Characterising methamphetamine/amphetamine use among opioid agonist therapy‐seeking adults with prescription‐type opioid use disorder in Canada.

Introduction: There has been a significant increase in methamphetamine/amphetamine use in North America, particularly among people who use opioids. Despite its association with several negative health consequences, the population of people who use methamphetamine/amphetamine with opioids is not well characterised. The aim of this study was to investigate correlates of methamphetamine/amphetamine use among adults with prescription‐type opioid use disorder (POUD) starting methadone or buprenorphine/naloxone as part of a pragmatic randomised treatment trial in Canada. Methods: Multivariable logistic regression analyses were used to determine factors associated with baseline methamphetamine/amphetamine use (measured by urine drug test [UDT]) among participants of a pan‐Canadian pragmatic trial conducted between 2017 and 2020 comparing supervised methadone versus flexible take‐home dosing buprenorphine/naloxone models of care in people with POUD (e.g., licit or illicit, including fentanyl, prescribed or not). Results: The sample included 269 participants, of which 142 (52.8%) had positive baseline methamphetamine/amphetamine UDT. In the multivariable model, positive fentanyl UDT (adjusted odds ratio [AOR] 13.21, 95% confidence interval [CI] 6.45, 28.30), non‐fatal overdose in the last 6 months (AOR 2.26, CI 1.01, 5.17) and a lifetime history of opioid agonist therapy exposure prior to study entry (AOR 2.30, CI 1.09, 4.87) remained positively associated with baseline methamphetamine/amphetamine use. Discussion and Conclusions: In this sample of people with POUD, methamphetamine/amphetamine use was associated with markers of complex and severe OUD, including overdose risk. This suggests the need for targeted interventions to optimise treatment outcomes and prevent future overdoses in this population. Clinical Trial Registration: Available at: ClinicalTrials.gov NCT03033732. [ABSTRACT FROM AUTHOR]