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Compound Evidence InstituteEvidence synthesis · established 2023Graded assessments of compounds, trials, methods and supply
Document set current to 30 July 2026
Defined term · Statistics and inference

Number needed to treat

The reciprocal of the absolute risk difference: the number of people who must be treated for the stated duration for one additional person to benefit. Rises sharply as baseline risk falls.

Document identifier
CEI-GT-070
Series
Defined term
Version
1.0
Published
30 Jul 2026
Last reviewed
30 Jul 2026
Certainty
Not rated

§1Number needed to treat

§1.1Also known as

NNT

§1.2Category

Statistics and inference — Terms describing how effects are estimated and how uncertainty is expressed.

§1.3Related terms

  • Absolute risk difference — The difference in event probability between arms. Depends on baseline risk and is the measure from which a number needed to treat is derived.
Compound Evidence Institute · CEI-GT-070 · https://compoundevidence.com/glossary/number-needed-to-treat/ · retrieved 30 July 2026
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