Distinctive trajectories of opioid use over an extended follow-up of patients in a multisite trial on buprenorphine + naloxone and methadone.
Uncovering heterogeneities in longitudinal patterns (trajectories) of opioid use among individuals with opioid use disorder can increase our understanding of disease progression and treatment responses to improve care. The present study aims to identify distinctive opioid use trajectories and factors associated with those patterns among participants randomized to treatment with methadone (MET) or buprenorphine + naloxone (BUP). Growth mixture modeling was applied to identify distinctive opioid use trajectories among 795 opioid users after their enrollment in CTN-0027 (CTN START trial), a multisite trial during 2006 to 2009, with follow-up interviews conducted during 2011 to 2014 (CTN-0050 START Follow-up trial).
Four distinctive trajectories were identified based on opioid use over the follow-up period: low use (42%), high use (22.3%), increasing use (17.1%), and decreasing use (18.6%). Greater odds of being in the high use group (relative to low use) was associated with Hispanics (relative to African American, odds ratio [OR] 3.21), injection drug use (OR 2.12), higher mental health functioning at baseline (OR 1.23), location on the West Coast (vs. East Coast, OR 2.15), and randomization to BUP (relative to MET, OR 1.53). High use and increasing use groups had greater severity in problems related to drug, employment, legal, and social/family relationships, and worsened mental health functioning at follow-up. Participation in treatment significantly accounted for both within and between-group differences in opioid use.
A very promising finding is that the largest group (more than 40% of the sample) demonstrated a consistently low level of use after entering the medication trial. In contrast, approximately 17% of the participants gradually increased their opioid use after they initially reduced use, and another 19% did not respond well initially, but gradually decreased use over time.
Conclusions: The study findings underscore the importance of keeping opioid-dependent individuals in treatment and making treatment more widely available and accessible. Identifying factors that may account for distinctive opioid use trajectory patterns can further information policy decisions and clinic practice in targeting those at greatest need for opioid treatment.
Related protocols: CTN-0027, CTN-0050