In a randomized trial, which question assesses whether participants were blinded to their assignment?

In a randomized trial, which question assesses whether participants were blinded to their assignment?

• A. Were clinicians blinded to the subjects' group assignment?
• B. Is blinding of outcome assessors unnecessary in trials?
• C. Should all participants be followed for the full duration regardless of retention?
• D. Were subjects masked or blinded to their group assignment?

Answer: (D)

Blinding participants minimizes bias by keeping them unaware of which intervention they received. The question is asking whether participants were kept unaware of their assignment, which is exactly captured by asking if subjects were masked or blinded to their group assignment. This direct phrasing confirms whether participants’ knowledge could have influenced their responses or behavior. Other options shift the focus away from the participant’s level of blinding: one asks about clinicians’ awareness, another questions whether blinding of outcome assessors is needed, and the last concerns follow-up and retention. While all are important in trial design, they do not assess whether the participants themselves were blinded.

Blinding participants minimizes bias by keeping them unaware of which intervention they received. The question is asking whether participants were kept unaware of their assignment, which is exactly captured by asking if subjects were masked or blinded to their group assignment. This direct phrasing confirms whether participants’ knowledge could have influenced their responses or behavior.

Other options shift the focus away from the participant’s level of blinding: one asks about clinicians’ awareness, another questions whether blinding of outcome assessors is needed, and the last concerns follow-up and retention. While all are important in trial design, they do not assess whether the participants themselves were blinded.