A comparative study of treatment retention in opioid use disorder: Subcutaneous injectable versus sublingual buprenorphine

BACKGROUND AND AIMS: Buprenorphine treatment for opioid-use disorder (OUD) is commonly available in both sublingual tablets/films and extended-release subcutaneous injections; however, little is known about differences in patient retention between these two buprenorphine formulations. This study measured retention differences between patients who transitioned from sublingual to subcutaneous injectable buprenorphine and those who remained on sublingual buprenorphine throughout treatment, within a multi-location outpatient addiction treatment practice. DESIGN AND SETTING: This study was an observational propensity score-matched cohort study conducted at a multi-location outpatient addiction practice in Maryland, USA. PARTICIPANTS: Participants included 3609 patients receiving buprenorphine treatment for OUD between June 2019 and February 2024. MEASUREMENTS: Patient demographics, health history and urine toxicology results. The primary outcome was time-to-dropout in days. Kaplan-Meier and Cox Proportional Hazard models with propensity score matching were used to compare treatment retention between injectable and sublingual buprenorphine receipt. FINDINGS: Overall, 538 patients at the time of their first extended-release buprenorphine injection (INJ) were matched with 538 patients only receiving sublingual buprenorphine (SUB-only). In the unmatched sample, INJ patients were more likely than SUB-only patients to be female (INJ 47.2% vs SUB-only 38.7%, P < 0.001) and more likely to have at least an associate's degree (41.4% vs 33.9%, P < 0.001). After matching, patients who transitioned to INJ buprenorphine had lower retention in treatment compared with patients who remained on SUB buprenorphine. Median (95% confidence interval) time-to-dropout was 269 days (218-313) for INJ patients compared with 389 days (313-592) for SUB-only patients (stratified log-rank test = 13.6, P < 0.001). CONCLUSIONS: Among patients receiving medication treatment for opioid use disorder in an outpatient setting, those who transitioned from sublingual to subcutaneous injectable buprenorphine were at an increased risk for dropout compared with matched patients who only received sublingual buprenorphine.