title: Treatments effects from randomized trials and propensity score analyses were similar in similar populations in an example from cardiac surgery.
abstract: OBJECTIVE
  Analyses comparing randomized to nonrandomized clinical trials suffer from the fact that the study populations are usually different. We aimed for a comparison of randomized clinical trials (RCTs) and propensity score (PS) analyses in similar populations.
  
  
  METHODS
  In a systematic review, we "meta-matched" RCTs and PS analyses that compared the off- and the on-pump technique in coronary artery bypass grafting. "Meta-confounders" were summarized in a "meta-propensity score" and were used for "meta-matching." We compared treatment effects between RCTs and PS analyses for 10 previously defined binary clinical outcomes in this "meta-matched" population as differences in "meta-odds ratios."
  
  
  RESULTS
  For all clinical outcomes, the estimated differences in "meta-odds ratios" were below an absolute value of 0.15, all confidence intervals included the null.
  
  
  CONCLUSIONS
  In our example, treatment effects of off-pump versus on-pump surgery from RCTs and PS analyses were very similar in a "meta-matched" population of studies, indicating that only a small remaining bias is present in PS analyses.
authors.affiliation: Institute of Medical Epidemiology, Biostatistics, and Informatics, Faculty of Medicine, University of Halle-Wittenberg, 06097 Halle (Saale), Germany. oliver.kuss@medizin.uni-halle.de
authors.forename: O
authors.initials: O
authors.lastname: Kuss
authors.forename: T
authors.initials: T
authors.lastname: Legler
authors.forename: J
authors.initials: J
authors.lastname: Börgermann
mesh_terms: D015982:Bias; D001026:Coronary Artery Bypass / Q000379:methods; D047549:Coronary Artery Bypass, Off-Pump; D006801:Humans; D057216:Propensity Score; D016032:Randomized Controlled Trials as Topic / Q000592:standards*