Franklyn, Alexandra Michelle2016-10-122016-10-122016-09-06https://laurentian.scholaris.ca/handle/10219/2634Opioid agonist therapy is the gold standard of care for opioid dependence. However, the efficacy of treatment may be hindered by concurrent drug use, including cocaine and benzodiazepines. This thesis examines the impact of concurrent drug use on treatment retention, and whether it is differentially impacted by geographic region. We conducted a retrospective cohort study using electronic medical records from 58 opioid agonist therapy clinics in Ontario. One-year treatment retention was the primary outcome of interest. Both baseline cocaine and benzodiazepine users experienced decreased retention rates than non-users. Patients who used concurrent drugs at higher frequencies experienced decreased retention rates compared to those who used less often. Northern and urban patients were more likely to be baseline cocaine users, and Southern urban patients were more likely to be benzodiazepine users. Both baseline and continued concurrent drug use is predictive of treatment drop out in Northern and Southern patients.enOpioid agonist therapytreatment retentionmethadonebuprenorphineruralityNorthern Ontarioconcurrent drug usebenzodiazepinesThesis