Carnegie Mellon University
June 27, 2019

Gaining Medicaid Access May Shift Emergency Department Use To Be for More Severe Cases

By Caitlin Kizielewicz

Caitlin Kizielewicz
  • Heinz College of Information Systems and Public Policy
  • 412-554-0074

The Affordable Care Act expanded health insurance coverage, including eligibility for Medicaid, the public insurance program for low-income Americans. Under the ACA, states can decide whether to expand eligibility for Medicaid coverage. As of earlier this year, 36 states and the District of Columbia had adopted Medicaid expansion, and other states are considering whether to do so.

Against this background, a new study by researchers at Carnegie Mellon University and US Acute Care Solutions sought to determine how the nature of visits to emergency departments changed for previously uninsured patients who gained Medicaid insurance expansion under the ACA in 2014 and who went to an emergency room at least once before and once after expansion. The study found that compared with patients who remained uninsured in states where Medicaid was not expanded, these patients shifted their use of the emergency room toward conditions that required subsequent hospitalization and predominantly for illnesses not easily avoided by robust outpatient care. The study appears in the May 27 issue of Medical Care Research and Review.

"This is the first study to follow individual patients across multiple states who gained Medicaid insurance under the expansion of the ACA, and we found that they shifted their emergency department use toward visits for more severe conditions," said Rahul Ladhania, a recent Ph.D. graduate from CMU's Heinz College of Information Systems and Public Policy, who led the study. "The findings suggest that newly insured patients may have greater access to outpatient care for less severe conditions that had previously been addressed by visits to the emergency department."

The researchers sought to identify the average effect of enrollment in Medicaid after the ACA expansion went into effect on the nature of subsequent emergency department use by patients previously uninsured and who visited EDs at least once before and once after expansion. The researchers looked at data on patient visits from 30 emergency departments in Illinois, Nevada, North Carolina, Ohio, Oklahoma, Rhode Island and West Virginia from April 2013 through September 2015. Of these seven states, 19 emergency departments were in five states (Illinois, Nevada, Ohio, Rhode Island and West Virginia) that expanded Medicaid in January 2014, and 11 were in two states (North Carolina and Oklahoma) that did not expand Medicaid before the end of 2015. Visits in the facilities the researchers examined are comparable to national numbers.

Specifically, the researchers examined changes in use of emergency departments by previously uninsured 18- to 64-year-old patients who were identified as repeat users in states that expanded Medicaid eligibility and were Medicaid-insured after expansion. The authors compared these patients' change in emergency department use with that of patients who were similar in their use but remained uninsured because they lived in states that did not expand Medicaid. The study linked individual patients' visits to the same facility over time, which allowed researchers to track changes in individual patients' behavior as they went from being uninsured to having Medicaid or as they remained uninsured, depending on the state.

The study found that emergency department visits were nearly 29% more likely to result in hospital admission for the newly insured patients in expansion states, compared with those visiting emergency departments who remained uninsured in non-expansion states. Additionally, they found a 31% increase for conditions for which hospital admissions may not be avoided by robust treatment in an outpatient setting. The authors point to these findings as important for the patients studied because using the ED for less severe conditions is of particular concern.

"We find that Medicaid expansion led the newly insured to use EDs for more severe, acute conditions than they did when they were uninsured. This suggests that ending Medicaid expansion may increase the use of hospital emergency departments for less severe cases, reducing the efficiency of EDs in taking care of critically ill and injured patients — exactly what policymakers and clinicians wish to avoid," said Amelia Haviland, associate professor of statistics and health policy at Carnegie Mellon University, who co-authored the study.

The researchers said that the group targeted in their work — patients who use emergency departments at least twice in a two-and-a-half-year period — is a selective cohort that is a group of particular interest to policymakers.