title: Use of non-randomised evidence alongside randomised trials in a systematic review of endovascular aneurysm repair: strengths and limitations.
abstract: OBJECTIVE
  To assess whether limitations of randomised controlled trials (RCTs) of endovascular aneurysm repair (EVAR) can be addressed by evidence from non-randomised studies.
  
  
  METHODS
  Analysis of data from a systematic review.
  
  
  METHODS
  We conducted a review of EVAR versus open repair or non-surgical management of abdominal aortic aneurysms. In addition to RCTs, we included pre-specified registries of EVAR and open repair.
  
  
  RESULTS
  The six included RCTs randomised patients in 2003 and earlier. Of the three registries included, one contributed data on a large (>8000) sample of patients treated with newer generation EVAR devices and followed up for up to 8 years. However, treatment dates of these patients overlapped with those of the RCTs. The other registries were of limited usefulness. A large (>45,000) controlled observational study published while the review was in progress broadly supported the findings of RCTs comparing EVAR with open surgery. A comparison of outcomes across all studies did not support the hypothesis that the findings of the RCTs are no longer representative of clinical practice.
  
  
  CONCLUSIONS
  Both randomised and non-randomised sources of evidence have strengths and weaknesses for assessing the effectiveness of EVAR. Further research should explore the optimum use of registry data, including patient-level analyses.
authors.affiliation: Centre for Reviews and Dissemination, University of York, Heslington, York YO10 5DD, UK. dc510@york.ac.uk
authors.forename: D
authors.initials: D
authors.lastname: Chambers
authors.forename: D
authors.initials: D
authors.lastname: Fayter
authors.forename: F
authors.initials: F
authors.lastname: Paton
authors.forename: N
authors.initials: N
authors.lastname: Woolacott
mesh_terms: D017544:Aortic Aneurysm, Abdominal / Q000401:mortality / Q000601:surgery*; D019917:Blood Vessel Prosthesis Implantation / Q000009:adverse effects / Q000401:mortality; D019317:Evidence-Based Medicine; D006801:Humans; D019060:Minimally Invasive Surgical Procedures; D016032:Randomized Controlled Trials as Topic; D012042:Registries; D018570:Risk Assessment; D016896:Treatment Outcome; D014656:Vascular Surgical Procedures / Q000009:adverse effects / Q000401:mortality