Opioid Misuse as a Predictor of Alcohol Treatment Outcomes in the COMBINE Study: Mediation by Medication Adherence.

Background: Alcohol is often consumed with opioids and alcohol misuse interferes with treatment for opioid use disorder (OUD). Drug misuse is associated with worse alcohol use disorder (AUD) treatment outcomes, yet no studies have investigated the role of opioid misuse in AUD treatment outcomes.

Methods: We conducted secondary analyses of the medication conditions of the COMBINE study (n = 1,226), a randomized clinical trial of medications (acamprosate and/or naltrexone) and behavioral interventions (medication management and/or behavioral intervention) for alcohol dependence. We examined associations between baseline opioid misuse and the use of cannabis and other drugs with time to first drinking day, time to first heavy drinking day, and the frequency and intensity of drinking during treatment and 1 year following treatment, based on latent profile analysis. Opioid misuse was defined as use of illicit or prescription opioids without a prescription or not as directed in the previous 6 months, in the absence of OUD. Self-reported cannabis and other drug use were also examined. Seventy individuals (5.7%) met the opioid misuse definition and 542 (44.2%) reported use of cannabis or other drugs without opioid misuse. We also examined medication adherence as a potential mediator.

Results: Baseline opioid misuse significantly predicted the time to first heavy drinking day (OR = 1.38 [95% CI: 1.13, 1.64], p = 0.001) and a higher probability of being in a heavier and more frequent drinking profile at the end of treatment (OR = 2.90 [95% CI: 1.43, 5.90], p = 0.003), and at 1 year following treatment (OR = 2.66 [95% CI: 1.26, 5.59], p = 0.01). Cannabis and other drug use also predicted outcomes. Medication adherence partially mediated the association between opioid misuse, cannabis use, other drug use, and treatment outcomes.

Conclusions: Opioid misuse and other drug use were associated with poorer AUD treatment outcomes, which was partially mediated by medication adherence. Clinicians and researchers should assess opioid misuse and other drug use in patients undergoing AUD treatment.