What is a “blind” or “masked” trial?
Most clinical trials have a “treatment group” (those who receive study drug) and a “control group” (which may receive the current standard of care treatment or placebo). In a “blinded” or “masked” trial, participants are not told which group they are in. The reason for this is to avoid bias. If participants expect to improve on the investigational treatment they may report hopeful signs to researchers simply because they want to believe they are improving. Similarly, physicians and their staff may also be “blinded” to the treatment a trial participant is receiving so that their opinion of how the participant is doing is not affected by any preconceived opinions of the investigational treatment.
