What should participants be informed about regarding how many people are in the trial?

• A. The approximate number of participants involved.
• B. The exact current number of participants.
• C. That only the investigators know.
• D. No information about numbers.

Answer: (A)

Informed consent includes giving participants enough context about the trial to understand what they’re joining. The number of people involved helps you gauge the scale of the study and what the results might mean for them. Providing the approximate number of participants involved gives useful context about safety monitoring, the likelihood of detecting rare events, and how generalizable the findings may be. It’s appropriate to share an estimate because enrollment can change over time and across sites, so a precise current tally could be misleading or hard to keep up to date. Saying there’s no information about numbers would deprive participants of important context, and saying only investigators know the number is inaccurate—participants should receive meaningful information about trial size as part of informed consent.