Association for Public Policy Analysis & Management

The Affordable Care Act (ACA) Medicaid expansion has substantially increased insurance coverage and access to care among low-income Americans. These increases have occurred alongside surging injuries and deaths attributable to opioids, which have quadrupled since the late 1990s. Some contend that ACA expansion have made the opioid crisis worse by increasing availability of low-cost opioid pain relievers (OPRs). However, insurance can also increase access to treatment of opioid use disorder medication, especially buprenorphine.

We examined changes in use of OPRs and buprenorphine following the ACA Medicaid expansion. We used longitudinal, patient-level, retail pharmacy claims were extracted from the IQVIA RWD anonymized longitudinal prescription database. Our main sample included 11.9 million unique individuals who filled > 2 prescriptions for a prescription opioid during at least one year between 2010-2015 from California, Maryland, and Washington (Medicaid expansion states) and Florida and Georgia (non-expansion states). We aggregated data to county-year observations (N=1,940) and linked these data to county-level covariates. For OPRs and buprenorphine we separately calculated the percent of county residents with a prescription in the year, the percentage of prescriptions paid by different sources, and mean duration of treatment. For each outcome, we estimated a difference-in-differences regression model comparing changes before and after Medicaid expansion in expansion versus non-expansion counties. Models adjusted for county demographics, uninsured rate and overdose mortality in the baseline year (2010).

In Medicaid expansion counties, rates of OPR utilization declined by 21.4% during the study period and rates of buprenorphine increased by 36.1%. In regression analysis, there was no evidence that use of buprenorphine or OPRs differed significantly between counties based on Medicaid expansion. Payment by Medicaid for OPRs increased by 7.5 percentage points (56.3% over baseline) in expansion counties relative to non-expansion counties, which was mainly offset by decreased private insurance payment. Payment by Medicaid for buprenorphine increased by 6.2 percentage points (111% over baseline) in expansion counties relative to non-expansion counties, and payment by private insurance significantly decreased. In sensitivity analysis, we find that results are robust when we look at a smaller cohort of individuals consistently observed in the data and when we drop each state and rerun the analysis.

Overall, we find that insurance expansions under the ACA did not change the prescribing rate of OPRs or buprenorphine, but Medicaid expansion was associated with a major shift in financing away from private insurance for these medications, suggesting a crowd-out effect. Findings are policy relevant: Medicaid programs play an increasingly important role in financing OPRs, which may provide opportunities to refocus pain management. For example, Maryland and Washington Medicaid now have prior authorization requirements in place for patients seeking high-dosage or long-acting opioids. Medicaid is also increasingly important in financing addiction treatment. States are also revisiting their prior authorization rules to ensure that they do not hinder access to buprenorphine, though many states continue to maintain limitations on buprenorphine prescribing in Medicaid.