title: Using meta-regression analyses in addition to conventional systematic review methods to examine the variation in cost-effectiveness results - a case study.
abstract: BACKGROUND
  Systematic reviews of cost-effectiveness analyses summarize results and describe study characteristics. Variability in the study results is often explained qualitatively or based on sensitivity analyses of individual studies. However, variability due to input parameters and study characteristics (e.g., funding or study quality) is often not statistically explained. As a case study, a systematic review on the cost-effectiveness of drug-eluting stents (DES) versus bare-metal stents (BMS) using meta-regression analyses is performed to explore the usefulness of such methods compared with conventional review methods.
  
  
  METHODS
  We attempted to identify and review all modelling studies published until January 2012 that compared costs and consequences of DES versus BMS. We extracted general study information (e.g., funding), modelling methods, values of input parameters, and quality of the model using the Philips et al. checklist. Associations between study characteristics and the incremental costs and effectiveness of individual analyses were explored using regression analyses corrected for study ID.
  
  
  RESULTS
  Sixteen eligible studies were identified, with a combined total of 508 analyses. The overall quality of the models was moderate (59% ± 15%). This study showed associations (e.g., type of lesion) that were expected (based on individual studies), however the meta-regression analyses revealed also unpredicted associations: e.g., model quality was negatively associated with repeat revascularizations avoided.
  
  
  CONCLUSIONS
  Meta-regressions can be of added value, identifying significant associations that could not be identified using conventional review methods or by sensitivity analyses of individual studies. Furthermore, this study underlines the need to examine input parameters and perform a quality check of studies when interpreting the results.
authors.affiliation: Institute for Medical Technology Assessment, Erasmus University Rotterdam, Rotterdam, The Netherlands. ltburgers@gmail.com.|Institute of Health Policy & Management, Erasmus University Rotterdam, Rotterdam, The Netherlands. ltburgers@gmail.com.
authors.forename: Laura T
authors.initials: LT
authors.lastname: Burgers
authors.affiliation: Cochrane Netherlands, Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Fleur T
authors.initials: FT
authors.lastname: van de Wetering
authors.affiliation: Institute for Medical Technology Assessment, Erasmus University Rotterdam, Rotterdam, The Netherlands.|Institute of Health Policy & Management, Erasmus University Rotterdam, Rotterdam, The Netherlands.
authors.forename: Johan L
authors.initials: JL
authors.lastname: Severens
authors.affiliation: Institute for Medical Technology Assessment, Erasmus University Rotterdam, Rotterdam, The Netherlands.|Institute of Health Policy & Management, Erasmus University Rotterdam, Rotterdam, The Netherlands.
authors.forename: W Ken
authors.initials: WK
authors.lastname: Redekop
mesh_terms: D003362:Cost-Benefit Analysis / Q000706:statistics & numerical data; D054855:Drug-Eluting Stents / Q000191:economics; D012044:Regression Analysis