Abstract
PURPOSE: Young adults are disproportionately affected by the current opioid crisis. Although medications for opioid use disorder are broadly effective, with reductions in morbidity and mortality, the particular effectiveness of medications for opioid use disorder among young adults is less well understood. METHODS: This secondary analysis compared young adults (aged 18-25 years) with older adults (aged ≥26 years) in a large comparative effectiveness trial ("XBOT") that randomized subjects to extended-release naltrexone or sublingual buprenorphine-naloxone for 6 months. Opioid relapse was defined by opioid use over four consecutive weeks or seven consecutive days, using urine testing and self-report. RESULTS: Among subjects in the intention-to-treat sample (n = 570, all randomized participants), a main effect of age group was found, with higher relapse rates among young adults (70.3%) compared with older adults (58.2%), with an odds ratio of 1.72 (95% confidence interval = 1.08-2.70), p = .02. In the per-protocol sample (n = 474, only participants who started medication), relapse rates were higher among young adults (66.3%) compared with older adults (50.8%), with an odds ratio of 1.91 (95% confidence interval = 1.19-3.06). Among the intention-to-treat sample, survival analysis revealed a significant time-by-age group interaction (p = .01) with more relapse over time in young adults. No significant interactions between age and medication group were detected. CONCLUSIONS: Young adults have increased rates of relapse compared with older adults, perhaps because of vulnerabilities that increase their risk for treatment dropout and medication nonadherence, regardless of medication assignment. These results suggest that specialized, developmentally informed interventions may be needed to improve retention and successful treatment of opioid use disorder among young adults.