Impact of Medicaid waivers on medication for opioid use disorders in residential facilities: Evidence from twenty-five states.

BACKGROUND

Medicaid Section 1115 waivers allow states to test demonstration programs with the potential to shape access to care for millions of beneficiaries. The Institutions for Mental Diseases (IMD) waiver enables states to use federal funds to treat substance use disorders in residential facilities, bypassing Medicaid's long-standing IMD exclusion. We assessed the impact of IMD waiver adoption on the use of medication for opioid use disorder (MOUD) by estimating cohort-specific effects among four groups of states that adopted waivers between 2016 and 2019.

METHODS

We used Treatment Episode Data Set data. Data on the outcome, i.e., MOUD use among opioid-involved treatment episodes, and covariates were linked to data on waiver effective date, extracted from waiver approval documents. We used difference-in-differences to estimate models stratified by treatment setting (residential vs. non-residential) and adjusted for state-level policy indicators, and state- and year-fixed effects.

RESULTS

MOUD use was low, especially among residential admissions, but increased over time from 5% in 2014-18% in 2019. In adjusted models, the cohort of states that adopted a waiver in 2016 showed higher odds of MOUD use in residential settings (OR=1.49, 95% CI: 1.21-1.84) relative to the comparison group. However, this pattern was not replicated for the later cohorts. Finally, waiver adoption did not have an impact on MOUD use in non-residential settings.

CONCLUSION

In early adopter states, IMD waivers might have facilitated MOUD use in residential facilities, but their effects varied across cohorts.