If an exposure reduces the risk of an adverse event, which statement is accurate?

• A. Exposed have lower risk of the adverse event.
• B. Exposed have higher risk of the adverse event.
• C. There is no difference in risk.
• D. The RR cannot be interpreted.

Answer: (A)

When an exposure reduces risk, the incidence of the adverse event is lower in the exposed group than in the unexposed group. In relative risk terms, the risk in the exposed divided by the risk in the unexposed is less than 1, which signals a protective effect. So the statement that exposed have lower risk is accurate. For example, if exposed risk is 2% and unexposed risk is 4%, the RR is 0.5, meaning the exposed have half the risk. The other options would imply no reduction (RR = 1), increased risk (RR > 1), or an uninterpretable measure, which isn’t how RR works in cohort studies.