Medicaid Expansion and Optimal Starts of Treatment for Incident Kidney Failure.

RATIONALE & OBJECTIVE: Beginning in 2014, some states expanded Medicaid eligibility to include additional low-income adults under the age of 65 years. Examining whether the expansion led to improvements in optimal treatment at the start of kidney failure has been understudied and was the focus of this investigation.

STUDY DESIGN: Observational cohort study.

SETTING & PARTICIPANTS: Patients aged 26-64 years represented in the US Renal Data System initiating treatment for kidney failure between 2008 and 2019.

EXPOSURE: Residence in states that did or did not expand Medicaid in 2014.

OUTCOME: An optimal start of kidney failure treatment was defined as undergoing preemptive kidney transplant, initiating home dialysis, or initiating in-center hemodialysis using an arteriovenous access.

ANALYTICAL APPROACH: Interrupted time-series analyses were implemented to evaluate the adjusted association of residence in a Medicaid-expansion state and optimal kidney failure treatment by comparing the trend in optimal kidney failure treatment starts during the preexpansion period versus the postexpansion period.

RESULTS: Before Medicaid expansion, the percentage of patients with optimal starts increased similarly in expansion and nonexpansion states. After Medicaid expansion, the percentage with optimal starts continued to increase in expansion states but decreased in nonexpansion states, resulting in a 3.9% (95% CI, 0.5%-7.2%) higher percentage with optimal starts in expansion versus nonexpansion states by 2019 (postexpansion vs preexpansion change in trend, P = 0.02). Most of the change in trend was attributable to a greater increase in use of home dialysis at initiation of kidney failure treatment in expansion versus nonexpansion states (difference of 0.29% per year; 95% CI, 0.08%-0.51%) during the postexpansion period.

LIMITATIONS: Potential for unmeasured confounding from state-level factors other than Medicaid expansion.

CONCLUSIONS: Medicaid expansion was associated with an increasing percentage of patients with incident kidney failure experiencing an optimal start to treatment, driven mostly by an increase in the use of home dialysis. Expanding Medicaid coverage may offer an opportunity to improve treatment for low-income patients initiating kidney replacement therapy.

PLAIN-LANGUAGE SUMMARY: This study examined whether the expansion of Medicaid eligibility in 2014 led to improvements in the percentage of patients receiving an optimal start to treatment for new-onset kidney failure (ie, kidney transplant before the need to start dialysis, initiation of home dialysis, or initiation of in-center hemodialysis using an arteriovenous access). We compared trends from 2008 to 2019 across US states that expanded Medicaid and those that did not. Before 2014, both groups showed a similar upward trend in optimal starts. However, after Medicaid expansion, states that expanded Medicaid continued to experience an increase in optimal starts whereas states that did not expand showed a decrease over time. Much of the difference was explained by a larger increase in the use of home dialysis in states that expanded access to Medicaid. Our findings suggest that expanding Medicaid may lead to better initial treatment for kidney failure.