Impact of state medicaid expansion status on length of stay and in‐hospital mortality for general medicine patients at US academic medical centers

BACKGROUND Medicaid is often associated with longer hospitalizations and higher in-hospital mortality than other insurance types. OBJECTIVE To characterize the impact of state Medicaid expansion status under the Affordable Care Act (ACA) on payer mix, length of stay (LOS), and in-hospital mortality. DESIGN/SETTING/PATIENTS Retrospective cohort study of general medicine patients discharged from academic medical centers (AMCs) within the University HealthSystem Consortium from October 1, 2012 to September 30, 2015. INTERVENTION/MEASUREMENTS Hospitals were stratified according to state Medicaid expansion status. The proportion of discharges by primary payer, LOS index, and mortality index were compared between Medicaid-expansion and nonexpansion hospitals before and after ACA implementation. ACA implementation was defined as January 1, 2014, for all states except Michigan, New Hampshire, Pennsylvania, and Indiana, which had unique dates of Medicaid expansion. RESULTS We identified 3,144,488 discharges from 156 hospitals in 24 Medicaid-expansion states and Washington, DC, and 1,114,464 discharges from 55 hospitals in 14 nonexpansion states during the study period. Hospitals in Medicaid-expansion states experienced a significant 3.7% increase in Medicaid discharges (P = 0.013) and a 2.9% decrease in uninsured discharges (P < 0.001) after ACA implementation, whereas hospitals in nonexpansion states saw no significant change in payer mix. In a difference-in-differences analysis, the changes in LOS and mortality indices pre- to post-ACA implementation did not differ significantly between hospitals in Medicaid-expansion versus nonexpansion states. CONCLUSIONS The differential shift in payer mix between Medicaid-expansion and nonexpansion states under the ACA did not influence LOS or in-hospital mortality for general medicine patients at AMCs in the United States. Journal of Hospital Medicine 2016. © 2016 Society of Hospital Medicine