Unblinding in Randomized Controlled Trials: A Research Ethics Case

A pregnant woman was enrolled in a double-blind randomized controlled trial (RCT) in which participants were randomized to a placebo or a drug being tested to prevent a hypertensive complication. After completing the trial, the research participant insisted on being told which drug she received to prepare for a future pregnancy. This case highlights an element of RCT procedure that has received minimal attention-whether to unblind study participants at the end of their participation. Given that unblinding is not standard practice for nonserious adverse events, what actions are justifiable for the investigators to take? To synthesize the information about this case, we used the CASES model, created by the National Center for Ethics in Health Care to analyze ethics cases. Ethical principles that guide research emphasize communication with participants and the importance of reducing harm within the constraints of the scientific goals. Participants may value knowing which drug they received for future health care decision-making. We review information about the benefits and harms of unblinding.