Article Title

Emergency Department Use in a U.S. Health Care System Before and After Implementation of the Coverage Provisions of the Affordable Care Act

Publication Date



ambulatory/outpatient care, health care costs/resource use, hospitals, access to services


Background: Overcrowding of hospital emergency departments (EDs) presents a major public health issue across the United States. Overcrowding has been linked to decline in quality of care and patient satisfaction, decreased revenue and increased patient mortality. In January 2014, the full implementation of the Affordable Care Act (ACA) extended health coverage to 32 million Americans. The literature has subsequently reported a post-ACA rise in ED utilization, but early analysis of two hospitals in the Sutter Health system demonstrated a delayed effect. We sought to characterize the longitudinal changes in ED utilization at 21 EDs across Sutter Health before and after ACA.

Methods: We reviewed demographic and hospital accounts data from the California Office of Statewide Health Planning and Development for all 21 Sutter Health EDs throughout Northern California. We compared utilization and examined trends over time, from 2010 to 2015. We categorized five types of trends over time as follows: NC = no change, CI = constant increasing slope, CD = constant decreasing slope, DI = delayed effect until 2014 with increase thereafter, and DD = delayed effect until 2014 with decrease thereafter.

Results: Across the system from January 2010 to December 2015, 15 (71%) EDs followed a DI pattern, 4 (19%) a CI pattern, 1 an NC pattern, and 1 was unclassified. For Medicaid patients, 15 (71%) EDs followed a DI pattern. For all hospitals, self-pay patients followed DD patterns of utilization. Use by Medicare patients primarily followed an NC pattern (n = 17, 81%). Overall utilization increased by 20% during the study period. This was driven by a 6% increase in the first 4 years, followed by 12% increase for the last 2 years of the study period.

Conclusion: ED use across the Sutter Health system increased after the implementation of the ACA. The escalation in annual ED visits was driven by a sharp increase after the expansion (full implementation). In fact, utilization increased 4 times faster in the 2 years post-full implementation than in the first 4 years of the initial implementation, and was attributable to a shift in uninsured patients (self-pay) gaining Medicaid or commercial insurance coverage. Further research is needed to determine how these changes affect costs and the possible implications for Sutter Health EDs.