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Exploring Regional Variation In Outcomes And Follow-up After Endovascular Treatment Of Abdominal Aortic Aneurysms Among Medicare Beneficiaries
Elisa Caron, MD, Christina L. Marcaccio, MD, Mikayla Kricfalusi, BA, Siling Li, MSc, Yang Song, MSc, Robert W. Yeh, MD, Marc L. Schermerhorn, MD, Eric A. Secemsky, MD.
Beth Israel Deconess Medical Center, Waltham, Massachusetts, MA, USA.

Objective: Sex, race, and socioeconomic status are known to contribute to adverse outcomes after EVAR. However, the influence of geographic location on both outcomes and follow-up after EVAR is not well understood. Methods: All fee-for-service Medicare beneficiaries ≥66 years who underwent infrarenal EVAR for intact AAA from 2011-2019 were included. Patients were divided into cohorts based on geographic location (Northeast, Midwest, South, West). The primary outcome was the composite of late aneurysm rupture, aortic reintervention, conversion to open repair, and all-cause mortality. Cumulative incidence of the primary composite outcome was determined using Kaplan-Meier methods. Individual EVAR outcomes were also analyzed using multivariable Cox regression, and post-EVAR follow up was analyzed using Poisson regression. Results: Among 111,381 patients who underwent EVAR, 17%were from the Northeast, 18% from the Midwest, 52% from the South, and 14.2% from the West. At 9 years, the incidence of the primary outcome was 74.1% in patients in the Northeast compared with 72.9% in the Midwest, 73.3% in the South, and 70.6% in the West. After adjustment, compared with the Northeast, the incidence of the primary outcome was higher in the Midwest, but similar in the South and West (Table). When mortality was separated from the primary outcome, living in the Midwest or South was associated with lower rates of EVAR-related complications, but higher mortality (Table1).
There were also lower rates of EVAR-related office visits and AAA surveillance imaging studies in the Midwest, South, and West compared with the Northeast (Table 1). Conclusion: Regional variation in practice had a complex impact on post-EVAR outcomes. Patients residing in the Northeast had a higher rate of EVAR-related events but lower all-cause mortality while those in the Midwest and South had lower rates of EVAR-related complications but higher mortality and higher loss to follow-up. Patients in the Northeast are being followed more closely, which may allow for earlier identification of conditions necessitating reinterventions prior to major complications and therefore contribute to their lower mortality. However, greater follow-up could also be an indicator of better engagement with the health care system generally, which is known to improve outcomes.

	Midwest vs Northeast			South vs Northeast			West vs Northeast
9-year outcomes	aHR*	95%CI	p-value	aHR*	95%CI	p-value	aHR*	95%CI	p-value
Late aneurysm rupture, aortic reintervention, conversion to open repair or death	1.04	1.01,1.07	0.02	1.02	0.99,1.05	0.12	1.01	0.97,1.05	0.61
late aneurysm rupture, aortic reintervention, conversion to open repair	0.77	0.71,0.85	<.001	0.84	0.79,0.90	<.001	1	0.91,1.09	0.98
All- cause mortality	1.08	1.05,1.12	<.001	1.06	1.03,1.09	<.001	1.01	0.98,1.04	0.57
Aortic Reintervention	0.68	0.61,0.75	<.001	0.69	0.62,0.77	<.001	0.81	0.75,0.87	<.001
Conversion to Open	0.79	0.64,0.97	0.03	0.71	0.60,0.85	<.001	0.73	0.58,0.92	0.01
Late Rupture	0.62	0.52,0.75	<.001	0.69	0.60,0.79	<.001	0.81	0.67,0.97	0.02
Health Care Utilization	aRR*	95%CI	p-value	aRR*	95%CI	p-value	aRR*	95%CI	p-value
EVAR-related office visit	0.76	0.74,0.77	<.001	0.85	0.84,0.86	<.001	0.83	0.82,0.85	<.001
AAA imaging studies	0.86	0.85,0.87	<.001	0.87	0.86,0.88	<.001	0.084	0.83,0.86	<.001
*Adjusted for demographics, comorbidities, disparity measures (age, race, dual enrollment in Medicare and Medicaid, distressed community index, and rural location), and healthcare utilization; The sub distribution HR includes subjects who are event-free regardless of mortality status in the risk set. Abbreviations: CI=confidence interval, aHR=adjusted Hazard Ratio, aRR: adjusted Rate Ratio

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