title: Meta-analysis and systematic review of the relationship between volume and outcome in abdominal aortic aneurysm surgery.
abstract: BACKGROUND
  This study investigated the volume-outcome relationship for abdominal aortic aneurysm (AAA) surgery and quantified critical volume thresholds.
  
  
  METHODS
  PubMed, EMBASE and the Cochrane library were searched for articles on the operation volume-outcome relationship in elective and ruptured AAA surgery. UK Hospital Episode Statistics data were also considered. Elective and ruptured AAA repairs were dealt with separately. The data were meta-analysed, and the odds ratios (95 per cent confidence interval) for mortality at higher- and lower-volume hospitals were compared. Volume thresholds were identified from each paper.
  
  
  RESULTS
  The analysis included 421,299 elective and 45,796 ruptured AAA operations. Significant relationships between mortality and annual volume were noted for both groups. Overall, the weighted odds ratio was 0.66 (0.65 to 0.67) for elective repair at a threshold of 43 AAAs per annum and 0.78 (0.73 to 0.82) for ruptured aneurysm repair at a threshold of 15 AAAs per annum, both in favour of high-volume institutions.
  
  
  CONCLUSIONS
  Higher annual operation volumes are associated with significantly lower mortality in both elective and ruptured AAA repair. This suggests that AAA surgery should be performed only at higher-volume centres.
authors: St George's Vascular Institute, St James' Wing, St George's Hospital, London, UK. peteholt@btinternet.com
authors: P J E
authors: PJ
authors: Holt
authors: J D
authors: JD
authors: Poloniecki
authors: D
authors: D
authors: Gerrard
authors: I M
authors: IM
authors: Loftus
authors: M M
authors: MM
authors: Thompson
mesh_terms: D017544:Aortic Aneurysm, Abdominal / Q000150:complications / Q000401:mortality / Q000601:surgery*; D001019:Aortic Rupture / Q000209:etiology / Q000401:mortality / Q000601:surgery*; D006801:Humans; D016017:Odds Ratio; D011183:Postoperative Complications / Q000401:mortality*; D012422:Rupture, Spontaneous; D016896:Treatment Outcome; D014656:Vascular Surgical Procedures / Q000401:mortality / Q000592:standards / Q000706:statistics & numerical data*