NNT definition.

NNT definition.

• A. Number Needed to Treat
• B. Net Negative Test
• C. Number Needed to Terminate
• D. Normalized Number to Trial

Answer: (A)

NNT is the Number Needed to Treat. It’s a way to express how many patients you would need to treat for one additional patient to benefit (for example, to prevent one adverse outcome) over a specified period. The NNT is the inverse of the absolute risk reduction (ARR). ARR is the difference in event risk between not treating and treating: ARR = risk with control − risk with treatment, assuming the outcome is favorable. Therefore, NNT = 1 / ARR. For example, if the treatment reduces the risk of a bad event from 4% to 2% over a year, the ARR is 0.04 − 0.02 = 0.02, and the NNT is 1 / 0.02 = 50. This means you’d need to treat 50 people for that year to prevent one event. NNT is influenced by the time frame and the specific outcome chosen, and you round up to the nearest whole person. If a treatment increases risk, you’d think in terms of a Number Needed to Harm (NNH) rather than NNT.

NNT is the Number Needed to Treat. It’s a way to express how many patients you would need to treat for one additional patient to benefit (for example, to prevent one adverse outcome) over a specified period. The NNT is the inverse of the absolute risk reduction (ARR). ARR is the difference in event risk between not treating and treating: ARR = risk with control − risk with treatment, assuming the outcome is favorable. Therefore, NNT = 1 / ARR.

For example, if the treatment reduces the risk of a bad event from 4% to 2% over a year, the ARR is 0.04 − 0.02 = 0.02, and the NNT is 1 / 0.02 = 50. This means you’d need to treat 50 people for that year to prevent one event. NNT is influenced by the time frame and the specific outcome chosen, and you round up to the nearest whole person. If a treatment increases risk, you’d think in terms of a Number Needed to Harm (NNH) rather than NNT.