Medicaid expansion and medications to treat opioid use disorder in outpatient specialty care from 2010 to 2020

Introduction

Medications for opioid use disorder (MOUD) are considered the first line treatment for opioid use disorder. As states expanded Medicaid beginning in 2014 under the Affordable Care Act, policymakers and public health officials were interested in the potential for expansion to increase access to MOUD. This study examined whether there were changes in MOUD use within outpatient admissions to specialty treatment facilities in Medicaid expansion states beyond the initial expansion period.

Methods

Analyses were conducted using 2010–2020 data from the Treatment Episode Data Set – Admissions. For states that expanded Medicaid prior to 2015, a difference-in-differences analysis was conducted to evaluate whether expansion was associated with an increased proportion of MOUD treatment comparing the initial 2014–2017 period and the 2018–2020 period to 2010–2013. We then conducted a difference-in-differences analysis to examine the overall effect of Medicaid expansion on outpatient MOUD using all states that passed expansion at any point during the study period.

Results

Among outpatient treatment episodes for OUD in states that expanded Medicaid in 2014, there was a 9.5 percentage point (95 % CI: 0.7–18.2) increase in the probability of receiving MOUD during the initial expansion period from 2014 to 2017 compared to 2010–2013 period, and a 7.5 percentage point (95 % CI: −8.1 –23.1) increase in 2018–2020 (compared to the 2010–2013 period) after adjusting for individual-level covariates. After incorporating states that expanded Medicaid between 2015 and 2020, there was a 6.4 percentage point (95 % CI: −0.01–13.0) increase in the probability of receiving MOUD among individuals receiving care after expansion (compared to the pre-expansion period). During the study period, there was variability among states in the change in probability of receiving MOUD from prior to after Medicaid expansion from an almost 30 percentage point increase in New York to an almost 20 percentage point decrease in Washington, DC.

Conclusions

Medicaid expansion increased the probability of receiving MOUD in outpatient settings across states from initial expansion through 2020. However, these results were not statistically significant. Additionally, significant variability between states warrants further study and suggests that improving access to MOUD will require additional state and local strategies.