Fool’s Gold – Why Blinded Trials Aren’t Always Best

March 18, 2020

Written by Clay Smith

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We need not be so quick to think “unblinded” means “lower quality.” There are some compelling reasons why blinding isn’t always best.

Why does this matter?
The double-blinded study is considered to be the gold standard for clinical trials. Some unblinded studies may wrongly be considered as lower quality. Blinding is meant to minimize the bias of patients and the observers. But is blinded always “good” and unblinded always “bad?” This article takes a critical view of blinding and points out some reasons why blinding may not always be best.

Blinded leading the blind

What are the downsides of blinding?

• Decreased recruitment and retention impact trial integrity – It is harder to get patients to participate and stay in trials with a placebo arm if they are blinded.

• If patients feel demoralized, they are more likely to drop out and increase bias due to differential loss to follow up.

• Patients often use online forums to figure out which group they are in. Common side effects effectively unblind the drug anyway.

• It is expensive to make identical placebos.

• Blinding could impact patient safety. Sometimes dosage adjustments are needed, which is tough with blinding. At times, additional treatments are withheld to maintain blinding.

In summary, there are good reasons why blinding may not fit every research situation. Unblinded doesn’t necessarily mean low quality. The authors propose that one alternative is to blind outcome assessors but not patients or clinicians.

Source
Fool’s gold? Why blinded trials are not always best. BMJ. 2020 Jan 21;368:l6228. doi: 10.1136/bmj.l6228.

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