In cohort studies, a Competing Risk refers to what concept?

• A. Death stops follow-up if not primary outcome
• B. Death is the primary outcome
• C. Loss to follow-up is the only competing risk
• D. End of study has no effect

Answer: (A)

In cohort studies, a competing risk is an event that prevents the occurrence or observation of the outcome of interest. Death is a classic competing risk because if a participant dies before they experience the primary outcome, they can no longer have that outcome, so follow-up for that outcome ends. This is why the statement that death stops follow-up if the primary outcome has not occurred best captures the concept. The other ideas don’t fit as well: if death were the primary outcome, it wouldn’t be a competing risk; loss to follow-up is a censoring issue that can complicate analysis but isn’t itself the competing risk in the same sense; the end of study terminates observation but isn’t an event that competes with observing the outcome.