In a clinical trial, 100 patients received Drug A and 100 received placebo. Event rate in drug group = 10%, in placebo = 20%. The Number Needed to Treat (NNT) is:
- A 5
- B 10 ✓
- C 15
- D 20
Correct answer: B. 10
Explanation
NNT = 1 / Absolute Risk Reduction (ARR). ARR = Event rate in control − Event rate in treatment = 20% − 10% = 10% = 0.10. NNT = 1/0.10 = 10. This means 10 patients need to be treated with Drug A to prevent one additional adverse event compared to placebo.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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