Effects of study design and trends for EVAR versus OSR
Robert Hopkins1, James Bowen1, Kaitryn Campbell1, Gord Blackhouse4, Guy De Rose2,3, Teresa Novick2, Daria O’Reilly1,4, Ron Goeree1,4, Jean-Eric Tarride1,4
1Programs for the Assessment of Technology in Health (PATH) Research Institute, Department of Clinical Epidemiology and Biostatistics; 2Division of Vascular Surgery, Department of Surgery, London Health Sciences Centre, London, Ontario, Canada; 3Division of Vascular Surgery, Department of Surgery, Faculty of Medicine, University of Western Ontario, London, Ontario, Canada; 4Department of Clinical Epidemiology and Biostatistics, Faculty of Health Sciences, McMaster University, Hamilton, Ontario, Canada
Purpose: To investigate if study design factors such as randomization, multi-centre versus single centre evidence, institutional surgical volume, and patient selection affect the outcomes for endovascular repair (EVAR) versus open surgical repair (OSR). Finally, we investigate trends over time in EVAR versus OSR outcomes.
Methods: Search strategies for comparative studies were performed individually for: OVID’s MEDLINE, EMBASE, CINAHL, HAPI, and Evidence Based Medicine (EBM) Reviews (including Cochrane DSR, ACP Journal Club, DARE and CCTR), limited to 1990 and November 2006.
Results: Identified literature: 84 comparative studies pertaining to 57,645 patients. These include 4 randomized controlled trials (RCTs), plus 2 RCTs with long-term follow-up. The other 78 comparative studies were nonrandomized with 75 reporting perioperative outcomes, of which 16 were multi-centre, and 59 single-centre studies. Of the single-centre studies 31 were low-volume and 28 were high-volume centres. In addition, 5 studies had all patients anatomically eligible for EVAR, and 8 studies included high-risk patients only. Finally, 25 long term observational studies reported outcomes up to 3 years.
Outcomes: Lower perioperative mortality and rates of complications for EVAR versus OSR varied across study designs and patient populations. EVAR adverse outcomes have decreased in recent times.
Conclusion: EVAR highlights the problem of performing meta-analysis when the experience evolves over time.
Keywords: abdominal aortic aneurysm, endovascular repair, open surgical repair, systematic review, meta-analysis
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