Blinding is particularly important in drug trials when the study is assessing subjective outcomes, such as relief of pain or anxiety. It isn't always possible to mask the treatments. For example, subjects randomly assigned to follow either a specific exercise regimen or continue their usual level of activity cannot be blinded.
What is the importance of blinding in clinical trials?
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.
What is blinding in epidemiology?
May 25, 2020 Sandesh Adhikari Epidemiology 0 What is Blinding in Research? Blinding, in research, mentions to a practice where the study population or the stakeholders involved in research are not permitted from knowing certain information or treatment, which may somehow influence the study findings.
What are the different types of blinding in research?
There are basically three different types of blinding used in researches: 1. Single blinding or single-masked: In single blinding, only a single stakeholder i.e. either the participant or the investigator is not informed of the nature of treatment the participant is receiving. A trial is called single-blind if only one party is blinded.
What is a blind study in research?
Blinded (or "masked") studies are those in which the subjects, and possibly the investigators as well, are unaware of which treatment the subject is receiving, e.g., active drug or placebo. Blinding is particularly important in drug trials when the study is assessing subjective outcomes, such as relief of pain or anxiety.
Why is blinding important in studies?
Why blinding is necessary Blinding of one or more parties is done to prevent observer bias. This refers to the fact that most (if not all) researchers will have some expectations regarding the effectiveness of an intervention. Blinding of observers provides a strategy to minimize this form of bias.
Why is blinding important in clinical trials?
Blinding is used in Clinical Trials to remove any bias that can be caused intentionally or unintentionally if participants or the research team are aware of who is receiving an active or placebo treatment.
What is blinding and why is it important?
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).
Why is blinding important in an experiment that is testing the effectiveness of a drug?
Good blinding can reduce or eliminate experimental biases that arise from a participants' expectations, observer's effect on the participants, observer bias, confirmation bias, and other sources.
What are blinded studies?
Listen to pronunciation. (BLINE-ded STUH-dee) A type of study in which the patients (single-blinded) or the patients and their doctors (double-blinded) do not know which drug or treatment is being given. The opposite of a blinded study is an open label study.
Why are blind trials good?
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.
How can blinding improve the reliability of the study's results?
Blinding of outcome assessors reduces detection bias. Outcome assessors (study nurses or investigators) who are aware of the actual treatment may unconsciously or intentionally alter their assessment.
Why is blinding important in epidemiology?
Blinding is important in other types of research too. For example, in studies to evaluate the performance of a diagnostic test those perform ing the test must be unaware of the true diagnosis.
Why is blinding important?
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.
What is blinding in a trial?
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.
Why is blind assessment important in double blind trials?
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.
What is double blinding?
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 ...
Is blinding always possible?
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.
Can you blind two active compounds?
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.
What is blinding in research?
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 ...
How to implement 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.
Why incorporate blinding?
Lack of blinding in randomised controlled trials (RCTs) has been shown to be associated with more exaggerated estimated intervention effects, by 9% on average. 1 Studies with subjective outcomes are more likely to show these exaggerated estimates. 2 In a systematic review of 250 RCTs, researchers observed a significant difference in the size of the estimated treatment effect between trials that reported ‘double-blinding’ compared with those that did not (p=0.01), with an overall OR 17% larger in studies that did not report blinding. 3 In addition, studies are often simply described as ‘blind’ or ‘double-blind’ and do not specify who was blinded, 4 which means blinding of one or more of the participants, healthcare providers, outcome assessors and analysts. Identification of who was blinded and how this was achieved would be valuable to assess potential for bias. 5
Why is blinding of outcome assessors important?
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
What happens if you are blinded after enrolling in a study?
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.
What are the methods used to blind an outcome assessor?
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.
How to avoid unblinding?
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.
What is blinding in medical terms?
Blinding. Blinded (or "masked") studies are those in which the subjects, and possibly the investigators as well, are unaware of which treatment the subject is receiving, e.g., active drug or placebo. Blinding is particularly important in drug trials when the study is assessing subjective outcomes, such as relief of pain or anxiety.
What is double blinding in medicine?
Double-blinded: Neither the subjects nor the investigators are aware of the treatment assignment until the end of the trial. A placebo is an inert substance identical in appearance to the active treatment. Its purpose is to facilitate blinding by making the groups as similar as possible in the perception of treatment and to promote compliance.
What is randomization in clinical trials?
Randomization is a method of allocating subjects in a clinical trial to treatment groups such that every subject has an equal chance of receiving any one of the treatments or interventions. This can be achieved by any fair method that assigns subjects in a completely unpredictable fashion. One could use the flip of a coin if there are only two treatment options, but more commonly a table of random numbers or computer-generated random numbers are used. Other methods, such as assigning subjects based on odd or even calendar date, can be "gamed" in a way that biases assignment.
What is Blinding in Research?
Blinding, in research, mentions to a practice where the study population or the stakeholders involved in research are not permitted from knowing certain information or treatment, which may somehow influence the study findings.
What is double blinding in psychology?
Double-blinding or double-masked: Double-blinded study is defined as a study, in which both study population/participant and data collectors/investigators/researchers are not aware of the kind or nature of the treatment given and who receive the treatment. ...
What are the different types of blinding?
Different Types of Blinding: There are basically three different types of blinding used in researches: 1. Single blinding or single-masked: In single blinding, only a single stakeholder i.e. either the participant or the investigator is not informed of the nature of treatment the participant is receiving. A trial is called single-blind ...
What is an unblinded trial?
Unblinded or open level. Unblinding a trial is a necessary process to safeguard participants in the event of medical or safety reasons. The process of unblinding is planned and included in the study protocol. Potential lower efficiency.
Why is double blind important?
Double blind. It prevents research outcomes from being ‘biased’ and not influenced by knowledge of the participant and the researcher. It is a basic tool to prevent conscious and unconscious bias in research. It avoids deception in the research process. Lack of adequate demographic controls.
What is triple blinding?
Triple blinding: A clinical trial or experiment in which neither the subject nor the person governing treatment nor an individual measuring the response to the treatment is aware of the particular treatment received by the subject is known as triple blind.
Who is blinded in triple blinding?
In triple blinding, the study participant, the data investigator or data collector and the data analyzer- all are blinded.
What is the importance of blinding and randomization?
Most, if not all, guidelines, recommendations, and other texts on Good Research Practice emphasize the importance of blinding and randomization. There is, however, very limited specific guidance on when and how to apply blinding and randomization. This chapter aims to disambiguate these two terms by discussing what they mean, why they are applied, and how to conduct the acts of randomization and blinding. We discuss the use of blinding and randomization as the means against existing and potential risks of bias rather than a mandatory practice that is to be followed under all circumstances and at any cost. We argue that, in general, experiments should be blinded and randomized if (a) this is a confirmatory research that has a major impact on decision-making and that cannot be readily repeated (for ethical or resource-related reasons) and/or (b) no other measures can be applied to protect against existing and potential risks of bias.
How many levels of blinding are there?
There are three types or levels of blinding, and each one of them has its use: assumed blinding, partial blinding, and full blinding. With each type of blinding, experimenters allocate subjects to groups, replace the group names with blind codes, save the coding information in a secure place, and do not access this information until a certain pre-defined time point (e.g., until the data are collected or the study is completed and analyzed).
What are the two bias reducing instruments that need to be considered when planning a study?
Among internal validity criteria, randomization and blinding are two commonly recognized bias-reducing instruments that need to be considered when planning a study and are to be reported when the study results are disclosed in a scientific publication.
Why is randomization important in biology?
In other words, randomization enables the application of statistical tests that are common in biology and pharmacology research .
When should randomization and blinding be reported?
Among internal validity criteria, randomization and blinding are two commonly recognized bias-reducing instruments that need to be considered when planning a study and are to be reported when the study results are disclosed in a scientific publication.
Why is rationalization important in research?
Since the costs and resources are not an acceptable argument in discussions on ethical conduct of research, we often engage a defense mechanism, called rationalization, that helps to justify and explain why blinding should not be applied and do so in a seemingly rational or logical manner to avoid the true explanation. Arguments against the use of blinding can be divided into two groups.
What are some examples of psychological barriers?
For example, one may believe that his/her research area or a specific research method has an innate immunity against any risk of bias. Or, alternatively, one may believe that his/her scientific excellence and the ability to supervise the activities in the lab make blinding unnecessary. There is a great example that can be used to illustrate that there is no place for beliefs and one should rather rely on empirical evidence. For decades, compared to male musicians, females have been underrepresented in major symphonic orchestras despite having equal access to high-quality education. The situation started to change in the mid-1970s when blind auditions were introduced and the proportion of female orchestrants went up (Goldin and Rouse 2000 ). In preclinical research, there are also examples of the impact of blinding (or a lack thereof). More specifically, there were studies that reveal substantially higher effect sizes reported in the experiments that were not randomized or blinded (Macleod et al. 2008 ).
What did Bonnie do in her experiment?
History. Bonnie conducts an experiment to examine the effects of media on college women's body image. She gives a sample of women a body image questionnaire, then a week later exposes them to magazine photos of very thin models. Then a week later she administers a posttest designed to assess any changes in body image.
What did Sagles and others do in 2002?
Sagles et al. (2002) conducted a cross-cultural study of the identification of facial expressions. They were careful to use photographs of faces only so that variables like attire and body type could not influence responses. Sagles et al. used the control technique of