title: Comparing medications in a therapeutic area using an NNT model.
abstract: OBJECTIVE
  Clinicians are told to use the number needed to treat (NNT) to compare the benefits of therapeutic strategies, and researchers are asked to report results this way, generally without considering differences among the studies from which these were derived.
  
  
  METHODS
  The crude NNT currently advocated is compared to the NNT standardized for a common outcome, follow-up time, study population and comparator. An NNT model for cardiovascular disease is described as an example that addresses differences among studies of secondary prevention of cardiovascular disease. Crude NNTs are compared to those obtained from the model.
  
  
  RESULTS
  Follow-up in the 18 trials identified varied from 1.0 to 6.2 years; rates of cardiovascular events in the untreated subgroups ranged from 4.8% to 45.9%. The crude NNTs were more variable (9.1-163.7) than those obtained from the model (9.1-75.2). The effect of standardization was substantial in some cases, with proportional changes ranging from a 91% decrease to a 223% increase.
  
  
  CONCLUSIONS
  Using an NNT model to account for differences in study design allows for more meaningful comparisons.
authors.affiliation: Caro Research Institute, Concord, MA 01742, USA. jcaro@caroresearch.com
authors.forename: J Jaime
authors.initials: JJ
authors.lastname: Caro
authors.forename: K Jack
authors.initials: KJ
authors.lastname: Ishak
authors.forename: Ingrid
authors.initials: I
authors.lastname: Caro
authors.forename: Kristen
authors.initials: K
authors.lastname: Migliaccio-Walle
authors.forename: Wendy S
authors.initials: WS
authors.lastname: Klittich
mesh_terms: D002318:Cardiovascular Diseases / Q000188:drug therapy*; D002986:Clinical Trials as Topic; D006801:Humans; D018803:Models, Economic; D017063:Outcome Assessment, Health Care; D004364:Pharmaceutical Preparations / Q000191:economics*; D018401:Sample Size
chemical_list: D004364:Pharmaceutical Preparations