Trajectories of non-prescribed buprenorphine and other opioid use: A multi-trajectory latent class growth analysis.

Introduction: With the increasing use of non-prescribed buprenorphine (NPB), we need more data to identify the longitudinal patterns of NPB use. The goal of this natural history study is to characterize heterogeneity in trajectories of NPB, other opioid use, and participation in medication for opioid disorder (MOUD) treatment among a community-recruited sample of individuals with current opioid use disorder (OUD).

Methods: The study recruited a community-based sample of 357 individuals with OUD who used NPB in the past 6 months in Ohio, United States, for baseline and follow-up assessments (every 6 months for 2 years) of drug use, treatment participation, and other health and psychosocial characteristics. The study used multiple imputation to handle missing data. We used a multi-trajectory latent class growth analysis (MT-LCGA) to find salient groupings of participants based on the trajectories of NPB, other opioid use, and treatment participation.

Results: Over time, NPB use frequency declined from a mean of 14.6 % of days at baseline to 3.6 % of days at 24-month follow-up along with declines in heroin/fentanyl (56.4 % to 23.6 % of days) and non-prescribed pharmaceutical opioid (NPPO) use (11.6 % to 1.5 % of days). Participation in MOUD treatment increased from a mean of 17.0 % of days at baseline to 52.4 % of days at 24 months. MT-LCGA identified a 6-class model. All six classes showed declines in NPB use. Class 1 (28 %) was characterized by high and increasing MOUD treatment utilization. Class 2 (21 %) showed sustained high levels of heroin/fentanyl use and had the lowest levels of NPB use (2.2 % of days) at baseline. Class 3 (3 %) was characterized as the primary NPPO use group. Class 4 (5 %) transitioned from high levels of NPB use to increased MOUD treatment utilization. It had the highest levels of NPB use at baseline (average of 80.7 % of days) that decreased to an average of 12.9 % of days at 24 months. Class 5 (16 %) showed transition from high levels of heroin/fentanyl use to increased MOUD treatment utilization. Class 6 (27 %) showed decreased heroin/fentanyl use over time and low MOUD treatment utilization. Classes showed varying levels of improvement in psychosocial functioning, polydrug use, and overdose risks.

Conclusion: Overall, our findings suggest that NPB use was generally self-limiting with individuals reducing their use over time as some engage in greater utilization of MOUD treatment. A need exists for continuing improvements in MOUD treatment access and retention.