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.

This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

BackgroundLow-income individuals without health insurance have limited access to health care. Medicaid expansions may reduce kidney failure incidence by improving access to chronic disease care.MethodsUsing a difference-in-differences analysis, we examined the association between Medicaid expansion status under the Affordable Care Act (ACA) and the kidney failure incidence rate among all nonelderly adults, aged 19–64 years, in the United States, from 2012 through 2018. We compared changes in kidney failure incidence in states that implemented Medicaid expansions with concurrent changes in nonexpansion states during pre-expansion, early postexpansion (years 2 and 3 postexpansion), and later postexpansion (years 4 and 5 postexpansion).ResultsThe unadjusted kidney failure incidence rate increased in the early years of the study period in both expansion and nonexpansion states before stabilizing. After adjustment for population sociodemographic characteristics, Medicaid expansion status was associated with 2.20 fewer incident cases of kidney failure per million adults per quarter in the early postexpansion period (95% CI, −3.89 to −0.51) compared with nonexpansion status, a 3.07% relative reduction (95% CI, −5.43% to −0.72%). In the later postexpansion period, Medicaid expansion status was not associated with a statistically significant change in kidney failure incidence (−0.56 cases per million per quarter; 95% CI, −2.71 to 1.58) compared with nonexpansion status and the pre-expansion time period.ConclusionsThe ACA Medicaid expansion was associated with an initial reduction in kidney failure incidence among the entire, nonelderly, adult population in the United States; but the changes did not persist in the later postexpansion period. Further study is needed to determine the long-term association between Medicaid expansion and changes in kidney failure incidence.