"Gold-standard" medications for opioid use disorder (MOUD) treatment combines FDA-approved medications, primarily methadone and buprenorphine, with behavioral therapies to provide "whole-patient" treatment. Prior to the pandemic, methadone and buprenorphine were subject to greater federal regulations than medications for other substance use disorders, including medication for alcohol use disorder (MAUD), which created barriers to MOUD initiation and retention. These barriers were exacerbated by physical distancing and diminished clinic capacities during the COVID-19 pandemic. To prevent healthcare disruption and expand access to MOUD treatment during the public health emergency, federal and state authorities implemented several MOUD policy changes during the pandemic to reduce barriers to MOUD initiation and retention, which subsequently became permanent.

This study is an evaluation of the impacts of these policies on treatment use, retention, and patient outcomes pre- and post-MOUD policy implementation.

A mixed method study design will be implemented for this research study which has 3 specific aims.

Aim 1. Examine the long-term effects of MOUD policy changes on MOUD receipt, coverage, retention, and receipt of behavioral therapy, relative to commensurate measures among patients with AUD.

Aim 2. Examine the long-term effects of MOUD policy changes on outcomes for patients with OUD, including emergency department (ED) visits, inpatient hospitalization, substance use, relapse, and fatal and non-fatal overdoses, in contrast to pre-/post-period trends among our AUD comparison group.

Aim 3. Contextualize longitudinal results using qualitative methods to examine the impacts of MOUD policy changes from the perspectives of veteran patients with OUD, MOUD providers, and the Veteran's Health Administration Substance Use Disorder (VHA SUD) treatment leadership, and actors influencing the reach, effectiveness, adoption, implementation, and maintenance of MOUD policy changes.

For Aims 1 and 2, an observational cohort study will be conducted, using an interrupted time-series or difference-in-difference design to evaluate pre/post changes in treatment utilization and patient outcomes related to the nationwide MOUD policy changes introduced in 2020 expanding on access to MOUD treatment. The comparator for these analyses are patients with alcohol use disorder (AUD) for whom COVID-19 treatment disruptions applied but MOUD policies did not.

Data will be sourced from the Veteran's Health Administration Corporate Data Warehouse (CDW), including notes and Veteran's Administrations (VA) Mortality Data Repository and Community Care (CC) data. Aim 3 is a qualitative aim for which we will interview VA MOUD providers, VA substance use disorder treatment leadership, and VA patients with OUD.

Inclusion Criteria:

• Substance use disorder (alcohol and/or opioid) documented in the Veteran's Health Administration Corporate Data Warehouse (CDW)

Exclusion Criteria:

• None

A quasi-experimental and comparative interrupted time-series observational cohort study design will be used to compare trends across the pre- and post-MOUD policy change years, between mutually exclusive groups of patients with OUD and AUD (and no co-occurring OUD), who will be matched 1:1 on age, gender, race, rural/urban residence, and state for the pre (03/2016-02/2020) and post periods (03/2020-02/2024).