The Number Needed to Harm (NNH) for a drug causing hepatotoxicity is 150 over 2 years. What does this mean?

• A 150 patients must be treated for one patient to benefit
• B The drug causes hepatotoxicity in 1 out of every 150 patients regardless of duration
• C 150 patients have been harmed in clinical trials over 2 years
• D For every 150 patients treated for 2 years, one additional patient will develop hepatotoxicity compared to control ✓

Explanation

NNH is the reciprocal of the Absolute Risk Increase (ARI). NNH = 150 means that for every 150 patients treated over the specified period (2 years) compared to not treating, one additional patient experiences the harm (hepatotoxicity) attributable to the drug. It is time-dependent and reflects excess harm above the background rate in controls. A lower NNH indicates greater harm potential.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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