Abstract
BACKGROUND: It has been suggested that opioid agonist therapy (OAT) may have a secondary benefit of reducing methamphetamine/amphetamine use. However, current evidence is limited and conflicting, and little is known on the impacts of different OATs on methamphetamine/amphetamine use. The aim of this study was to examine the comparative effectiveness of buprenorphine/naloxone and methadone on methamphetamine/amphetamine use among individuals with opioid use disorder (OUD) initiating OAT in Canada. METHODS: Data for this study were derived from a 24-week pan-Canadian pragmatic trial conducted between 2017 and 2020 comparing supervised methadone versus flexible take-home dosing buprenorphine/naloxone models of care among OUD. Generalized linear mixed models were used to evaluate the independent effect of treatment (ie, methadone or buprenorphine/naloxone) and time in treatment (ie, week 2 through 24, continuous) on methamphetamine/amphetamine use (measured by urine drug test and self-report using Timeline Follow-Back). RESULTS: The sample included 210 participants that initiated OAT, of which 130 (61.9%) were using methamphetamine/amphetamine at baseline. In multivariable analysis, neither treatment nor time in treatment were significantly associated with the odds of methamphetamine/amphetamine use (adjusted odds ratio [AOR] = 0.61, 95% confidence interval [CI] = 0.34-1.08, P = .092; and AOR = 0.73, CI = 0.40-1.28, P = .283, respectively). No interaction between treatment and time in treatment was observed for methamphetamine/amphetamine use (P = .367). CONCLUSION: Methamphetamine/amphetamine use was common among this sample of people with OUD initiating OAT in Canada. Over the 24-week study period, buprenorphine/naloxone and methadone were not associated with a quantifiable change in methamphetamine/amphetamine use among this sample population. The observation of less methamphetamine/amphetamine use in the buprenorphine/naloxone arm warrants further research.