This learning resource is linked to the ARR and NNT / NNH Calculator.
Use the ARR and NNT / NNH Calculator
Core Concept
Use comparable adverse-event risks over the same follow-up period. NNT/NNH is rounded up; no confidence intervals or treatment recommendation.
Why the Calculation Matters
Use comparable adverse-event risks over the same follow-up period. NNT/NNH is rounded up; no confidence intervals or treatment recommendation.
Formula and Scientific Basis
ARR = control adverse-event risk − treatment risk; NNT = 1/ARR (fraction); NNH = 1/abs(ARR) when ARR < 0
Inputs and Their Meaning
| Input | Field Type | Unit |
|---|---|---|
| Control adverse-event risk (%) | Number | As specified |
| Treatment adverse-event risk (%) | Number | As specified |
| Shared follow-up period (e.g. 12 months) | Text | As specified |
How to Interpret the Result
Interpret the result with the approved procedure, acceptance criteria, units, assumptions, and the intended pharmaceutical decision in mind.