State Medicaid Expansion and Changes in Hospital Volume According to Payer

Katherine Hempstead, Joel C. Cantor

Published Year: 01/14/2016

The Affordable Care Act (ACA) has many potential implications for the hospital industry. One of the most closely followed issues is the expansion of Medicaid, which became a state option as a result of the Supreme Court decision of 2012.1 As of this writing, 31 states and Washington, D.C., have elected to expand Medicaid, and enrollment grew by 21% to more than 71 million persons between January 2014 and March 2015.2 State decisions about Medicaid expansion potentially have important implications for hospital payment sources and revenue.

A number of reports have shown a reduced volume of uninsured patients in hospitals in expansion states. However, most of these data have come from for-profit hospitals or from a single state.3,4

We performed a study using hospital-discharge data from the Hospital ACA Monitoring Project (HAMP), a voluntary surveillance effort funded by the Robert Wood Johnson Foundation.5 All state hospital associations were invited to participate by submitting quarterly data on inpatient admissions and emergency department visits according to payer. Of the 21 states currently participating, 11 have expanded Medicaid. Data submitted through HAMP are highly representative of overall hospital volume in their respective states, including, on average, 98% of acute care hospitals. States that participate in the study, as compared with nonparticipating states, have smaller Hispanic populations and lower rates of uninsurance and poverty, as shown in Table S1 in the Supplementary Appendix, available with the full text of this letter at