title: Meta-analysis of well-designed nonrandomized comparative studies of surgical procedures is as good as randomized controlled trials.
abstract: OBJECTIVE
  To compare the results of meta-analysis of nonrandomized comparative studies (NRCSs) of a surgical procedure with that of randomized controlled trials (RCTs), and to assess the effect of design and conduct issues in NRCSs on measured outcomes.
  
  
  METHODS
  Two meta-analyses of RCTs and NRCSs (2,512 and 6,438 procedures, respectively) of laparoscopic resection for colorectal cancer were performed according to accepted protocols, and 13 outcomes common between them were compared. Odds ratios (ORs) and 95% confidence intervals (CI) for dichotomous outcomes were assessed for the degree of overlap. Continuous outcomes were compared using cumulative weighted ratios (CWRs) and percentages for which a mean and standard deviation (SD) were calculated. The effects of design and conduct issues in the meta-analysis of NRCSs on measured morbidity rates were assessed using subgroup analysis.
  
  
  RESULTS
  The ORs of the three dichotomous outcomes overlapped widely. For the 10 continuous variables, the mean difference (SD) in the results of the two meta-analyses was only 5.6% (4.9%). Fulfillment of certain quality and conduct issues in the NRCSs determined the statistical homogeneity of the results of meta-analysis and their comparability with the "gold standard."
  
  
  CONCLUSIONS
  Meta-analysis of well-designed NRCSs of surgical procedures is probably as accurate as that of RCTs.
authors.affiliation: Faculty of Medicine, The Coffs Harbour Health Campus, The University of New South Wales, Coffs Harbour, NSW, Australia. nedabraham@optusnet.com.au
authors.forename: Ned S
authors.initials: NS
authors.lastname: Abraham
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Byrne
authors.forename: Jane M
authors.initials: JM
authors.lastname: Young
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Solomon
mesh_terms: D015179:Colorectal Neoplasms / Q000601:surgery*; D018849:Controlled Clinical Trials as Topic / Q000379:methods*; D003627:Data Interpretation, Statistical; D006801:Humans; D007432:Intraoperative Period; D010535:Laparoscopy; D015201:Meta-Analysis as Topic; D016032:Randomized Controlled Trials as Topic; D012086:Reoperation; D012107:Research Design; D016896:Treatment Outcome