Absolute risk reduction — FRCA Primary MCQ

Instant feedback + full explanation. One question, done properly.

ModerateStatistics and Evidence-Based MedicineAbsolute risk reductionFRCA Primary

A trial reports postoperative nausea in 12 of 120 patients receiving drug A and 30 of 120 receiving placebo. What is the absolute risk reduction?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: E — 5%

Risk is 10% with drug A and 25% with placebo, so absolute risk reduction is 15%. The tempting answer of 60% would be relative risk reduction, not absolute risk reduction. Number needed to treat would be about 1/0.15, or 7. The pearl is that absolute measures are usually more clinically interpretable than relative measures.

Reference: RCoA Primary FRCA Syllabus 2026; Altman Practical Statistics for Medical Research