Association of State Medicaid Expansion With Rate of Uninsured Hospitalizations for Major Cardiovascular Events, 2009-2014.

Abstract

Cardiovascular disease is the leading primary diagnosis among all hospital discharges, and insurance status is associated with patient outcomes. The association of state-level policy decisions regarding the Affordable Care Act (ACA) Medicaid expansion with rates of uninsured hospitalizations for major cardiovascular events and in-hospital mortality has not been investigated to date. To investigate whether the rates of uninsured hospitalizations for major cardiovascular events and in-hospital mortality varied by state-level policy on ACA Medicaid expansion. For this cohort study, difference-in-differences analysis of data from the Healthcare Cost and Utilization Project State Inpatient Databases of 30 US states on 524 848 non-Medicare hospitalizations in 2014 and a mean of 516 811 non-Medicare hospitalizations per year from 2009 to 2013 was performed for major cardiovascular events (defined as a composite of acute myocardial infarction, stroke, and heart failure) from January 1, 2009, through December 31, 2014. Analyses were completed September 1, 2017. State Medicaid expansion as of January 1, 2014. Comparison of mean payer mix proportions (uninsured, Medicaid, and privately insured) and in-hospital mortality between expansion and nonexpansion states for the years preceding the ACA Medicaid expansion (2009-2013) and the year after the ACA Medicaid expansion (2014). Of the 801 819 hospitalizations in the 17 expansion states in 2014, 428 503 (53.4%) patients were men, 514 036 (64.1%) were white, and 365 797 (45.6%) were aged 65 to 84 years. Of 719 459 hospitalizations in the 13 nonexpansion states in 2014, 383 311 (53.3%) patients were men, 492 136 (68.4%) were white, and 335 781 (46.7%) were aged 65 to 84 years. There were 281 184 non-Medicare hospitalizations for major cardiovascular events in the 17 expansion states and 243 664 non-Medicare hospitalizations in the 13 nonexpansion states in 2014. In multivariable regression analyses, the expansion states had a significant 5.8-percentage point decrease in the proportion of uninsured hospitalizations after Medicaid expansion relative to the nonexpansion states (adjusted difference-in-differences estimate, -0.058; 95% CI, -0.075 to -0.042; P < .001). The expansion states also had a significant 8.4-percentage point increase in the Medicaid share after Medicaid expansion relative to the nonexpansion states (adjusted difference-in-differences estimate, 0.084; 95% CI, 0.065 to 0.102; P < .001). In-hospital mortality did not change significantly after Medicaid expansion in either the expansion states (before ACA, 3.8% vs after ACA, 3.7%) or the nonexpansion states (4.0% vs 4.0%). States that expanded Medicaid during the ACA implementation had a significantly greater reduction in the proportion of uninsured hospitalizations for major cardiovascular events compared with the nonexpansion states. This study suggests that expansion status was not associated with in-hospital mortality rates in the first year after ACA implementation.