NNT From an Odds Ratio or Relative Risk and a Baseline Risk
Number needed to treat from an odds ratio or relative risk and a baseline risk.
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Effect measure
- Odds ratio
- Odds ratio or relative risk
- 0.75
- Baseline risk without treatment
- 20 %
Result: Number needed to treat: 24 for one fewer event (23.75 before rounding up), at a baseline risk of 20%.
The tool opens with these values already filled in. Replace them with your own.
What you enter
- Effect measure
- Odds ratio or relative risk
- Baseline risk without treatment
- Lower 95% confidence limit (optional)
- Upper 95% confidence limit (optional)
How this is calculated
Citation
Mendes D, Alves C, Batel-Marques F. Number needed to treat (NNT) in clinical literature: an appraisal. BMC Med 2017;15:112, formulas 1 and 2. Interval: Altman DG. Confidence intervals for the number needed to treat. BMJ 1998;317:1309-1312. Read the sources: Mendes 2017 (formulas) ↗, Altman 1998 (interval) ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.