A randomized trial reports that the relative risk reduction (RRR) of a new drug for MI prevention is 30%, with an absolute risk reduction (ARR) of 1.5%. The Number Needed to Treat (NNT) is:

• A 30
• B 15
• C 3
• D 67 ✓

Explanation

NNT = 1/ARR = 1/0.015 = 66.7 ≈ 67. The NNT represents the number of patients who need to be treated for one patient to benefit (avoid one MI). An RRR of 30% sounds impressive but when the baseline risk (and thus ARR) is small (1.5%), the NNT is high (67), indicating modest absolute benefit. Clinicians use NNT rather than RRR for decision-making because NNT depends on baseline risk and reflects practical therapeutic value.

Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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