The Affordable Care Act Is Associated With Increased Coverage and Decreased Charges, but Limited Improvement in Access to Vascular Surgery for Medicaid Patients

Abstract

The Centers for Medicare and Medicaid Services estimate that 10 million people gained Medicaid coverage following implementation of the Patient Protection and Affordable Care Act (ACA); yet, it remains unclear how the expansion of Medicaid coverage has affected vascular surgical practice. We examined patients (18-65 years) in the National Inpatient Sample undergoing vascular procedures and total charges pre-ACA implementation (2006-2013) and post-ACA implementation (2014-October 2015). Western and Southern US census regions were surrogate exposure markers for Medicaid expansion status. International Classification of Diseases, 9th edition, procedure codes identified carotid endarterectomy, carotid artery stenting, abdominal aortic aneurysm repair (AAA) repair, endovascular AAA repair (EVAR), thoracic EVAR (TEVAR), major amputation (AMP), minor amputation (mAMP), and arteriovenous fistula/graft creation. Generalized linear models with modified Poisson distributions were calculated to compare pre- versus post-ACA outcomes, adjusted for gender and race/ethnicity. A difference-in-differences (DiD) analysis was conducted to compare post-ACA changes in vascular surgery access for Western versus Southern regions. A total of 196,684 procedures (South) and 76,031 procedures (West) were included. The proportion of uninsured patients undergoing surgery in the West decreased from 6.8% pre-ACA to 3.4% post-ACA but increased from 7.3% pre-ACA to 10.2% post-ACA in the South (P < .001). A significantly greater proportion of vascular procedures were covered by Medicaid in the West (pre-ACA 19.8% vs post-ACA 37.1%) compared to the South (pre-ACA 12.9% vs post-ACA 24.8%; P < .001; Figure). Total charges were reduced in the West (median pre-ACA $65,601 [interquartile range (IQR), $84,893], post-ACA ($55,718 [IQR, $83,950]) compared to the South (pre-ACA $44,124 [IQR, $55,079], post-ACA $39.199 [IQR, 60,142]; P < .001). In regression analyses, the post-ACA relative risk (RR) of undergoing surgery in the West versus South for Medicaid patients demonstrated a higher proportion undergoing surgery on DiD for carotid endarterectomy (adjusted RR [aRR] 2.37 [standard error, 0.05]; P < .001), mAMP (aRR, 1.17 [standard error, 0.03]; P < .001) and TEVAR (aRR, 1.35 [standard error, 0.17]; P = .008), but the RR decreased on DiD for arteriovenous fistula/graft creation (aRR, 0.49 [standard error, 0.04]; P < .001) and peripheral vascular intervention (aRR, 0.85 [standard error, 0.03]; P < .001). There were no significant differences post-ACA implementation for AAA (P = .36), carotid artery stenting (P = .49), EVAR (P = .18), lower extremity revascularization (P = .23), and AMP (P = .59) (Table). Implementation of the ACA’s Medicaid expansion was associated with significant transformation in payer mix for vascular surgery and reduction in the median charges per patient; however, improving access to limb revascularization and reducing amputations continues to lag for Medicaid patients. Future research is needed to understand the impact of Medicaid expansion on individual patient level outcomes and population health measures.TableGeneralized linear model with modified Poisson regression comparing the likelihood of a Medicaid patient undergoing a given vascular procedure in the Western versus Southern Region (referent) stratified by pre-Affordable Care Act (ACA) implementation vs post-ACA implementation and adjusted for gender and race/ethnicityWestern regionSouthern regionPre versus Post DiDP valueINTERPRETATIONAdjusted RR post-ACASEP valueAdjusted RR post-ACASEP valueAAA0.950.11.640.800.09.01.36No significant differences in AAA occurrence post-ACAAVF/AVG0.490.04<.0010.510.04<.001<.001Significantly larger decrease in AVF/AVG in the West post-ACACEA2.370.05<.0011.440.04<.001<.001Significantly greater increase in CEA in the West post-ACACAS1.350.11.0051.170.09.06.49No significant differences in CAS occurrence post-ACAEVAR3.460.13<.0014.770.09<.001.18No significant difference in the increase of EVAR post-ACALER0.970.05.461.010.03.71.23No significant differences in LER occurrence post-ACAMinor AMP1.170.03<.0010.880.03<.001<.001Significantly greater increase in minor AMP in the West post-ACAMajor AMP1.030.04.430.790.03<.001.58No significant changes in major AMP post-ACAPVI0.850.03<.0011.240.02<.001<.001PVI decreased in the West but increased in the South post-ACATEVAR1.350.17.071.450.14.009.008Significantly greater increase in TEVAR in the West post-ACAAAA, Abdominal aortic aneurysm; AMP, amputation; AVF, arteriovenous fistula; AVG, arteriovenous graft; CAS, carotid artery stenting; CEA, carotid endarterectomy; DiD, difference-in-difference; EVAR, endovascular aortic aneurysm repair; LER, lower extremity revascularization; PVI, peripheral vascular intervention; RR, relative risk; TEVAR, thoracic endovascular aortic repair.ARR of undergoing the procedure in the West compared to the South and least squares means estimates describing difference-in-differences for Medicaid patients pre- and post-ACA expansion are reported. 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