Mortality Rates in Medicaid Expansion States among Patients Initiating Dialysis

The Affordable Care Act (ACA) expanded eligibility for Medicaid to include nonelderly citizens and permanent residents with incomes below 138% of the federal poverty level in participating states. As of September 2018, Medicaid expansion had been adopted in 33 states and the District of Columbia. There are data showing an association between Medicaid expansion and improved coverage, access to care, preventive care, and self-rated health.

However, findings from research on the effect of the Medicaid expansions on physical health outcomes have been conflicting. One trial in Oregon failed to detect statistically significant 2-year changes in glycosylated hemoglobin, blood pressure, or cholesterol levels; conversely, two Massachusetts trials following the Medicaid expansion in the early 2000s and after health reform in 2006 found significant declines in morality.

Patients with end-stage renal disease (ESRD) face increased morbidity and mortality, loss of productivity, and impaired quality of life compared with the general population. Survival rates are known to be improved with access to effective predialysis care; however, many patients receive little or no nephrology care prior to dialysis initiation. Medicare provides coverage to most individuals requiring dialysis; however, coverage does not begin until the fourth month of dialysis.

Prior to Medicaid expansion, up to one-fifth of nonelderly patients did not have insurance coverage when initiating dialysis. Lacking insurance coverage is associated with inadequate access to predialysis care, underdiagnosis of diabetes and hypertension, and undertreatment of cardiovascular disease. Shailender Swaminathan, PhD, and colleagues recently conducted a difference-in-differences analysis to examine the associations of the ACA Medicaid expansions with mortality, insurance coverage, and predialysis nephrology care for patients with ESRD initiating dialysis. Results of the analysis were reported online in JAMA [doi:10.1001/jama.2018.16504].

The primary outcome was 1-year mortality; secondary outcomes included insurance status, predialysis nephrology care, and type of vascular access for hemodialysis at time of initiation of therapy.

The study population included 236,246 patients; of those, 142,724 were in expansion states and 93,522 were in nonexpansion states. Among those in the expansion states, mean age was 50.2 years, 40.2% were women, 27.4% were black, and 21.0% were Hispanic. Among participants in the nonexpansion state group, mean age was 49.7 years, 42.4% were women, 40.2% were black, and 17.8% were Hispanic.

The expansion state group was more likely to have diabetes and less likely to have hypertension as the primary cause of ESRD. The income eligibility levels for Medicaid were higher in 2013 and the rates of uninsurance for individuals 19 to 54 years of age were lower in expansion states compared with nonexpansion states. The mortality analyses were restricted to 180,044 patients who initiated dialysis prior to January 1, 2016, to identify deaths that occurred for up to 15 months following dialysis initiation.

Prior to 2014, mortality rates in expansion and nonexpansion states were similar; beginning in the first 6 months of 2014, mortality rates declined. In Medicaid expansion states, 1 -year mortality following initiation of dialysis declined from 6.9% in the pre-expansion period to 6.1% following expansion (change, –0.8 percentage points; 95% confidence interval [CI], –1.1 to –0.5). In nonexpansion states, the mortality rates declined from 7.0% before expansion to 6.8% following expansion (change, –0.2 percentage points, 95% CI, –0.5 to 0.2), resulting in an adjusted absolute reduction in mortality in expansion states of –0.6 percentage points (95% CI, –1.0 to –0.2) and a relative morality reduction of 8.5%. The difference-in-differences estimates were similar with and without multivariable adjustment.

In analyses by subgroup, adults 19 to 44 years of age experienced larger reductions in 1-year mortality (–1.1 percentage points; 95% CI, –2.1 to –0.3) compared with adults 45 to 64 years of age (–0.5 percentage points; 95% CI, –0.9 to –0.1; P=.01 for interaction). Among black patients, declines in 1-year mortality rates were larger compared with white patients (–1.4 percentage points; 95% CI, –2.2 to –0.7 vs –0.5 percentage points; 95% CI, –1.2 to 0.2; P=.04 for interaction). There were no statistically significant differences in adjusted mortality changes between Hispanic and white patients or for patients living in areas with poverty rates above versus below the median area-level poverty rate.

For the secondary end points, rates of Medicaid coverage for expansion and nonexpansion states diverged beginning in the first 6 months of 2014 when Medicaid coverage increased sharply in expansion states. There was a decline in the percentage of patients who were uninsured in both expansion and nonexpansion states; the decline was greater in the expansion states.

In expansion states, rates of initiating dialysis with an arteriovenous fistula or graft present were stable, but declined after 2014 in nonexpansion states. Following adjustment, there was an association between Medicaid expansion and a 10.5-percentage point increase in Medicaid coverage and a –4.2 percentage point decrease in being uninsured at the time of dialysis initiation (95% CI, 7.7-13.2 and –6.0 to –2.3, respectively) relative to nonexpansion states. There was a concurrent 1.0-percentage point increase in the proportion of patients receiving care from a nephrologist prior to initiation of dialysis and a 2.3-percentge point increase in initiating dialysis with a graft or fistula present (95% CI, –0.1 to 2.1 and 0.6-4.1, respectively).

Limitations to the study cited by the authors included the possibility that the findings may not be generalizable to patients with other chronic health care conditions, limiting the outcomes to two measures of nephrology care and 1-year mortality, and the lack of individual-level data on Medicaid eligibility.

“Among patients with ESRD initiating dialysis, living in a state that expanded Medicaid under the ACA 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,” the researchers said.

Takeaway Points

  1. Researchers conducted an difference-in-differences analysis of nonelderly patients who initiated dialysis in Medicaid expansion and nonexpansion states from January 2011 to March 2017 to assess the association of Medicaid expansion with 1-year mortality rates in that patient population.
  2. The primary outcome of interest was 1-year mortality; secondary end points were insurance status, predialysis nephrology care, and vascular access type for hemodialysis.
  3. Patients with end-stage renal disease who initiated dialysis in states that expanded Medicaid under the Affordable Care Act had lower 10-year mortality rates compared with those living in nonexpansion states.