A large population-based study conducted in British Columbia, Canada, has revealed that methadone is associated with a lower risk of treatment discontinuation compared to buprenorphine/naloxone in individuals undergoing treatment for opioid use disorder. The research, published in JAMA, analyzed data from over 30,000 participants initiating treatment between 2010 and 2020, a period that includes the rise of fentanyl use in North America.
The study's findings indicate that individuals receiving buprenorphine/naloxone had a significantly higher risk of discontinuing treatment within 24 months compared to those receiving methadone (88.8% vs 81.5%; adjusted hazard ratio, 1.58 [95% CI, 1.53-1.63]). This suggests that methadone may offer better treatment retention for some patients.
Mortality Rates
While treatment discontinuation rates differed, the study found that mortality rates while receiving treatment were similar between the two medications. Among incident users, mortality at 24 months was 0.08% for buprenorphine/naloxone and 0.13% for methadone (adjusted HR, 0.57 [95% CI, 0.24-1.35]). However, the researchers noted that the confidence interval for the hazard ratio was wide, indicating uncertainty in the estimate.
Study Details and Methodology
The retrospective cohort study utilized linked health administrative databases to track treatment outcomes. The researchers included incident users (first-time treatment recipients) and prevalent new users. Treatment discontinuation was defined as a period lasting ≥5 days for methadone and ≥6 days for buprenorphine/naloxone.
The study employed discrete-time survival models to estimate hazard ratios for treatment discontinuation and all-cause mortality within 24 months. Both initiator analyses (medication as assigned at initiation) and per-protocol analyses (received according to dosing guidelines) were conducted.
Implications for Clinical Practice
The results of this study have important implications for clinical practice. Given the higher risk of treatment discontinuation associated with buprenorphine/naloxone, clinicians should carefully consider individual patient needs and treatment adherence when selecting medications for opioid use disorder. Methadone may be a more suitable option for patients who struggle with adherence or who have a history of treatment failure with buprenorphine/naloxone.
Considerations and Future Research
The authors note that further research is needed to explore the factors that contribute to treatment discontinuation and to identify strategies for improving treatment retention. Additionally, future studies should examine the comparative effectiveness of buprenorphine/naloxone and methadone in different patient subgroups and in the context of evolving drug use patterns.
