Association Between Buprenorphine Adherence Trajectories, Health Outcomes, and Health Care Costs Among Medicaid Enrollees.

Objectives: To identify distinct buprenorphine adherence trajectories among patients with opioid use disorder (OUD) and evaluate their associations with health events and health care costs.

Methods: A retrospective longitudinal cohort study was conducted using the Merative Multi-state Medicaid database. The study analyzed 12,244 Medicaid enrollees aged 18-64 years who were diagnosed with OUD and initiated buprenorphine treatment between July 1, 2017 and June 30, 2019. Group-based trajectory models were used to identify adherence patterns during the first 180 days of treatment. Cox proportional hazard models were used to evaluate the associations between adherence trajectories and time to opioid overdose, substance use disorder-related hospitalization, and all-cause hospitalization. Generalized linear models were used to compare health care costs across trajectories.

Results: Four buprenorphine adherence trajectories were identified: completely adherent (50.8%), initially adherent with later decline (13.6%), increasing adherence with later decline (9.9%), and continuously declining nonadherence (25.8%). Compared to the completely adherent group, patients in other groups had a higher risk of opioid overdose, hospitalization and increased health care costs. The continuously declining nonadherent group demonstrated the highest risks, with an opioid overdose hazard ratio (HR) of 1.92 (95% CI, 1.46-2.39), all-cause hospitalization of HR of 1.71 (95% CI: 1.58-1.85), and substance use disorder (SUD)-related hospitalization HR of 2.01 (95% CI: 1.82-2.15). Additionally, healthcare costs were notably higher compared to the completely adherent group, with an increase of $1482.45 (95% CI: $745.45-$2756.01) in the increasing adherence with later decline group and $1698.46 (95% CI: $432.57-$3087.78) in the continuously declining nonadherence groups.

Conclusions: Almost half of Medicaid beneficiaries with OUD exhibited varying degrees of nonadherence to buprenorphine within 180 days of treatment initiation. This nonadherence was associated with adverse clinical outcomes and increased health care costs. Health care providers should consider adherence challenges when designing therapeutic interventions with buprenorphine.