Buprenorphine treatment and clinical outcomes under the opioid use disorder cascade of care.

Background: Challenges to engagement and retention on buprenorphine undermine treatment of individuals with opioid use disorder (OUD). Under the OUD Cascade of Care framework, we sought to identify patient characteristics and treatment response associated with superior clinical outcomes.

Methods: A retrospective cohort study of specialty buprenorphine treatment patients entering treatment (n=19,487) based on EHR records from a large multi-state buprenorphine treatment network (2011-2019). Person-level care episodes were evaluated across treatment intake, engagement (i.e. 2+ visits in the month following intake), and retention at 6, 12, and 24 months. Time to achieving 90 days of continuous opioid abstinence was assessed using Cox proportional hazards regressions models and also assessed as a predictor of long-term retention.

Results: Most patients engaged (82.4 %), but retention steadily declined over 6-month (38.7 %), 12-month (26.2 %), and 24-month (17.1 %) timepoints. Opioid-positive baseline tests were associated with lower hazards of achieving continuous abstinence for both buprenorphine-positive (aHR=0.33, p<.001) and buprenorphine-negative (aHR=0.49,p<.001) intakes. Opioid abstinence was associated with buprenorphine-positive baseline testing (aHR=1.59,p<.001), especially for those testing opioid-negative (aHR=1.82,p<.001). Patients who achieved and sustained abstinence at 6 months in care were 4.1 and 5.5 times as likely to achieve 12-month and 24-month retention, respectively, compared to patients with intermittent opioid use.

Conclusion: Treatment discontinuation was concentrated early in care and buprenorphine and opioid status at intake were prognostic of achieving and sustaining abstinence. Early abstinence was associated with higher likelihood of subsequent stage progression. Implementing interventions to support early clinical stability for high-risk patients is critical to improve clinical outcomes.