A Ten-Year before–after Study on the Impact of the Affordable Care Act Health Insurance Expansion on Emergency Department Visits in California, U.S.

Abstract

The Affordable Care Act (ACA) implemented in the U.S. aimed to improve healthcare access by expanding insurance coverage. To study the impact of ACA on Emergency Departments (Eds), we conducted a multi-center observational retrospective study of ED visits from all nonfederal acute care hospitals in California over a 10-year period (2009 and 2018), 5 years before and after ACA implementation. Primary outcome measures included total ED visits, health insurance, disposition, and diagnoses, including ambulatory-care-sensitive conditions (ACSCs), and were analyzed each year to assess for trends during the 10-year study period. Overall, ED visits increased from 8,475,330 (30,791/100,000 population) in 2009 to 11,389,384 in 2018 (37,255/100,000 population), an increase of 21.0%, with the largest increase in 2014, the first year of ACA. The payer mix also dramatically changed, with a significant drop in uninsured patient visits (21.5% to 7.8%) and an increase in government-funded Medicaid visits (18.9% to 35.7%). There was a slight decrease in visits resulting in hospitalization or transfer (21.2% to 18.1% of all D visits) and ASCS visits (173.2 to 144.3 per 1000 ED visits). In conclusion, ED visits increased significantly in California following ACA, with a decrease in uninsured patients and small decreases in both hospitalizations/transfers.