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Number‐Needed‐to‐Treat (NNT) – Needs Treatment with Care
Author(s) -
Christensen Palle Mark,
Kristiansen Ivar Sønbø
Publication year - 2006
Publication title -
basic and clinical pharmacology and toxicology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.805
H-Index - 90
eISSN - 1742-7843
pISSN - 1742-7835
DOI - 10.1111/j.1742-7843.2006.pto_412.x
Subject(s) - number needed to treat , medicine , meaning (existential) , intensive care medicine , absolute risk reduction , psychological intervention , adverse effect , reduction (mathematics) , relative risk , psychology , psychiatry , psychotherapist , population , pharmacology , mathematics , confidence interval , environmental health , geometry
The “number‐needed‐to‐treat” (NNT) was introduced about 15 years ago and has gained widespread use. It has been claimed to be “easy to understand” and gives “intuitive meaning”. When used to measure the effectiveness of interventions targeting chronic disease processes e.g. atherosclerosis and osteoporosis, NNT (as well as relative and absolute risk reduction) does not capture the crucial time component, a fact that has important consequences: NNT varies over time, it may not mean that adverse events (fractures, myocardial infarctions etc.) are avoided, but simply that they are postponed. Finally, empirical studies indicate that lay people and doctors misunderstand NNT. We recommend that NNT be used with considerable care. There is probably no single effect measure that is able to convey all necessary information.