title: Radiographic monitoring of incidental abdominal aortic aneurysms: a retrospective population-based cohort study.
abstract: BACKGROUND
  An abdominal aortic aneurysm (AAA) that is identified when the abdomen is imaged for some other reason is known as an incidental AAA. No population-based studies have assessed the management of incidental AAAs. The objective of this study was to measure the completeness of radiographic monitoring of incidental AAAs by means of a population-based analysis.
  
  
  METHODS
  We linked a cohort of patients with incidental AAA (defined as a previously unidentified aortic enlargement exceeding 30 mm in diameter found in an imaging study performed for another reason) to various population-based databases. We followed the patients to elective repair or rupture of the aneurysm, death or 31 Mar. 2009. We used evidence-based monitoring guidelines to calculate the proportion of observation time during which each incidental AAA was incompletely monitored. We used negative binomial regression to determine the association of patient-related factors with this outcome.
  
  
  RESULTS
  For the period between January 1996 and September 2008, we identified 191 patients with incidental AAA (mean diameter 37.6 mm, 95% confidence interval [CI] 36.6-38.6 mm; median follow-up 4.4 [range 0.6-12.7] years). Fifty-six of these patients (29.3%) had no radiographic monitoring of the aneurysm. Overall, patients spent one-fifth of their time with incomplete monitoring of the AAA (median 19.4%, interquartile range 0.3%-44.0%). Factors independently associated with incomplete monitoring included older age (relative rate [change in proportion of time with incomplete monitoring] [RR] 1.27, 95% CI 1.10-1.47, per decade), larger size (RR 1.65, 95% CI 1.38-2.01, per 10-mm increase) and detection of the aneurysm while the patient was in hospital or the emergency department (RR 1.34, 95% CI 1.00-1.79). Comorbidities were not associated with monitoring.
  
  
  CONCLUSIONS
  Radiographic monitoring of incidental AAAs was incomplete, and almost one-third of patients underwent no monitoring at all. Incomplete monitoring did not appear to be related to patients' comorbidity.
authors.affiliation: University of Ottawa, Canada. carlv@ohri.ca
authors.forename: Carl
authors.initials: C
authors.lastname: van Walraven
authors.forename: Jenna
authors.initials: J
authors.lastname: Wong
authors.forename: Kareem
authors.initials: K
authors.lastname: Morant
authors.forename: Alison
authors.initials: A
authors.lastname: Jennings
authors.forename: Peter C
authors.initials: PC
authors.lastname: Austin
authors.forename: Prasad
authors.initials: P
authors.lastname: Jetty
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Forster
mesh_terms: D000368:Aged; D001012:Aorta, Abdominal / Q000000981:diagnostic imaging* / Q000637:transplantation; D017544:Aortic Aneurysm, Abdominal / Q000150:complications / Q000175:diagnosis / Q000453:epidemiology; D001019:Aortic Rupture / Q000453:epidemiology / Q000209:etiology; D019917:Blood Vessel Prosthesis Implantation / Q000379:methods / Q000706:statistics & numerical data; D002170:Canada / Q000453:epidemiology; D002423:Cause of Death; D016001:Confidence Intervals; D017558:Elective Surgical Procedures / Q000379:methods / Q000706:statistics & numerical data; D005260:Female; D006301:Health Services Needs and Demand; D006801:Humans; D033162:Incidental Findings; D008279:Magnetic Resonance Imaging; D008297:Male; D008991:Monitoring, Physiologic / Q000379:methods / Q000706:statistics & numerical data; D019370:Observation / Q000379:methods; D010043:Outcome and Process Assessment, Health Care; D012189:Retrospective Studies; D018570:Risk Assessment; D012720:Severity of Illness Index; D014057:Tomography, X-Ray Computed; D014463:Ultrasonography