Medicaid Expansion and Nephrology Care Among Incident ESRD Patients

Access to specialist human capital and its role in the efficiency and effectiveness of care is an area of ongoing debate. For patients with chronic diseases, involvement of specialists may improve outcomes, but may also consume additional resources. These facts lead physician organizations to develop guidelines for when a patient should see a specialist. Furthermore, specialists may have limited capacity for additional patients, and insurance is an important determinant of who sees specialists.

In this study we examine the role of nephrologists in the care of chronic kidney disease (CKD). The medical literature suggests that seeing a nephrologist prior to entering end stage renal disease (ESRD) produces better outcomes than waiting until ESRD. Two recent developments affecting this patient population may impact access to, and guideline-concordance of, specialist care. A large portion of the patient population with CKD have income or health characteristics that place them close to the thresholds for Medicaid coverage, and the Affordable Care Act (ACA) resulted in Medicaid expansion in 30 states between 2010- 2015. During Medicaid expansion, guidelines for pre-ESRD nephrology care changed. We examine the Medicaid expansion and change in guidelines to study the role of financing in accessing specialist care, whether those with Medicaid get differential access to guideline concordant specialist care, and the resultant short-term health impacts of access to specialists.

Using data from The United States Renal Data System from 2005-2015 we include incident ESRD patients during this period with an existing 2728 form. The outcomes of interest are source of insurance at ESRD start, receipt of appropriate pre-ESRD nephrology care, access type at first dialysis, presence of a maturing vascular access, and waitlisting at 1 year from ESRD start. We employed difference-in-difference designs, exploiting the change in Medicaid coverage and guideline change in pre-ESRD patients to examine the changes in source of insurance, guideline-concordant care, and resultant health outcomes.

Expansion led to more ESRD patients being covered by Medicaid. Expansion was not associated with increased likelihood of guideline-concordant pre-ESRD nephrology care among Medicaid recipients. Rather, the likelihood of receiving guideline-concordant care increased over time for all insured patients. The gap between Medicaid beneficiaries and other insured patients widened over the study period. The likelihood of receiving guideline-concordant nephrology care increased by 7.3, 7, and 3.2 percentage points in early, late, and non-expansion states, respectively. The likelihood of permanent access at dialysis start was not impacted by expansion, nor was the likelihood of starting dialysis with a maturing vascular access. Expansion was associated with an increase of 0.02 percentage points in the likelihood of being waitlisted within a year of ESRD start (p= 0.011).

Pre-ESRD nephrology care has increased over time, but we do not see evidence that expansion improved access to pre-ESRD care for Medicaid patients. The gap between Medicaid beneficiaries and other insured patients grew over the study period. Expansion was associated with a higher percentage of incident ESRD patients covered by Medicaid and a higher percentage of Medicaid patients being waitlisted within a year of ESRD start.