title: Use of number needed to treat in cost-effectiveness analyses.
abstract: OBJECTIVE
  To review the use of number needed to treat (NNT) and/or number needed to harm (NNH) values to determine their relevance in helping clinicians evaluate cost-effectiveness analyses (CEAs).
  
  
  METHODS
  PubMed and EconLit were searched from 1966 to September 2012.
  
  
  METHODS
  Reviews, editorials, non-English-language articles, and articles that did not report NNT/NNH or cost-effectiveness ratios were excluded. CEA studies reporting cost per life-year gained, per quality-adjusted life-year (QALY), or other cost per effectiveness measure were included. Full texts of all included articles were reviewed for study information, including type of journal, impact factor of the journal, focus of study, data source, publication year, how NNT/NNH values were reported, and outcome measures.
  
  
  RESULTS
  A total of 188 studies were initially identified, with 69 meeting our inclusion criteria. Most were published in clinician-practice-focused journals (78.3%) while 5.8% were in policy-focused journals, and 15.9% in health-economics-focused journals. The majority (72.4%) of the articles were published in high-impact journals (impact factor >3.0). Many articles focused on either disease treatment (40.5%) or disease prevention (40.5%). Forty-eight percent reported NNT as a part of the CEA ratio per event. Most (53.6%) articles used data from literature reviews, while 24.6% used data from randomized clinical trials, and 20.3% used data from observational studies. In addition, 10% of the studies implemented modeling to perform CEA.
  
  
  CONCLUSIONS
  CEA studies sometimes include NNT ratios. Although it has several limitations, clinicians often use NNT for decision-making, so including NNT information alongside CEA findings may help clinicians better understand and apply CEA results. Further research is needed to assess how NNT/NNH might meaningfully be incorporated into CEA publications.
authors: Pharmacoeconomics, Epidemiology, Pharmaceutical Policy, and Outcomes Research program, Department of Pharmacy Practice and Administrative Sciences, College of Pharmacy, University of New Mexico, Albuquerque, NM, USA. vgarg@salud.unm.edu
authors: Vishvas
authors: V
authors: Garg
authors: Xian
authors: X
authors: Shen
authors: Yan
authors: Y
authors: Cheng
authors: James J
authors: JJ
authors: Nawarskas
authors: Dennis W
authors: DW
authors: Raisch
mesh_terms: D003362:Cost-Benefit Analysis; D004358:Drug Therapy / Q000191:economics*; D006801:Humans; D061366:Numbers Needed To Treat / Q000706:statistics & numerical data*; D019057:Quality-Adjusted Life Years