LAUSR

BACKGROUND Rates of non-medical use of opioids, and opioid use disorders (OUD) have been rising throughout North America. Methadone and buprenorphine/naloxone are the recommended first-line treatment options for OUD in Canada. Most studies to date have been conducted among heroin users, in controlled settings, and using similar strict dosing schedules (i.e., daily witnessed ingestion) despite buprenorphine/naloxone's superior safety profile, which allows a more flexible take-home dosing schedule. This study was designed to assess the relative effectiveness of buprenorphine/naloxone- and methadone-based models of opioid agonist therapy (OAT) for the treatment of prescription opioid use disorder (POUD) in routine clinical care. METHODS OPTIMA is a multicenter, open-label, pragmatic, randomized, two-arm, non-inferiority, 24-week study comparing the relative effectiveness of buprenorphine/naloxone (provided via flexible take-home doses) to methadone (provided via daily witnessed ingestion) models of OAT for the treatment of POUD. Approximately 276 non-pregnant adults meeting DSM-5 criteria for OUD, currently not in OAT, will be randomized across 7 Canadian sites. The primary outcome is reduction of non-medical opioid use, measured by bi-weekly urine drug screens during the 24-week study period. Secondary outcomes include treatment retention and satisfaction, safety, medication adherence, and patient engagement. DISCUSSION The OPTIMA study is the first randomized clinical trial to compare the relative effectiveness of buprenorphine/naloxone (flexible take-home doses) versus methadone (daily witnessed ingestion) models of OAT for POUD in real-world clinical settings. This study will generate urgently needed evidence towards treatment options to guide the health system response to the ongoing opioid crisis. CLINICAL TRIAL REGISTRATION NCT03033732.