Medicaid Expansion After the ACA: Intensity of Treatment and Billing in Emergency Department

While emergency departments (ED) are obligated by law to treat patient regardless of ability to pay, less is known about the intensity of treatment as the patient acquires health insurance. We estimate the effect of Medicaid expansion under the Affordable Care Act (ACA) on intensity of treatment and billing in the ED using discharge data from State Emergency Department Databases (SEDD) for four states in 2013-2014. We take advantage of the visit linking feature of the data to conduct longitudinal analysis of repeat patients in the state using a difference-in-differences specification. We find that the number of procedures on discharge record increase by up to 0.2 after the expansion in expanding states, while diagnoses decline by 0.15. There is a parallel substitution from Level 3 and 4 complexity visits towards Level 5 visits in expanding states. Focusing on specific diagnostic categories, we find 1.6 percentage point (pp) decrease in ultrasounds for a patient with abdominal/pelvic symptoms, while a patient with upper respiratory symptoms is 2 pp more likely to have chest x-rays and 3 pp less likely to have an electrocardiogram in expanding states in 2014. Our results suggest, that in the presence of a fee-for-service payment system, expanding health insurance coverage leads to more intensive treatment by physicians, and billing practices that focus more intensively on revenue capture. We expand the analysis to inpatient admissions using State Inpatient Database (SID) in 2013-2014. Using the same visit linking feature, we analyze admission and re-admission rates in expanding states after the expansion.