Association for Public Policy Analysis & Management

Despite the growing problem of opioid substance use disorders, there is a considerable gap between opioid addiction treatment needs and national and state level capacities and medication coverage nationwide. Health insurance parity regulations, like the Mental Health Parity and Addiction Equity Act of 2008 (MHPAEA), could help increase the adoption and implementation of medication assisted treatment (MAT) for substance use disorders. This type of treatment is much more dependent on public financing partly because of the decline in funding from private insurance. Given the scale of the US opioid epidemic and the potential for opioid use disorder treatments, understanding the consequences of improved access to these therapies is especially policy relevant. I use a difference-in-differences approach that exploits state-level variations of parity laws implemented before MHPAEA (such as New York and Massachusetts) to provide a credible estimate on whether the MHPAEA increased access to SUD treatment and how the costs were distributed across payers (patients and insurers). The main sources for outcome variables are the Symphony Health Pharmacy Level Claims Database, the Treatment Episode Data Set – Admissions (TEDS-A) series to look for changes in admissions to substance use disorder treatment facilities, the DEA's ARCOS data for retail drug purchases by grams at the state level, and the National Vital Statistics System (NVSS), a census of deaths in the United States. The estimates presented are MHPAEA's effect on: (a) purchased quantities of medications used to treat opioid use disorders; (b) medication assisted treatment costs and their incidence across buyers and insurers; and (c) emergency department utilization. This paper estimates that parity resulted in not just greater access but also decreased emrgency department visits relative to states who implemented parity at a later date. The medicalization of SUD treatment means that pharmacotherapy usage could be greatly expanded under the ACA, which adopted MHPAEA parity rules and mandates that individuals obtain insurance. My results provide information useful to insurance companies and policymakers at the state and federal level to better understand if parity rules were effective at increasing access without raising costs to SUD treatment. Other policies, such as mandating MATs may be a simple and cost-effective way to reduce opioid-related harms, but we have little evidence about the effects of policies governing these types of therapies. Further research may fill this critical void.