The Impact of the Affordable Care Act Insurance Expansions on Opioid‐Related Emergency Department Visits
Authors: Decker Sandra , Dworsky Michael , Gibson Teresa , Henke Rachel , McDermott Kimberly 
Published: September 2021

Research ObjectiveAmid rising opioid‐related deaths and hospital use, the 2010 Patient Protection and Affordable Care Act (ACA) was signed into law, with the central coverage provisions implemented in 2014. Because lack of health insurance is a barrier to opioid use disorder treatment, and because opioid use disorder treatment can prevent opioid‐related emergency department (ED) visits, we explore the impact of ACA Medicaid expansion and ACA marketplace insurance expansions on opioid‐related ED visits.Study DesignWe use ZIP Code‐level ED utilization data from the 2010–2018 Healthcare Cost and Utilization Project (HCUP) State Inpatient Databases (SID) and State Emergency Department Databases (SEDD) for 29 states, while also accounting for the implementation of relevant state‐level policies using information from sources such as the Kaiser Family Foundation and the Prescription Drug Abuse Policy System. We control for area‐level sociodemographic information using from sources such as the Bureau of Labor Statistics and the Census. We use a difference‐in‐differences (DD) estimation strategy as well as a within‐state dose–response, difference‐in‐differences‐in‐differences (DDD) model based on pre‐ACA uninsurance levels to estimate impacts of the ACA in each of the five years following the 2014 insurance expansions.Population StudiedWe use data on ED visits among nonelderly adults from 2010–2018 for 17 states that adopted Medicaid expansion on January 1, 2014 (Arizona, California, Connecticut, Hawaii, Illinois, Iowa, Kentucky, Maryland, Massachusetts, Minnesota, Nevada, New Jersey, New York, North Dakota, Ohio, Rhode Island, and Vermont) and 12 states that did not implement Medicaid expansion during the study period (Florida, Georgia, Kansas, Maine, Missouri, Nebraska, North Carolina, South Carolina, South Dakota, Tennessee, Utah, and Wisconsin).Principal FindingsWe find that ACA coverage expansions reduced opioid‐related ED visits, but the effect varies over time. Relative to non‐expansion states, opioid‐related ED visit rates in expansion states remain the same or decrease slightly in the first three years after Medicaid expansion (2014–2016). A more marked decline emerges in the fourth and fifth years (2017–2018) after Medicaid expansion. Both DD and DDD results show strong evidence that the impact of ACA insurance expansions on opioid‐related ED visits grew over time.ConclusionsWe find that ACA insurance expansions reduced opioid‐related ED visit rates, with an effect that grows over time. As time from ACA implementation increases, aggregate effects of lower out‐of‐pocket prices, improved access to care, and supply responses would most likely produce reductions in opioid‐related ED visits, which we find in the fourth and fifth year after ACA implementation. These dynamics help explain why studies examining shorter post‐ACA periods or that were unable to estimate time‐varying impacts did not detect significant impacts of coverage expansions on opioid‐related ED visits.Implications for Policy or PracticeThere are likely to be lags between the time when an individual with substance use disorder (or at risk of developing the disorder) gains coverage, the time when the individual accesses treatment, and consequent reductions in ED visits. Our findings suggest that there are similarly important dynamics in the impact of insurance expansion on opioid‐related ED visits.