Concurrent Use of Extra‐Medical Medication for Opioid Use Disorder Among Adults Prescribed Methadone or Buprenorphine: A Cohort Study of Urban Adults Who Have Injected Drugs

INTRODUCTION: In a policy environment with constrained access to the medications for opioid use disorder (MOUD), we examined the prevalence and correlates of extra-medical use of these medications among individuals already prescribed MOUD. METHODS: Among 641 adults in Baltimore participating in the ALIVE cohort study, who self-reported buprenorphine or methadone treatment, we estimated the prevalence of using these same medications outside a formal treatment context ("extra-medical MOUD"). Using logistic regression with generalised estimating equations to account for clustering within individuals, we assess behavioural, sociodemographic, and clinical correlates of extra-medical MOUD use in this population. RESULTS: Across 1325 visits in January 2023-December 2024 (73% aged ≥ 50 years, 68% Black, 64% male), 129 (10%) reported use of extra-medical MOUD. Use of multiple substances (OR 6.05 [95% CI 3.96, 9.23]), injection drug use (6.79 [4.30, 10.70]), any withdrawal sickness (5.51 [3.62, 8.38]) and depressive symptoms (3.90 [2.64, 5.76]) were significantly associated with extra-medical MOUD use. Those engaged in methadone treatment ≥ 6 months had significantly lower odds of extra-medical use (adjusted OR [aOR]: 0.42 [0.22, 0.80]), compared with those newly engaged. By contrast, prescribed buprenorphine dose, but not duration of engagement, was associated with extra-medical use. DISCUSSION AND CONCLUSIONS: Among adults receiving legally prescribed or dispensed buprenorphine or methadone, extra-medical use of these same medications was reported at one in every 10 visits. Those with heightened vulnerability to drug-related harms were most likely to use extra-medical MOUD. Findings have implications for policies and practices restricting treatment access.