Association of Medicaid Expansion With 1-Year Mortality Among Patients With End-Stage Renal Disease.

Importance: The Affordable Care Act Medicaid expansion may be associated with reduced mortality, but evidence to date is limited. Patients with end-stage renal disease (ESRD) are a high-risk group that may be particularly affected by Medicaid expansion. Objective: To examine the association of Medicaid expansion with 1-year mortality among nonelderly patients with ESRD initiating dialysis. Design, Setting, and Participants: Difference-in-differences analysis of nonelderly patients initiating dialysis in Medicaid expansion and nonexpansion states from January 2011 to March 2017. Exposure: Living in a Medicaid expansion state. Main Outcomes and Measures: The primary outcome was 1-year mortality. Secondary outcomes were insurance, predialysis nephrology care, and type of vascular access for hemodialysis. Results: A total of 142 724 patients in expansion states (mean age, 50.2 years; 40.2% women) and 93 522 patients in nonexpansion states (mean age, 49.7; 42.4% women) were included. In Medicaid expansion states, 1-year mortality following dialysis initiation declined from 6.9% in the preexpansion period to 6.1% after expansion (change, -0.8 percentage points; 95% CI, -1.1 to -0.5). In nonexpansion states, mortality rates were 7.0% before expansion and 6.8% after expansion (change, -0.2 percentage points; 95% CI, -0.5 to 0.2), yielding an adjusted absolute reduction in mortality in expansion states of -0.6 percentage points (95% CI, -1.0 to -0.2). Mortality reductions were largest for black patients (-1.4 percentage points; 95% CI, -2.2, -0.7; P=.04 for interaction) and patients aged 19 to 44 years (-1.1 percentage points; 95% CI, -2.1 to -0.3; P=.01 for interaction). Expansion was associated with a 10.5-percentage-point (95% CI, 7.7-13.2) increase in Medicaid coverage at dialysis initiation, a -4.2-percentage-point (95% CI, -6.0 to -2.3) decrease in being uninsured, and a 2.3-percentage-point (95% CI, 0.6-4.1) increase in the presence of an arteriovenous fistula or graft. Changes in predialysis nephrology care were not significant. Conclusions and Relevance: Among patients with ESRD initiating dialysis, living in a state that expanded Medicaid under the Affordable Care Act was associated with lower 1-year mortality. If this association is causal, further research is needed to understand what factors may have contributed to this finding.