title: The rupture rate of large abdominal aortic aneurysms: is this modified by anatomical suitability for endovascular repair?
abstract: BACKGROUND
  There are no precise estimates of the rate of rupture of large abdominal aortic aneurysms (AAA). There is recent suspicion that anatomic suitability for endovascular repair may be associated with a decreased risk of AAA rupture.
  
  
  METHODS
  Systematic literature review of rupture rates of AAA with initial diameter > or =5 cm in patients not considered for open repair, with stratification by size (<6.0 cm and 6.0+ cm), and gender, combined using random-effects meta-analysis. Proportional hazards regression to analyze factors (including gender, diabetes, initial AAA diameter, aneurysm neck, and sac lengths) associated with rupture in patients anatomically suitable for endovascular repair (EVAR 2 trial).
  
  
  RESULTS
  Previous studies (2 prospective, 2 retrospective, and 1 mixed) were identified for meta-analysis and patients with elective repair excluded. The pooled rupture rates was 18.2 [95% confidence interval (CI) 13.7-24.1] per 100 person-years. There was a 2.5-fold increase in rupture rates for patients with AAA of 6.0+ cm versus <6.0 cm, rupture rates = 2.54 (95% CI 1.69-3.85). The pooled rupture rates was nonsignificantly higher in women than men, rupture rates = 1.21 (95% CI 0.77-1.90). For EVAR 2 patients with 6+ cm aneurysms the rupture rates was 17.4 [95% CI 12.9-23.4] per 100 person-years significantly lower than the pooled rate from the meta-analysis, rupture rates = 27.0 [95% CI 21.1-34.7] per 100 person-years, P = 0.026. Patients with shorter neck lengths appeared to have a higher rupture rates than those with longer necks, but this was of borderline significance P = 0.10.
  
  
  CONCLUSIONS
  Rupture rates of large AAAs reported in different studies are highly variable. There is emerging evidence that patients anatomically suitable for endovascular repair have lower rupture rates.
authors.affiliation: Department of Vascular Surgery, Imperial College at Charing Cross, London, United Kingdom. j.powell@imperial.ac.uk
authors.forename: Janet T
authors.initials: JT
authors.lastname: Powell
authors.forename: Louise C
authors.initials: LC
authors.lastname: Brown
authors.forename: Roger M
authors.initials: RM
authors.lastname: Greenhalgh
authors.forename: Simon G
authors.initials: SG
authors.lastname: Thompson
mesh_terms: D017542:Aneurysm, Ruptured / Q000209:etiology / Q000473:pathology / Q000517:prevention & control*; D017544:Aortic Aneurysm, Abdominal / Q000473:pathology / Q000601:surgery*; D019917:Blood Vessel Prosthesis Implantation / Q000379:methods*; D006801:Humans; D016016:Proportional Hazards Models; D012307:Risk Factors; D016896:Treatment Outcome