Use of non-randomised evidence alongside randomised trials in a systematic review of endovascular aneurysm repair: strengths and limitations.
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.
Chambers
D
D
Centre for Reviews and Dissemination, University of York, Heslington, York YO10 5DD, UK. dc510@york.ac.uk
Fayter
D
D
Paton
F
F
Woolacott
N
N
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