Trajectory classes of opioid use among individuals in a randomized controlled trial comparing extended-release naltrexone and buprenorphine-naloxone

Objectives: To advance our understanding of medication treatments for opioid use disorders (OUDs), identification of distinct subgroups and factors associated with differential treatment response is critical. We examined trajectories of opioid use for patients with OUD who were randomized to (but not in all cases inducted onto) buprenorphine-naloxone (BUP-NX) or extended-release naltrexone (XR-NTX), and identified characteristics associated with each trajectory. Methods: Growth mixture models (GMMs) were run to identify distinct trajectories of days of opioid use among a subsample of 535 individuals with OUD who participated in a 24-week randomized controlled trial (RCT; 2014-2016) of BUP-NX (n = 281) or XR-NTX (n = 254). Results: Four distinct opioid use trajectory classes were identified for BUP-NX (near abstinent/no use (59%); low use (13.2%); low use, increasing over time (15%); and moderate use, increasing over time (12.8%)). Three distinct opioid use trajectory classes were found for XR-NTX (near abstinent/no use (59.1%); low use (14.6%); and moderate use, increasing over time (26.4%)). Across both BUP-NX and XR-NTX, the near abstinent/no use class had the highest number of medical management visits. Within BUP-NX, the low use class had a greater proportion of individuals with a previous successful treatment history compared with other classes. Within XR-NTX, the moderate use, increasing over time class had the highest proportion of Hispanic participants compared with other classes. Conclusions: Findings highlight the significant heterogeneity of opioid use during a RCT of BUP-NX and XR-NTX and factors associated with opioid use patterns including medical management visits and history of treatment success.