title: The risk of rupture in untreated aneurysms: the impact of size, gender, and expansion rate.
abstract: OBJECTIVE
  The purpose of this study was to establish the risk of rupture as related to size of abdominal aortic aneurysm (AAA), gender, and expansion of the aneurysm.
  
  
  METHODS
  Between 1976 and 2001, 476 patients with conditions considered unfit for surgery with AAA 5.0 cm or more were followed with computed tomographic scans every 6 months until rupture, surgery, death, or deletion from follow-up. Surgery was performed for rupture (n = 22), improved medical condition (n = 37), increase in size (n = 95), symptoms (n = 17), and other reasons (n = 24).
  
  
  RESULTS
  Fifty ruptures occurred during the follow-up period. The average risk of rupture (and standard error) in male patients with 5.0-cm to 5.9-cm AAA was 1.0% (0.01%) per year, in female patients with 5.0-cm to 5.9-cm AAA was 3.9% (0.15%) per year, in male patients with 6.0-cm or greater AAA was 14.1% (0.18%) per year, and in female patients with 6.0-cm or greater AAA was 22.3% (0.95%) per year.
  
  
  CONCLUSIONS
  The risk of rupture in male patients with AAA 5.0 to 5.9 cm is low. The four-time higher risk of rupture in female patients with AAA 5.0 to 5.9 cm suggests a lower threshold for surgery be considered in fit women. The data regarding risk of rupture in patients with AAA 6.0 cm or more may allow more appropriate decision analysis for surgery in patients with unfit conditions with large AAA.
authors.affiliation: Department of Surgery, Queen's University, Kingston, Ontario, Canada.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Brown
authors.forename: David T
authors.initials: DT
authors.lastname: Zelt
authors.forename: Boris
authors.initials: B
authors.lastname: Sobolev
mesh_terms: D000368:Aged; D000783:Aneurysm / Q000150:complications* / Q000000981:diagnostic imaging* / Q000628:therapy; D017542:Aneurysm, Ruptured / Q000000981:diagnostic imaging* / Q000209:etiology* / Q000401:mortality; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D016017:Odds Ratio; D012044:Regression Analysis; D018570:Risk Assessment; D012307:Risk Factors; D012720:Severity of Illness Index; D012737:Sex Factors; D015996:Survival Rate; D013997:Time Factors; D014057:Tomography, X-Ray Computed