[Number needed to treat (NNT)-- misleading, misunderstood, misused?].
Number needed to treat (NNT) is one of several effect measures that does not capture the time dimension because it is based on observations at a given, random point in time. This aspect makes NNT a problematical measure of the effect of interventions against chronic disease processes in which time to event is an essential issue. Additionally, the statistical properties of NNT are not favorable. It may leave the impression that adverse disease events are completely avoided by intervention when in fact they are postponed. We suggest that NNT should be used and interpreted with caution.
Wisløff
Torbjørn
T
Nasjonalt kunnskapssenter for helsetjenesten, Postboks 7004 St. Olavs plass, 0130 Oslo. torbjorn.wisloff@kunnskapssenteret.no
Halvorsen
Peder A
PA
Kristiansen
Ivar Sønbø
IS
D002908:Chronic Disease / Q000628:therapy; D015510:Clinical Medicine; D016001:Confidence Intervals; D003627:Data Interpretation, Statistical; D003657:Decision Making; D006801:Humans; D018570:Risk Assessment; D018401:Sample Size; D016896:Treatment Outcome