What is a Double Blind Trial?

A double-blind study: What is a Double-Blind Trial?

Clinical trials are scientific experimental studies performed to assess the efficacy and evaluate the safety of new potential treatments for certain disorders and conditions.

These studies usually take approximately five years to six years in research and development before reaching the clinical trial phase.

After the different phases of clinical trials are completed, based on the results, the drug or treatment can be made available to the public or rejected by the Food and Drug Administration or FDA.

There are usually three parties or groups involved in the study: the patients or the study participants, the doctors or researchers, the monitoring committee or any other third party.

Single-blind, double-blind, or triple-blind studies can be performed depending on how many parties are unaware of the details of the interventional and placebo groups.

The most trusted and secure clinical trial method is a double-blind trial, as it prevents several forms of bias and ensures the accuracy of the study’s results.

What is a double-blind trial?

Double Blind Clinical Trial - Double Blind Study

Double-Blind Clinical Trial – Double-Blind Study

A double-blind study is an experimental study where the researcher and the participants are unaware of the specifics of the treatment plans and allocations.

In simple terms, neither the participants nor the researchers know which patient is receiving the new treatment and which one is receiving an old treatment option or a placebo drug.

However, new guidelines by CONSORT say that the term double-blind alone does not describe the type of study being performed.

This is because this term doesn’t explain strictly which party was blinded and the specifics of the blinding.

Hence, researchers must specify details rather than use the term double-blind when referring to a study where the researchers and participants were blinded.

How is a double-blind study performed?

For a double-blind trial, participants are divided into two groups: the interventional and placebo groups.

The participants in the interventional group are given the treatment or drug whose effects are being studied.

At the same time, the placebo group may receive different treatments based on the study’s primary aim.

If the study aims to assess whether a new treatment is better than the current treatment, the placebo group will receive the current treatment; if the study aims to find new treatments for a condition, a placebo drug will be given.

Since the researchers or doctors involved are usually the second group to be blinded, the monitoring committee allocates participants to groups.

All the medications are sealed in identical bags and have identical appearances, reducing the risk of a drug being recognized by the doctors or participants.

Advantages of Double-blind trial

A double-blind study has many benefits, the most important of which is a significant reduction of bias.

Bias usually refers to any interpretation of the information that departs from the results. Several forms of bias can occur in a clinical study, and a double-blind trial can help avoid them.

If a doctor is aware of the patients enrolled in the study, in an attempt to increase the chances of success, they may allocate the patients with better chances of overall survival to the interventional group while allocating weaker, less likely-to-survive patients to the placebo group.

This is a form of bias as the results will be skewed and favor the interventional group, although the reality may be different.

Similarly, if a patient is made aware that they are receiving the placebo treatment, they may worsen medically as they don’t believe in the treatment.

Their belief system can ruin their chances; again, it has nothing to do with the efficacy or safety of the drug being tested.

At the same time, if they are receiving the new treatment and are aware of this, they may believe in its efficacy regardless of the actual results, which could skew the data.

This is yet another form of bias that should be avoided if the actual results of the study are to be studied.

Unblinding of a double-blind trial

During a double-blind trial, it is possible for unblinding to occur.

Unblinding, as the name aptly describes, occurs when either of the blinded groups discovers information they weren’t supposed to know.

For example, if a patient finds out which study group they are in during the period of the study, then it is called unblinding.

If unblinding were to occur before the study results were determined, then it is referred to as a form of bias that the researchers are obligated to mention in their final results.

Hence, great care should be taken when performing a double-blind study.

See Also

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What is a Randomized Clinical Trial

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