title: Adherence to postoperative surveillance guidelines after endovascular aortic aneurysm repair among Medicare beneficiaries.
abstract: OBJECTIVE
  After endovascular aortic aneurysm repair (EVAR), the Society for Vascular Surgery recommends a computed tomography (CT) scan ≤30 days, followed by annual imaging. We sought to describe long-term adherence to surveillance guidelines among United States Medicare beneficiaries and determine patient and hospital factors associated with incomplete surveillance.
  
  
  METHODS
  We analyzed fee-for-service Medicare claims for patients receiving EVAR from 2002 to 2005 and collected all relevant postoperative imaging through 2011. Additional data included patient comorbidities and demographics, yearly hospital volume of abdominal aortic aneurysm repair, and Medicaid eligibility. Allowing a grace period of 3 months, complete surveillance was defined as at least one CT or ultrasound assessment every 15 months after EVAR. Incomplete surveillance was categorized as gaps for intervals >15 months between consecutive images as or lost to follow-up if >15 months elapsed after the last imaging.
  
  
  RESULTS
  Our cohort comprised 9695 patients. Median follow-up duration was 6.1 years. A CT scan ≤30 days of EVAR was performed in 3085 (31.8%) patients and ≤60 days in 60.8%. The median time to the postoperative CT was 38 days (interquartile range, 25-98 days). Complete surveillance was observed in 4169 patients (43.0%). For this group, the mean follow-up time was shorter than for those with incomplete surveillance (3.4 ± 2.74 vs 6.5 ± 2.1 years; P < .001). Among those with incomplete surveillance, follow-up became incomplete at 3.3 ± 1.9 years, with 57.6% lost to follow-up, 64.1% with gaps in follow-up (mean gap length, 760 ± 325 days), and 37.6% with both. A multivariable analysis showed incomplete surveillance was independently associated with Medicaid eligibility (hazard ratio [HR], 1.42; 95% confidence interval [CI], 1.29-1.55; P < .001), low-volume hospitals (HR, 1.12; 95% CI, 1.05-1.20; P < .001), and ruptured abdominal aortic aneurysm (HR, 1.51; 95% CI, 1.24-1.84; P < .001).
  
  
  CONCLUSIONS
  Postoperative imaging after EVAR is highly variable, and less than half of patients meet current surveillance guidelines. Additional studies are necessary to determine if variability in postoperative surveillance affects long-term outcomes.
authors.affiliation: Division of Vascular Surgery, Stanford University School of Medicine, Stanford, Calif.
authors.forename: Trit
authors.initials: T
authors.lastname: Garg
authors.affiliation: Department of Health Research and Policy, Stanford University School of Medicine, Stanford, Calif; National Bureau of Economic Research, Cambridge, Mass.
authors.forename: Laurence C
authors.initials: LC
authors.lastname: Baker
authors.affiliation: Division of Vascular Surgery, Stanford University School of Medicine, Stanford, Calif. Electronic address: mwmell@stanford.edu.
authors.forename: Matthew W
authors.initials: MW
authors.lastname: Mell
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D017544:Aortic Aneurysm, Abdominal / Q000175:diagnosis / Q000453:epidemiology / Q000601:surgery*; D001019:Aortic Rupture / Q000175:diagnosis / Q000453:epidemiology / Q000601:surgery*; D001027:Aortography; D019917:Blood Vessel Prosthesis Implantation / Q000009:adverse effects; D016009:Chi-Square Distribution; D003952:Diagnostic Imaging / Q000379:methods* / Q000592:standards; D017558:Elective Surgical Procedures; D004630:Emergencies; D057510:Endovascular Procedures / Q000009:adverse effects; D005260:Female; D019983:Guideline Adherence / Q000592:standards; D007722:Health Knowledge, Attitudes, Practice; D061847:Hospitals, High-Volume; D061846:Hospitals, Low-Volume; D006801:Humans; D007342:Insurance Benefits / Q000592:standards; D016015:Logistic Models; D008297:Male; D006278:Medicare / Q000592:standards; D015999:Multivariate Analysis; D010349:Patient Compliance; D011183:Postoperative Complications / Q000175:diagnosis* / Q000453:epidemiology; D017410:Practice Guidelines as Topic; D010818:Practice Patterns, Physicians' / Q000592:standards; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D014463:Ultrasonography; D014481:United States / Q000453:epidemiology