Gaps in preoperative surveillance and rupture of abdominal aortic aneurysms among Medicare beneficiaries.
OBJECTIVE
Screening and surveillance are recommended in the management of small abdominal aortic aneurysms (AAAs). Gaps in surveillance after early diagnosis may lead to unrecognized AAA growth, rupture, and death. This study investigates the frequency and predictors of rupture of previously diagnosed AAAs.


METHODS
Data were extracted from Medicare claims for patients who underwent AAA repair between 2006 and 2009. Relevant preoperative abdominal imaging exams were tabulated up to 5 years prior to AAA repair. Repair for ruptured AAAs was compared with repair for intact AAAs for those with an early diagnosis of an AAA, defined as having received imaging at least 6 months prior to surgery. Gaps in surveillance were defined as no image within 1 year of surgery or no imaging for more than a 2-year time span after the initial image. Logistic regression was used to examine independent predictors of rupture despite early diagnosis.


RESULTS
A total of 9298 patients had repair after early diagnosis, with rupture occurring in 441 (4.7%). Those with ruptured AAAs were older (80.2 ± 6.9 vs 77.6 ± 6.2 years; P < .001), received fewer images prior to repair (5.7 ± 4.1 vs 6.5 ± 3.5; P = .001), were less likely to be treated in a high-volume hospital (45.4% vs 59.5%; P < .001), and were more likely to have had gaps in surveillance (47.4% vs 11.8%; P < .001) compared with those receiving repair for intact AAAs. After adjusting for medical comorbidities, gaps in surveillance remained the largest predictor of rupture in a multivariate analysis (odds ratio, 5.82; 95% confidence interval, 4.64-7.31; P < .001).


CONCLUSIONS
Despite previous diagnosis of AAA, many patients experience rupture prior to repair. Improved mechanisms for surveillance are needed to prevent rupture and ensure timely repair for patients with AAAs.
Division of Vascular Surgery, Stanford University School of Medicine, Stanford, Calif. Electronic address: mwmell@stanford.edu.
Matthew W
MW
Mell
Department of Health Research and Policy, Stanford University School of Medicine, Stanford, Calif; National Bureau of Economic Research, Cambridge, Mass.
Laurence C
LC
Baker
Division of Vascular Surgery, Stanford University School of Medicine, Stanford, Calif.
Ronald L
RL
Dalman
Department of Health Research and Policy, Stanford University School of Medicine, Stanford, Calif; Department of Medicine, Stanford University School of Medicine, Stanford, Calif.
Mark A
MA
Hlatky
D000368:Aged; D000369:Aged, 80 and over; D017544:Aortic Aneurysm, Abdominal / Q000150:complications / Q000175:diagnosis* / Q000601:surgery; D001019:Aortic Rupture / Q000175:diagnosis* / Q000209:etiology / Q000601:surgery; D001027:Aortography; D016009:Chi-Square Distribution; D003952:Diagnostic Imaging / Q000379:methods; D018450:Disease Progression; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D016015:Logistic Models; D018810:Magnetic Resonance Angiography; D008297:Male; D006278:Medicare; D015999:Multivariate Analysis; D016017:Odds Ratio; D011237:Predictive Value of Tests; D012307:Risk Factors; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D014481:United States; D014656:Vascular Surgical Procedures; D057832:Watchful Waiting