PMCCPMCCPMCC

Search tips
Search criteria 

Advanced

 
Logo of bmjThe BMJ
 
BMJ. 1995 February 18; 310(6977): 452–454.
PMCID: PMC2548824

The number needed to treat: a clinically useful measure of treatment effect.

Abstract

The relative benefit of an active treatment over a control is usually expressed as the relative risk, the relative risk reduction, or the odds ratio. These measures are used extensively in both clinical and epidemiological investigations. For clinical decision making, however, it is more meaningful to use the measure "number needed to treat." This measure is calculated on the inverse of the absolute risk reduction. It has the advantage that it conveys both statistical and clinical significance to the doctor. Furthermore, it can be used to extrapolate published findings to a patient at an arbitrary specified baseline risk when the relative risk reduction associated with treatment is constant for all levels of risk.

Full text

Full text is available as a scanned copy of the original print version. Get a printable copy (PDF file) of the complete article (720K), or click on a page image below to browse page by page. Links to PubMed are also available for Selected References.

Selected References

These references are in PubMed. This may not be the complete list of references from this article.
  • Evidence-based medicine. A new approach to teaching the practice of medicine. JAMA. 1992 Nov 4;268(17):2420–2425. [PubMed]
  • Laupacis A, Sackett DL, Roberts RS. An assessment of clinically useful measures of the consequences of treatment. N Engl J Med. 1988 Jun 30;318(26):1728–1733. [PubMed]
  • Smith GD, Egger M. Who benefits from medical interventions? BMJ. 1994 Jan 8;308(6921):72–74. [PMC free article] [PubMed]
  • Collins R, Peto R, MacMahon S, Hebert P, Fiebach NH, Eberlein KA, Godwin J, Qizilbash N, Taylor JO, Hennekens CH. Blood pressure, stroke, and coronary heart disease. Part 2, Short-term reductions in blood pressure: overview of randomised drug trials in their epidemiological context. Lancet. 1990 Apr 7;335(8693):827–838. [PubMed]

Articles from The BMJ are provided here courtesy of BMJ Group