Trends in Hospital Utilization After Medicaid Expansion

Medicaid expansion was associated with an increase in hospitalizations funded by Medicaid. Whether this increase reflects an isolated payer shift or broader changes in case-mix among hospitalized adults remains uncertain.

Difference-in-differences analysis of discharge data from 4 states that expanded Medicaid in 2014 (Arizona, Iowa, New Jersey, and Washington) and 3 comparison states that did not (North Carolina, Nebraska, and Wisconsin).

All nonobstetric hospitalizations among patients aged 19-64 years of age admitted between January 2012 and December 2015.

Outcomes included state-level per-capita rates of insurance coverage, several markers of admission severity, and admission diagnosis.

We identified 6,516,576 patients admitted during the study period. Per-capita admissions remained consistent in expansion and nonexpansion states, though Medicaid-covered admissions increased in expansion states (274.6-403.8 per 100,000 people vs. 268.9-262.8 per 100,000; P<0.001). There were no significant differences after Medicaid expansion in hospital utilization, based on per-capita rates of patients-designated emergent, admitted via the emergency department, admitted via clinic, discharged within 1 day, or with lengths of stay ≥7 days. Similarly, there were no differences in diagnosis category at admission, admission severity, comorbidity burden, or mortality associated with Medicaid expansion (P>0.05 for all comparisons).

Medicaid expansion was associated with a shift in payers among nonelderly hospitalized adults without significant changes in case-mix or in several markers of acuity. These findings suggest that Medicaid expansion may reduce uncompensated care without shifting admissions practices or acuity among hospitalized adults.