title: How effective is that treatment? The number needed to treat.
abstract: The Number Needed to Treat (NNT) is a tool useful for comparing the relative effectiveness of two or more therapeutic or preventive interventions. The NNT may be presented by authors of a clinical research article, or, if not provided, may be calculated by the reader if the authors have reported outcomes as positive or negative per research subject. The NNT is simply calculated as the inverse of the absolute risk reduction. The NNT is most meaningful when reported within a confidence interval and when describing clinical trials of higher validity such as randomized controlled trials and meta-analyses of such trials. Several example NNTs from the dental and medical literature are reported.
authors.affiliation: Department of Developmental Dentistry, University of Texas Health Science Center at San Antonio Dental School, San Antonio, Texas 78258, USA. deahl@uthscsa.edu
authors.forename: S Thomas
authors.initials: ST
authors.lastname: Deahl
mesh_terms: D003627:Data Interpretation, Statistical; D018865:Dental Research / Q000706:statistics & numerical data*; D055094:Evidence-Based Dentistry / Q000706:statistics & numerical data*; D006801:Humans; D016013:Likelihood Functions; D017063:Outcome Assessment, Health Care / Q000706:statistics & numerical data; D012107:Research Design / Q000706:statistics & numerical data*; D012306:Risk; D018570:Risk Assessment / Q000706:statistics & numerical data; D018401:Sample Size; D016896:Treatment Outcome