trials, 117 , 106762. https://doi.org/10.1016/j.cct.2022.106762

Kaptein, M., & van Helvoort, M. (2019). A model of neutralization techniques. Deviant Behavior, 40 (10), 1260–1285. https://doi.org/10.1080/01639625.2018.1491696

Klincewicz, M. (2022). Institutional trust in medicine in the age of artificial intelligence . research.tilburguniversity.edu

LeBaron, G., Mugge, D., Best, J., & Hay, C. (2022). Blind spots in IPE: Marginalized trends in contemporary capitalism. Review of International Political Economy, 28 (2), 283–294. https://doi.org/10.1080/09692290.2020.1830835

Lodge, M. (2019). Accounting for blind spots, p 29-48. In T. Bach & K. Wegrich (Eds.), The blind spots of public bureaucracy and the politics of non-coordination . Springer International Publishing.

Maor, M. (2020). Policy over- and under-design: An information quality perspective. Policy Sciences, 53 , 395–411. https://doi.org/10.1007/s11077-020-09388-x

Markowitz, D. M. (2020). The deception faucet: A metaphor to conceptualize deception and its detection. New Ideas in Psychology, 59 , 100816. https://doi.org/10.1016/j.newideapsych.2020.100816

Mirti, M. N., Bowser, G., Cid, C. R., & Harris, N. C. (2021). Overcoming blind spots to promote environmental justice research. Trends in Ecology & Evolution, 36 (4), 269–273. https://doi.org/10.1016/j.tree.2020.12.011

Neff, M. W. (2020). How academic science gave its soul to the publishing industry. Issues in Science & Technology, 36 (2), 35–43.

Pollack, C. E., Soulos, P. R., Herrin, J., Xu, X., Cjristakis, N. A., Forman, H. P., Hu, J. B., Killelea, B. K., Wang, S., & Gross, C. P. (2017). The impact of social contagion on physician adoption of advanced imaging tests in breast cancer. JNCI J of the National Cancer Institute, 109 (8), djw330. https://doi.org/10.1093/jnci/djw330

Reynolds, A. S. (2022). Understanding metaphors in the life sciences . Cambridge University Press.

Rolin, K. (2020). In J. Simon (Ed.), Trust in science . The Routledge Handbook of Trust and Philosophy.

Chapter   Google Scholar  

Shea, C. T., Lee, J., Menon, T., & Dong-Kyun, I. (2019). Cheaters hide and seek: Strategic cognitive network activation during ethical decision making. Social Networks, 58 , 143–155. https://doi.org/10.1016/j.socnet.2019.03.005

Shi, Y., Pollack, C. E., Soulos, P. R., Herrin, J., Christakis, N. A., Xu, X., & Gross, C. P. (2019). Association between degrees of separation in physician networks and surgeons’ use of perioperative breast magnetic resonance imaging. Medical Care, 57 (6), 460–467. https://doi.org/10.1097/MLR.0000000000001123

Smith, C. P., & Freyd, J. J. (2014). Institutional betrayal. American Psychologist, 69 (6), 575–586. https://doi.org/10.1037/a0037564

Spagnolo, P. A., Lorell, B. H., & Joffe, H. (2022). Preface to theme issue on women’s health and clinical trials. Contemporary Clinical Trials, 119 , 106837.

Titus, S. L., Wells, J. A., & Rhoades, L. J. (2008). Repairing research integrity. Nature, 453 (7198), 980–982.

Verschraegen, G. (2018). Regulating scientific research: A constitutional moment? Journal of Law & Society, 45 (S1), S163–S184.

Walker, R. L., Cottingham, M. D., & Fisher, J. A. (2018). Serial participation and the ethics of phase 1 healthy volunteer research. Journal of Medicine and Philosophy, 43 , 83–114. https://doi.org/10.1093/jmp/jhx033

Wilholt, T. (2016). Collaborative research, scientific communities, and the social diffusion of trustworthiness. In M. S. Brady & M. Fricker (Eds.), The epistemic life of groups: Essays in the epistemology of collectives . Oxford University Press.

Williams, E. G. (2015). The possibility of an ongoing moral catastrophe. Ethical Theory and Moral Practice, 18 (5), 971–982.

Zayas, V., Sridharan, V., Lee, R. T., & Shoda, Y. (2019). Addressing two blind spots of commonly used experimental designs: The highly-repeated within-person approach. Social and Personality Psychology Compass, 13 (9), e12487. https://doi.org/10.1111/spc3.12487

Zwart, H. (2017). Tales of research misconduct . Library of Ethics and Applied Philosophy.

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Redman, B. (2023). Blind Spots in Research Integrity Policy: How to Identify and Resolve Them. In: Reconstructing Research Integrity. Springer, Cham. https://doi.org/10.1007/978-3-031-27111-3_2

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What federal education data shows about students with disabilities in the U.S.

Public K-12 schools in the United States educate about 7.3 million students with disabilities – a number that has grown over the last few decades. Disabled students ages 3 to 21 are served under the federal  Individuals with Disabilities Education Act (IDEA) , which guarantees them the right to free public education and appropriate special education services.

For Disability Pride Month , here are some key facts about public school students with disabilities, based on the latest data from the  National Center for Education Statistics (NCES) .

July is both Disability Pride Month and the anniversary of the Americans with Disabilities Act. To mark these occasions, Pew Research Center used federal education data from  the National Center for Education Statistics  to learn more about students who receive special education services in U.S. public schools.

In this analysis, students with disabilities include those ages 3 to 21 who are served under the federal  Individuals with Disabilities Education Act (IDEA) . Through IDEA, children with disabilities are guaranteed a “free appropriate public education,” including special education and related services.

The 7.3 million disabled students in the U.S. made up 15% of national public school enrollment during the 2021-22 school year. The population of students in prekindergarten through 12th grade who are served under IDEA has grown in both number and share over the last few decades. During the 2010-11 school year, for instance, there were 6.4 million students with disabilities in U.S. public schools, accounting for 13% of enrollment.

The number of students receiving special education services temporarily dropped during the coronavirus pandemic – the first decline in a decade. Between the 2019-20 and 2020-21 school years, the number of students receiving special education services decreased by 1%, from 7.3 million to 7.2 million. This was the first year-over-year drop in special education enrollment since 2011-12.

The decline in students receiving special education services was part of a 3% decline in the overall number of students enrolled in public schools between 2019-20 and 2020-21. While special education enrollment bounced back to pre-pandemic levels in the 2021-22 school year, overall public school enrollment remained flat.

These enrollment trends may reflect some of the learning difficulties and health concerns students with disabilities and their families faced during the height of the COVID-19 pandemic , which limited or paused special education services in many school districts.

Many school districts struggle to hire special education professionals. During the 2020-21 school year, 40% of public schools that had a special education teaching vacancy reported that they either found it very difficult to fill the position or were not able to do so.

Foreign languages (43%) and physical sciences (37%) were the only subjects with similarly large shares of hard-to-fill teaching vacancies at public schools that were looking to hire in those fields.

While the COVID-19 pandemic called attention to a nationwide teacher shortage , special education positions have long been among the most difficult for school districts to fill .

The most common type of disability for students in prekindergarten through 12th grade involves “specific learning disabilities,” such as dyslexia.  In 2021-22, about a third of students (32%) receiving services under IDEA had a specific learning disability. Some 19% had a speech or language impairment, while 15% had a chronic or acute health problem that adversely affected their educational performance. Chronic or acute health problems include ailments such as heart conditions, asthma, sickle cell anemia, epilepsy, leukemia and diabetes.

Students with autism made up 12% of the nation’s schoolchildren with disabilities in 2021-22, compared with 1.5% in 2000-01.  During those two decades, the share of disabled students with a specific learning disability, such as dyslexia, declined from 45% to 32%.

The percentage of students receiving special education services varies widely across states. New York serves the largest share of disabled students in the country at 20.5% of its overall public school enrollment. Pennsylvania (20.2%), Maine (20.1%) and Massachusetts (19.3%) serve the next-largest shares. The states serving the lowest shares of disabled students include Texas and Idaho (both 11.7%) and Hawaii (11.3%).

Between the 2000-01 and 2021-22 school years, all but 12 states experienced growth in their disabled student populations. The biggest increase occurred in Utah, where the disabled student population rose by 65%. Rhode Island saw the largest decline of 22%.

These differences by state are likely the result of inconsistencies in how states determine which students are eligible for special education services and challenges in identifying disabled children.

The racial and ethnic makeup of the nation’s special education students is similar to public school students overall, but there are differences by sex.  About two-thirds of disabled students (65%) are male, while 34% are female, according to data from the 2021-22 school year. Overall student enrollment is about evenly split between boys and girls.

Research has shown that decisions about whether to recommend a student for special education may be influenced by their school’s socioeconomic makeup, as well as by the school’s test scores and other academic markers.

Note: This is an update of a post originally published April 23, 2020.

About 1 in 4 U.S. teachers say their school went into a gun-related lockdown in the last school year

About half of americans say public k-12 education is going in the wrong direction, what public k-12 teachers want americans to know about teaching, what’s it like to be a teacher in america today, race and lgbtq issues in k-12 schools, most popular.

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The national federation of the blind jernigan institute research advisory council, nfb research mission:.

The National Federation of the Blind Jernigan Institute (NFBJI) is the first research and training facility developed and directed by blind people. The NFBJI is committed to promoting innovative research concerning blindness to help deepen our understanding of the real problems that face blind people and to help the world’s blind increase independence, self-respect, and self-determination. NFBJI research has included the investigation of new approaches toward the education and rehabilitation of the blind; attitudes toward the blind; innovations relating to the use of Braille; quality of life issues; and cutting-edge technologies, products, and services developed by and for the blind.

To advance its research mission, the NFBJI has created a process by which researchers can collaborate with the NFB on research projects, obtain assistance or advice, or obtain help recruiting participants for their research studies.

Research Advisory Council:

The RAC is a group of uniquely qualified individuals who serve as a consultative body to the NFBJI on research priorities. The RAC identifies appropriate independent and collaborative research projects and, through research, pursues opportunities to strengthen the breadth and depth of influence of the NFBJI in the blindness research arena.

The 2017 Members of the Research Advisory Council are:

• Edward Bell, Ph.D. , director, Professional Development and Research Institute on Blindness, Louisiana Tech University

• Lou Ann Blake, J.D., deputy executive director, the National Federation of the Blind Jernigan Institute

• Curtis Chong , manager of assistive technology, the New Mexico Commission for the Blind

• Seth Lamkin, grant program officer, the National Federation of the Blind

• Anil Lewis, executive director, the National Federation of the Blind Jernigan Institute

• Matt Maurer, Ph.D., professor of instructional technology, Butler University

• Fredric Schroeder, Ph.D. , research professor, San Diego State University

• Natalie Shaheen, educational consultant

• Arielle Silverman, Ph.D. , disability research consultant

• Cary Supalo, Ph.D. , visiting scientist, Purdue University; research developer, the Educational Testing Service

• Eric Vasiliauskas, M.D. , associate clinical director, Inflammatory Bowel Disease Program, Cedars-Sinai Medical Center

Research Topics of Interest to the NFBJI:

• youth and mentoring.

Identification of blind youth who have learned how to use a personal computer and investigation of how they acquired such learning

• Braille and Literacy

The impact of refreshable Braille displays on reading fluency

The impact of the length of Braille displays on reading comprehension

The most efficient ways to read with refreshable Braille

How to improve the efficiency of refreshable Braille displays

How electronic format has changed Braille teaching strategies

Effective Braille instruction, and strategies to combat poor Braille instruction

Environmental influences on Braille reading fluency

Techniques used by fast Braille readers, including how they were taught

Improved methodologies for providing the blind with access to visual information

Best practices for the blind to understand visual information through non-visual methods

Improvements in the creation of tactile graphics

Strategies for teaching visual intelligence

Impact of the age at which a person becomes blind

What can be learned about the brain of the blind through MRI scan studies

• Adults in Rehabilitation, Education, and Employment

The most effective methods for the blind to find employment

The impact of parent advocacy on the employment of blind children

Barriers faced by blind adults entering science, technology, engineering, and math professions

The Impact of exposure to successful blind people at blind consumer conventions on outcomes achieved by vocational rehabilitation counselors

Case studies of teachers of the blind achieving exceptional results with students

Case studies of blind students with additional disabilities who are learning Braille

Recruitment of Blind and Low Vision Research Participants:

Are you a researcher interested in working with the National Federation of the Blind Jernigan Institute to recruit participants for your study? Please complete the online Research Review Form  to tell us a bit about your study and what the experience will be like for participants. This information will help readers decide if they would like to participate in the study. We will review this information for completeness and will let you know if more detail is needed to inform the potential participants about the study. Please contact Lou Ann Blake  for additional information.

Research Projects of Interest:

1. at&t persons with disabilities communications services.

Researcher: Paul Wong

Purpose of Project: to build a working knowledge of how to improve technology and communications services, as well as the marketing of such services, to the blind, deaf, hard of hearing, and/or cognitively impaired communities

Sponsoring Organization: Kantar Added Value/AT&T

2. GRE Usability Study

Researchers: Carlos Cavalie, Mark Hakkinen

Purpose of Project: to examine the accessibility and usability of the Graduate Record Exam (GRE) for screen reader users and screen magnification users and to help the Educational Testing Service improve the accuracy and fairness of assessments for students with visual disabilities. The focus is on methods of testing, not participant ability.  

Sponsoring Organization: Educational Testing Service

3. Transportation Accessibility Needs of Individuals with Vision Loss

Researcher: Danene Fast

Purpose of Project: to gather opinions of consumers with visual impairments concerning recommended training for public transportation workers to address the accessibility needs of passengers with visual impairments

 Sponsoring Organization: The Ohio State University

4. Experiences of Those with Visual Impairments in Physical Activity/Education

Researcher: Justin Haegele

Purpose of Project: to understand the meaning of experiences in physical education and physical activity among individuals with visual impairments to provide insight into how educational practices should be changed to enhance these experiences 

Sponsoring Organization: Old Dominion University

Blind Graduate Students Seeking a Mentor:

If you are a blind masters or PhD student and are interested in the guidance and support of a Research Advisory Council member to serve as mentor and/or informal advisor to you in your research, please contact Lou Ann Blake .

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Unblinding in Randomized Controlled Trials: A Research Ethics Case

Ayesha bhatia.

research study coordinator in the Department of Psychiatry and Behavioral Sciences at Northwestern University Feinberg School of Medicine

Paul S. Appelbaum

Dollard Professor of Psychiatry, Medicine, & Law, the director of the Division of Law, Ethics, and Psychiatry, and the director of the Center for Research on Ethical, Legal & Social Implications of Psychiatric, Neurologic & Behavioral Genetics at Columbia University College of Physicians & Surgeons

Katherine L. Wisner

Norman and Helen Asher Professor of Psychiatry and Behavioral Sciences and Obstetrics and Gynecology, and the director of the Asher Center for the Study and Treatment of Depressive Disorders at Northwestern University Feinberg School of Medicine

A pregnant woman was enrolled in a double-blind randomized controlled trial (RCT) in which participants were randomized to a placebo or a drug being tested to prevent a hypertensive complication. After completing the trial, the research participant insisted on being told which drug she received to prepare for a future pregnancy. This case highlights an element of RCT procedure that has received minimal attention—whether to unblind study participants at the end of their participation. Given that unblinding is not standard practice for nonserious adverse events, what actions are justifiable for the investigators to take? To synthesize the information about this case, we used the CASES model, created by the National Center for Ethics in Health Care to analyze ethics cases. Ethical principles that guide research emphasize communication with participants and the importance of reducing harm within the constraints of the scientific goals. Participants may value knowing which drug they received for future health care decision-making. We review information about the benefits and harms of unblinding.

Randomization was introduced in the 1920s as a tool to maximize the likelihood that varying individual characteristics that may affect outcomes are distributed evenly among conditions in experimental clinical trials. Outcomes of the study then can be attributed with greater confidence to the intervention under investigation. 1 For example, sociodemographic characteristics can influence health outcomes but, if randomization is successful, will be distributed more or less equally across the study arms. When that occurs, differences observed in outcomes between arms are less likely to be due to an association between demographic variables (such as socioeconomic status) and outcomes and more likely to represent a treatment effect.

Randomized controlled trials (RCTs) were originally developed for use in agricultural experiments. One of the first RCTs in a clinical setting was a study of streptomycin for tuberculosis in the United Kingdom in 1946. Randomization and allocation concealment were implemented for both participants and investigators involved in the study. 2 In psychiatric research, an early RCT focused on the efficacy of lithium for the treatment of mania at the Aarhus University Psychiatric Institute in Denmark in 1952. 3 RCTs are now considered the gold standard in clinical trial design. 4

Another frequent component of an RCT is blinding, or the concealment of group allocation from individuals involved in a clinical research study. 5 Blinding minimizes bias, which is the risk that knowledge of the treatment assignment will influence both the subjects’ and assessor’s ratings of the outcome. It may also equalize the placebo effect across conditions. Double-blinded trials yield smaller—and presumably more accurate—estimates of treatment effect sizes than do non-double-blinded trials. 6 In a single-blind study, the participant is unaware of the treatment allocation. In a double-blind trial, both the participant and all outcome evaluators are not aware of the randomization assignment. Double-blind trials are the most employed models for RCTs. 7

A review of RCT unblinding indicated that only 45% of investigators informed either all or most participants of their treatment allocation after they completed the trial, while 55% did not inform any participants or informed only those who asked. 8 The main reasons investigators did not unblind participants at the end of their participation were failure to consider this option (40%) and to avoid biasing results at study follow-up if the study was still ongoing (24%). 9

Researchers agree that unblinding should occur for the patient’s safety when a serious adverse event (SAE) transpires and knowledge of the study drug could dictate the intervention to mitigate the health risk. 10 To illustrate with a hypothetical example, consider a participant being treated for major depressive disorder in an RCT comparing the antidepressants sertraline and nortriptyline. She overdoses on the study medication and is taken to an emergency room. The physician contacts the principal investigator to determine the identity of the study drug, since the toxicity of the two drugs differs and the appropriate treatment depends upon drug identity. Tricyclics have cardiac toxicity, whereas sertraline toxicity can produce serotonin syndrome. These adverse reactions require different emergency medical treatments.

The issue of unblinding separate from the occurrence of an SAE has received less consideration. No standard practice exists for informing participants of their treatment allocation or the results of the trial. 11 Information about whether participants will be unblinded at any point is not a requirement for inclusion in research protocols submitted to institutional review boards (IRBs). The U.S. Department of Health and Human Services regulations (45 C.F.R. 46 and 21 C.F.R. 50 and 56, respectively) are silent regarding informing research subjects about individual treatment assignments or results. They neither directly require nor disallow disclosure. 12

We present a case below to demonstrate the issues two of us experienced when a participant in an RCT requested to be told the identity of her drug treatment. Some details of the case have been changed to preserve anonymity. We used the National Center for Ethics in Health Care’s CASES model as the process for organizing the case discussion. 13 The CASES model incorporates the following steps: clarify the consultation request, assemble the relevant information, synthesize the information, explain the synthesis, and support the consultation process. We reviewed publications about unblinding trial participants and details of the case to provide recommendations.

CLARIFY THE CONSULTATION REQUEST: CASE BACKGROUND

A pregnant woman was enrolled in a double-blind RCT in which participants were randomized in a one-to-one ratio to a placebo or to a drug being tested to prevent a severe hypertensive complication of pregnancy. The disease increases the risk for maternal and neonatal morbidity and mortality. No effective prophylactic therapy exists; hence, immediate delivery, usually preterm, is the indicated intervention. 14

The participant had a complicated pregnancy history, as required for inclusion in this RCT. Her first pregnancy led to a very premature delivery with fetal demise. Her second and third pregnancies resulted in miscarriage. She participated in the RCT during her fourth pregnancy, which resulted in a healthy, full-term newborn with no obstetrical or neonatal complications.

After her participation in the study ended, she contacted the study team and insisted that she be told her drug assignment. As part of the initial consent process, the investigator explained the rationale for maintaining the blind during the study, which the woman accepted and apparently understood during her participation. She did not ask about unblinding during that time.

ASSEMBLE THE RELEVANT INFORMATION

The study was designed to evaluate safety for administration of the study medication to pregnant women at risk for severe hypertensive disorder. The drug being tested in this RCT was available by prescription for other indications not specific to pregnancy; however, obstetricians would be reluctant to prescribe it before the safety data were available from the study. The former participant stated that she deserved to have the choice about whether to search for a physician to prescribe it if her obstetrician would not. She also correctly stated that she was monitored closely for any negative outcomes during her participation in the RCT and, if she were taking the study drug, she tolerated it well and had a good outcome, which would be important for her prescriber to know. In her view, she was being disadvantaged by not knowing the identity of the study drug. Neither protocol nor consent form included any statement about postparticipation identification of the study drug’s identity.

The investigation included a placebo comparison to an active drug. A common assumption is that the placebo has no activity and no effect on the positive outcome. However, this view is not correct. Placebos are associated with substantial effects in medical studies. 15 The placebo-treatment effect occurs in a psychosocial context. The placebo interacts with internal and external stimuli to change the functional neurobiology of the participant’s brain during the procedures inherent in an RCT. For example, the same brain mechanisms that are activated by drugs can also be activated by the placebo. 16 “No drug” is not the same as “placebo drug.”

This case poses multiple questions. Given the information in the case presentation and that unblinding is not standard practice except in instances of SAEs, what actions are ethically justifiable for the investigators to consider? 17 Does an individual have the right to find out her treatment allocation at the termination of her participation? Can a research team refuse to disclose a participant’s treatment allocation if the participant insists on knowing it? What are the ethics surrounding a research team’s decision-making to decide whether to disclose the identity of a participant’s treatment? Can investigators refuse to disclose the allocation if the participant’s physician believes that future clinical management would be compromised by not knowing the identity of the treatment? What are the steps that should be taken if the decision for unblinding is made?

To analyze this case, we reviewed medical facts, the patient’s preferences and interests, the sponsor’s preferences and interests, and ethical principles applicable to RCTs. Multiple databases, including PubMed, Medline, and Google Scholar, were searched for relevant articles in English. The Medline search (1980-2019) of “unblinding” and “treatment allocation” revealed 10 articles, “unmasking” and “treatment allocation” 4 articles, and “unblinding” and “ethics” 11 articles; the PubMed search (1980-2019) of “unblinding” and “treatment allocation” revealed 13 articles, “unmasking” and “treatment allocation” 4 articles, and “unblinding” and “ethics” 13 articles. The nine articles that discussed unblinding in double-blind RCTs were selected for review. Examples of excluded publications were those that described nonblind studies or maintaining the blind within studies. Additional articles were used to provide supporting evidence and clarify topics discussed in the selected articles. After reviewing basic ethics guidance, we will describe the findings of the literature review.

SYNTHESIZE THE INFORMATION

Ethical foundations..

Although standard practice in clinical trials has been not to unblind participants if no SAE occurs, failure to do so may conflict with the following generally held ethical formulations. 18

The Declaration of Helsinki was created by the World Medical Association to serve as a guideline when conducting human subjects research. The Declaration stresses informed consent, confidentiality of data, vulnerable populations, requirements of protocols, a scientific rationale for conducting the study, and review of the study by an ethics committee. 19 Although the Declaration notes that “[a]ll medical research subjects should be given the option of being informed about the general outcome and results of the study,” it does not specifically address release of information regarding study assignment. 20 However, the requirement that “sponsors, researchers and host country governments should make provisions for post-trial access for all participants who still need an intervention identified as beneficial in the trial” could be taken as a rationale for disclosure of the treatment received in cases in which benefit is likely. 21

The principles described in The Belmont Report laid a foundation for regulations regarding the ethics of human subjects research in the United States. 22 Among other effects, these principles obligate biomedical researchers to maximize benefits to the participants, within the constraints of the scientific aims of the study, while minimizing harm. 23 In relation to the case on which we are focused, the issue is whether avoidable harm was being done by not disclosing the study intervention postparticipation. Not disclosing the treatment intervention could risk harm for the individual and limit benefits, especially if the undisclosed treatment compromised future decision-making about the individual’s health.

The four principles of biomedical ethics identified by Beauchamp and Childress are frequently used to structure an ethical approach to research in health care. 24 These principles, which track those identified in The Belmont Report, are autonomy, nonmaleficence, beneficence, and justice. Respect for autonomy entails providing participants with sufficient information and time to understand the research. The principle of nonmaleficence includes the imperative to do no harm, while beneficence prioritizes optimizing the well-being of participants. Justice dictates the fair distribution of benefits and harms across populations of subjects. 25 With regard to the issue at hand, the principles of autonomy, nonmaleficence, and beneficence apply. Autonomy might have been compromised because the individual was not given information at the time of consent about the investigator’s plan regarding unblinding after participation in the trial. The withheld information could impact the individual’s future treatment, which might violate the principles of nonmaleficence, especially if she endured harm after participation, and beneficence, due to the priority for optimizing the well-being of the individual.

HIPAA privacy rule.

The Health Insurance Portability and Accountability Act’s Privacy Rule is applicable to clinical research in the U.S. conducted by covered entities (including almost all hospitals and most clinics) that involves access to or use of protected health information. With relevance to this case, under HIPAA, research participants have the right to access information generated in a research study if it is considered part of the institution’s designated record set. This set includes anything in a medical record generated by a HIPAA-covered entity and may include research records. One permitted exception to this rule applies to clinical trials; that is, the individual’s access rights are suspended while the trial is in progress if the participant provided consent to its being withheld prior to participation. 26 However, HIPAA requires disclosure on participant request after the trial is concluded. This was not included as a statement in the consent form in the case at hand.

Ethical implications of blinding and unblinding.

One consequence of unveiling the study allocation includes generating possible distrust and confusion for the former participant, especially if they were randomized to the placebo arm. Although potential participants are told during the consent discussion that they may receive a placebo, they nonetheless may believe that they will receive an active intervention, and the disclosure that they received a placebo may result in a loss of trust not only in the research team but also in their clinical relationships, especially if their treating clinicians are involved in the study. 27 Negative effects to unmasking also include the introduction of participant or investigator bias. 28 Unblinded participants could discuss their treatment and outcomes with subjects still involved in the trial or on social media. They may also change their perceptions of symptoms or change their behavior based on awareness of the treatment, which, in the event of long-term follow-up, can influence the outcome measures. They could reveal their treatment to the study investigators, which could bias the ongoing study. Study investigators may consciously or unconsciously view data, analyze outcomes, or report results differently. 29 Studies in which subjects become aware of their randomized assignment during the RCT due to inadequate blinding procedures have larger treatment effect sizes, which may not be valid. 30

There is less risk of bias in unblinding participants who complete their trial while the study is still in progress because the participant no longer provides data on the study outcomes. 31 Moreover, the risk can be mitigated by inclusion of a nonblind medical monitor to undertake the disclosure. 32 The monitor has no data collection or oversight role in the study and interacts with the team only about plans to meet with exiting subjects. This person meets with the participant to disclose the randomized treatment and debrief the participant.

An example of postcompletion unblinding was incorporated into the Prospective Study of Pravastatin in the Elderly at Risk study, a multicenter, randomized, double-blind RCT of the efficacy of pravastatin to prevent vascular disease. Participants were given the option of being unblinded to their treatment allocation after the completion of the entire study. The research team contacted them by letter to thank them for participating in the study, to offer a summary of the results, and to give them an opportunity to be unblinded. Participants were asked to indicate when a study nurse could contact them to be unblinded or given the option of not being contacted further. A postage-paid return envelope was provided. Participants who requested to be unblinded were contacted by a study nurse who informed them of their treatment allocation and cholesterol levels. A total of 2,067 participants were sent the information about the option of being unblinded, 1,492 (72.2%) participants responded, and 1,391 (93.2% of respondents) chose to be unblinded. No information was given about why participants declined to be unblinded. Many of the unblinded participants reported that they appreciated knowing their study medication allocation. 33 Such gratitude may result in participants having a positive attitude toward and trust in the investigators and research in general, which may lead to enrollment in future studies.

Unblinding procedures.

Unblinding participants so they can make an informed decision about further treatment may be advisable for several reasons. 34 Participants who knew the aggregate results of a trial but not their own treatment allocation reported being frustrated with the situation. 35 Participants may need support to decide whether they wish to know their treatment allocation, especially when the RCT reveals unexpected or unwelcome findings or when one group has much better results than the other. 36 Participants should understand the implications of being unblinded, especially regarding the knowledge that can reasonably be extrapolated from revealing the allocation. They should be told, for instance, that their outcomes, whether positive or negative, may have been due to factors associated with the trial experience other than the treatment modality itself. 37

In our case, the principal investigator discussed with the former participant the risks and possible harms of knowing which medication she received and the potential for disappointment. Potential outcomes were explored by asking her to imagine how she would feel if she learned that she had been assigned to receive the placebo? The study drug? The woman stated that knowing the drug she received during her successful pregnancy would be valuable clinical information in her planning for future pregnancies. If she was on active medication, she could request that treatment for a subsequent pregnancy. If she had received the placebo, she would know that she was able to achieve a successful pregnancy without the study drug (or any other pharmacologic intervention). She was hoping that she had been randomized to the placebo. If she had been treated with the study drug, she was aware that this trial was not testing the drug’s efficacy, which would be determined in a large-scale RCT. She stated that she would probably pursue being treated with the drug if she could find a prescriber, and she understood that she might not be able to get a prescription. If she were not unblinded, she felt that she would be harmed by not having information that could impact her future pregnancy planning.

The process of unblinding should be established early in the protocol planning process and included in the manual of procedures as well as in the consent process. The timing of the dissemination of the information should be optimized to benefit the participant. 38 We propose that it is the researcher’s responsibility to ensure that the participant understands how the research is being conducted, including whether there will be a process of unblinding at completion of participation and, if so, what this will entail. 39

EXPLAIN THE SYNTHESIS

The CASES model illustrates the many ethical issues that surround unblinding. Several themes emerged from the literature review. For unblinding due to an SAE, a nonblind medical monitor who has access to the randomization but does not participate directly in the study can unblind using a set of operationalized rules. This procedure preserves the blind for the study team during the RCT and permits unblinding without introducing bias to an ongoing study. A similar process can be used to unblind participants after participation in the study to maintain the blind for the research team.

Prior to unblinding the participant, the study team can discuss with this person the potential risks and benefits of knowing the treatment allocation. To address the potential distrust that may be introduced by unveiling the study allocation, the monitor can help participants understand the scientific rationale for randomization and use of a placebo and remind them of their agreement to be subject to this process in their consent to the study. To facilitate the transmission of the information to the participant’s clinicians, consent can be obtained to speak with them directly. Having a nonblind medical monitor provide support to a participant after the unblinding process can provide a sense of closure in the relationship between the participant and the study team.

Participants usually appreciate having the opportunity to know the identity of their study treatment. This courtesy may increase their positive perception of research and lead to a greater chance of their participating in future studies or influencing others to do so. Participating in RCTs is optional, and recruitment is a major challenge. Individuals who participate in research take risks to investigate new treatments for the benefit of the general population. Whether there will be an opportunity to be unblinded is an important element of informed consent.

SUPPORT THE CONSULTATION PROCESS: CASE OUTCOME

Following review of our case, the investigators requested that the randomized drug assignment be revealed to the participant. After consultation with the data safety and monitoring committee and the IRB, the decision was made to reveal the identity of her study drug. The nonblind study pharmacist released the identity of the drug to the participant privately, which allowed the rest of the study team to remain blind. The only information available to the pharmacist was the study identification number (as required by the IRB) to protect personal health information. Written consent was obtained from the participant to reveal her identity and contact information to the pharmacist. After learning of her treatment assignment, the participant expressed her appreciation to the research team.

We recommend that consent forms for RCTs include a clear statement about whether, when, and how unblinding will occur. Whether participants will have the choice to learn the blinded treatment to which they were randomized is important information for truly informed consent for the overall RCT. As illustrated by the case example, there may be times when information about treatment assignments is highly salient to participants because it may affect their subsequent medical care. Moreover, with proper procedures, randomized assignments can be unblinded without negatively affecting an ongoing study. Further research should be conducted in relation to the potential implications of unblinding participants. ♦

Contributor Information

Ayesha Bhatia, research study coordinator in the Department of Psychiatry and Behavioral Sciences at Northwestern University Feinberg School of Medicine.

Paul S. Appelbaum, Dollard Professor of Psychiatry, Medicine, & Law, the director of the Division of Law, Ethics, and Psychiatry, and the director of the Center for Research on Ethical, Legal & Social Implications of Psychiatric, Neurologic & Behavioral Genetics at Columbia University College of Physicians & Surgeons.

Katherine L. Wisner, Norman and Helen Asher Professor of Psychiatry and Behavioral Sciences and Obstetrics and Gynecology, and the director of the Asher Center for the Study and Treatment of Depressive Disorders at Northwestern University Feinberg School of Medicine.

CRSP research for RNIB reveals that a quarter of blind and partially sighted people miss out on their disability benefits

New research from the Centre for Research in Social Policy at Loughborough University, produced for RNIB, reveals that more than one in four blind and partially sighted people (83,000) miss-out on the disability benefits they’re entitled to.

Applications being refused and issues with submitting applications were thought to be key factors in the substantial deficit in the take-up of disability benefits among people who are registered blind or partially sighted. Poor communication from the Department for Work and Pensions (DWP) and the challenge of getting to face-to-face appointments were also cited as barriers in the research.

In RNIB’s experience, people with sight loss in employment are also susceptible to barriers caused by welfare stigma and internalised guilt in claiming benefits while in work. Blind and partially sighted people from ethnic minorities are more likely to face multiple barriers to receiving benefits, including potential language barriers and a lack of knowledge and experience regarding the social security system.

This analysis also found benefit claimants can experience confusion about how disability benefit award decisions are made, what evidence is required and the timings at each stage of a benefit application.

Dr Juliet Stone, an author of the report, said: “We know that blind and partially sighted people face multiple barriers to applying for benefits, including a lack of tailored support in the application process, and negative perceptions of the social security system. Our research has highlighted the importance of addressing these shortcomings, with tens of thousands of blind or partially sighted people missing out on disability benefits to which they are entitled. Improving uptake of benefits is not a straightforward task, but without addressing the structural and practical obstacles to claiming disability benefits, thousands of blind and partially sighted people in the UK will remain vulnerable to financial hardship.” Read the full report here

REVIEW article

This article is part of the research topic.

Pine Bark Extract: Nutrition and Metabolism

Pycnogenol ® French maritime pine bark extract in randomized, double-blind, placebo-controlled human clinical studies Provisionally Accepted

• 1 Horphag Research, Switzerland
• 2 Institute for Pharmaceutical and Medical Chemistry, Faculty of Chemistry and Pharmacy, University of Münster, Germany

The final, formatted version of the article will be published soon.

Pycnogenol ® French maritime pine bark extract is a well-known and thoroughly studied patented extract from the bark of Pinus pinaster Ait. ssp. Atlantica. In 39 randomized double-blind, placebo-controlled (RDP) human clinical trials including 2009 subjects, Pycnogenol ® French maritime pine bark extract supplementation for two weeks to six months has been shown to beneficially affect cardiovascular health, chronic venous insufficiency, cognition, joint health, skin health, eye health, women's health, respiratory health and allergies, oral health and sports performance. The mechanisms of action that can explain the respective effects on different conditions in the human body are discussed as well. As investigated in several in vitro, in vivo and in clinical studies, Pycnogenol ® French maritime pine bark extract showed antioxidative effects, antiinflammatory abilities, beneficial effect on endothelial function and reinforcing effects on the extracellular matrix. The present review aims to give a comprehensive overview of currently available "gold standard" RDP trials of Pycnogenol ® 's benefits across various health domains compared to placebo. In addition, some of the processes on which the presented effects of Pycnogenol ® French maritime pine bark extract are based will be elucidated and discussed. This broad overview of RDP studies on Pycnogenol ® in different health domains can be used as a basis for further research on applications and mechanisms of this unique French maritime pine bark extract.

Keywords: Pycnogenol ®, Pine bark extract, placebo controlled, double-blind, antioxidant, antiinflammatory, Endothelial health, cardiovascular

Received: 21 Feb 2024; Accepted: 22 Apr 2024.

Copyright: © 2024 Weichmann and Rohdewald. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY) . The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Franziska Weichmann, Horphag Research, Geneva, Switzerland

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