title: Incorporating external evidence in trial-based cost-effectiveness analyses: the use of resampling methods.
abstract: BACKGROUND
  Cost-effectiveness analyses (CEAs) that use patient-specific data from a randomized controlled trial (RCT) are popular, yet such CEAs are criticized because they neglect to incorporate evidence external to the trial. A popular method for quantifying uncertainty in a RCT-based CEA is the bootstrap. The objective of the present study was to further expand the bootstrap method of RCT-based CEA for the incorporation of external evidence.
  
  
  METHODS
  We utilize the Bayesian interpretation of the bootstrap and derive the distribution for the cost and effectiveness outcomes after observing the current RCT data and the external evidence. We propose simple modifications of the bootstrap for sampling from such posterior distributions.
  
  
  RESULTS
  In a proof-of-concept case study, we use data from a clinical trial and incorporate external evidence on the effect size of treatments to illustrate the method in action. Compared to the parametric models of evidence synthesis, the proposed approach requires fewer distributional assumptions, does not require explicit modeling of the relation between external evidence and outcomes of interest, and is generally easier to implement. A drawback of this approach is potential computational inefficiency compared to the parametric Bayesian methods.
  
  
  CONCLUSIONS
  The bootstrap method of RCT-based CEA can be extended to incorporate external evidence, while preserving its appealing features such as no requirement for parametric modeling of cost and effectiveness outcomes.
authors.affiliation: Institute for Heart and Lung Health, Faculty of Medicine, University of British Columbia, 317 - 2194 Health Sciences Mall (Woodward Instructional Resource Centre), Vancouver, Canada V6T 1Z3. msafavi@mail.ubc.ca.
authors.forename: Mohsen
authors.initials: M
authors.lastname: Sadatsafavi
authors.forename: Carlo
authors.initials: C
authors.lastname: Marra
authors.forename: Shawn
authors.initials: S
authors.lastname: Aaron
authors.forename: Stirling
authors.initials: S
authors.lastname: Bryan
mesh_terms: D000465:Algorithms; D001499:Bayes Theorem; D003362:Cost-Benefit Analysis / Q000191:economics / Q000379:methods; D019317:Evidence-Based Medicine / Q000191:economics* / Q000379:methods*; D006801:Humans; D016032:Randomized Controlled Trials as Topic / Q000191:economics* / Q000379:methods*; D012107:Research Design / Q000706:statistics & numerical data; D012494:Sampling Studies; D018709:Statistics, Nonparametric