Number needed to treat
The number needed to treat (NNT) is a way of summarizing the benefit of an intervention to improve health care. The NNT has been proposed to improve quantitative literacy. The calculations are derived from the results of a randomized controlled trial of an intervention.
|Experimental (intervention) group||Cell A||Cell B||Total in experimental group|
|Control group||Cell C||Cell D||Total in control group|
|Total with outcome||Total without outcome|
Measures of efficacy
Deriving the NNT from the odds or risk ratios
For odds ratios less than 1:
For odds ratios greater than 1:
Years-needed-to-treat to add 1 year of life is proposed to estimate treatment effects.
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- Wen L, Badgett R, Cornell J (2005). "Number needed to treat: a descriptor for weighing therapeutic options". Am J Health Syst Pharm 62 (19): 2031–6. DOI:10.2146/ajhp040558. PMID 16174840. Research Blogging.
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- Levy WC, Mozaffarian D, Linker DT, et al. (March 2009). "Years-needed-to-treat to add 1 year of life: a new metric to estimate treatment effects in randomized trials". Eur. J. Heart Fail. 11 (3): 256–63. DOI:10.1093/eurjhf/hfn048. PMID 19164422. Research Blogging.
Tables of NNTs for various treatments: