STTBI risk reduction with OAT among people with prescription-type opioid use disorder

Introduction: People who use drugs are disproportionally affected by sexually transmitted and blood borne infections (STTBIs). While the benefits of methadone in reducing injecting-risk behaviors are well-documented, less is known on its impacts on sexual-related risks, as well as its comparative effectiveness to buprenorphine/naloxone, particularly in the context of highly potent opioids. The aim of this study was to estimate the relative effects of buprenorphine/naloxone and methadone on injecting- and sexual STTBI risks among people with prescription-type opioid use disorder (POUD).  Methods: Secondary analysis of a pan-Canadian pragmatic 24-week randomized clinical trial comparing methadone and buprenorphine/naloxone models of care among 272 people with POUD (including licit or illicit opioid analgesics, fentanyl). The Risk Behavior Survey was used to collect injecting and sexual risks at baseline, week 12 and week 24.  Results: In total, 210 participants initiated treatment (103 buprenorphine/naloxone and 107 methadone). At baseline, 113/205 (55.1%) participants reported recently injecting drugs, 37/209 (17.7%) unsafe injection practices and 67/162 (41.4%) high-risk sex. Both methadone and buprenorphine/naloxone were associated with reductions in the prevalence of injection drug use and high-risk sex at week 12 and week 24 with no interactions between treatment arm and time. Conclusion: Methadone and buprenorphine/naloxone were similarly effective in reducing injecting and sexual risk behaviors among people with POUD. Clinical Trials Registration: clinicaltrials.gov NCT03033732