Impacts of the COVID-19 pandemic on enrollment in medications for opioid use disorder (MOUD) in Vancouver, Canada: An interrupted time series analysis

•After COVID-19, enrolment in MOUD increased immediately followed by a gradual decline.•The impact of COVID-19 policies on enrolment in individual MOUD was mixed.•RMG practices may have contributed to support retention in MOUD. In anticipation of COVID-19 related disruptions to opioid use disorder (OUD) care, new provincial and federal guidance for the management of OUD and risk mitigation guidance (RMG) for prescription of pharmaceutical opioids were introduced in British Columbia, Canada, in March 2020. This study evaluated the combined impacts of the COVID-19 pandemic and counteracting OUD policies on enrollment in medications for OUD (MOUD). Using data from three cohorts of people with presumed OUD in Vancouver, we conducted an interrupted time series analysis to estimate the combined effects impact of the COVID-19 pandemic and counteracting OUD policies on the prevalence of enrollment in MOUD overall, as well as in individual MOUDs (methadone, buprenorphine/naloxone, slow-release oral morphine) between November 2018 and November 2021, controlling for pre-existing trends. In sub-analysis we considered RMG opioids together with MOUD. We included 760 participants with presumed OUD. In the post-COVID-19 period, MOUD and slow-release oral morphine prevalence rates showed an estimated immediate increase in level (+7.6%, 95% CI: 0.6%, 14.6% and 1.8%, 95% CI: 0.3%, 3.3%, respectively), followed by a decline in the monthly trend (-0.8% per month, 95% CI: −1.4%, −0.2% and −0.2% per month, 95% CI: −0.4, −0.1, respectively). There were no significant changes in the prevalence trends of enrollment in methadone, buprenorphine/naloxone, or when RMG opioids were considered together with MOUD. Despite immediate improvements in MOUD enrollment in the post-COVID-19 period, this beneficial trend reversed over time. RMG opioids appeared to have provided additional benefits to sustain retention in OUD care.