Types of Blinding in Clinical Research..

Blinding is a procedure in which one or more parties in a trial are kept unaware of which treatment arms participants have been assigned to, i.e. which treatment was received.

Blinding is an important aspect of any trial. How a trial was blinded should be accurately recorded in order to allow readers to interpret the results of a study. If blinding is ever broken during a trial on individual participants, it needs to be justified and explained
Why Do We Blind?
Blinding is used to prevent conscious or unconscious bias in the design of a clinical trial and how it is carried out. This is important because bias can affect recruitment and allocation, care, attitudes, assessments, etc.

It is used to ensure the objectivity of participants, study staff, clinicians, data collectors, outcome adjudicators and data analysts.
What Are The Potential Sources Of Bias in a Trial and Who Can And Should Be Blinded?
The relevance of blinding in a randomized clinical trial will vary according to circumstances.

The trial participant
Blinding participants to the treatment they have received is particularly important when the response criteria are subjective, such as alleviation of pain, but less important for objective criteria, such as disease progression (e.g. cancer). If participants are not blinded, knowledge of group assignment may affect their behaviour in the trial and their responses to subjective outcome measures.
For example, a participant who is aware that he is not receiving active treatment may be less likely to comply with the trial protocol. Those aware that they are receiving or not receiving therapy are more likely to provide biased assessments of the effectiveness of the intervention — most likely in opposite directions — than blinded participants.
Clinical staff administering treatment
Similarly, medical staff and clinicians caring for patients should be blinded to treatment allocation to minimise possible bias in patient management and in assessing disease status. Blinded clinicians are much less likely to transfer their attitudes to participants or to provide differential treatment to the active and control (placebo) groups than are unblinded clThe doctor assessing treatment
Blinding of data collectors and outcome adjudicators (sometimes the same individuals) is crucial to ensure unbiased ascertainment of outcomes. For example, in a randomised controlled trial in patients, neither active treatment regimen (tested medication vs. comparator) was superior to placebo when assessed by blinded specialists, but there was an apparent benefit of treatment with the test medication, when unblinded specialists performed the assessments.

1. Types of Blinding in Clinical Research [email protected] | https://clinicalda.blogspot.com

2. Blinding Blinding is a procedure in which one or more parties in a trial are kept unaware of which treatment arms participants have been assigned to , in other words, which treatment was received

3. Types of Blinding Single Blinding Double Blinding Triple Blinding Open Blinding

4. Single Blinding If participants know whether they were assigned to the treatment or control group , they might modify their behavior 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.

5. Single blinding

6. example You have developed a new flu vaccine. In order to test the effectiveness of your new treatment, you run an experiment, giving half of your participants the flu vaccine and the other half a fake vaccine that will have no effect (to control for the placebo effect ). If participants in the control group realize they have received a fake vaccine and are not protected against the flu, they might modify their behavior in ways that lower their chances of becoming sick – frequently washing their hands, avoiding crowded areas, etc. This behavior 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. To prevent such an outcome, in a single-blind study, you hide from the participants which vaccine – real or fake – each of them received.

7. 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.

8. Double Blinding

9. Example In the flu vaccine study that you are running, you have recruited several experimenters to administer your vaccine and measure the outcomes of your participants. If these experimenters knew which vaccines were real and which were fake, they might accidentally reveal this information to the participants, thus influencing their behavior 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. To avoid this, you hide group assignments from both the participants and the experimenters giving the vaccines – a double-blind study.

10. 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 analyzing the data after the experiment has concluded. Researchers may expect a certain outcome and analyze the data in different ways until they arrive at the outcome they expected, even if it is merely a result of chance.

11. Triple blinding

12. Example In your vaccine study, you have also recruited assistants to analyze the data you gathered on flu infection rates. You decide to hide the group assignments from the participants, the people administering the experiment, and the people analyzing the data – a triple-blind study. To achieve triple blinding, you assign each participant to group 1 or group 2, but do not inform the data analysts which number represents which group.

13. Single blind V/S Double blinding

14. Open Blinding Open Blinding is a procedure in which parties in a trial are kept aware of which treatment arms participants have been assigned to , in other words, which treatment was received.

15. Open Blinding OPEN TRIAL LABEL