Factors impeding switching from methadone to buprenorphine in heroin users receiving methadone maintenance therapy -...

Switching from methadone to buprenorphine/naloxone remains a challenge for heroin users receiving methadone maintenance treatment (MMT). The present study aimed to investigate the predictors for failed switching from methadone to buprenorphine/naloxone among patients receiving MMT.

This 5-year retrospective study included 168 individuals (138 males and 30 females) with opioid dependence who attempted to switch from methadone to buprenorphine/naloxone at our MMT clinics in Taiwan. We excluded patients with psychiatric comorbidity and other substance use disorders except nicotine. A univariate Cox proportional hazards regression model (Cox model) was used to estimate the potential factors of subsequent failed switching, followed by a multivariate Cox model to identify significant predictors after adjusting for other covariates.

Seventy of the 168 participants (41.7%) failed switching from methadone to buprenorphine/naloxone. After forward selection in the Cox hazard regression model, a greater average dose of methadone (HR = 1.02; P = 0.01), greater maximal maintenance dose of MMT (HR = 1.02; P < 0.001), greater average dose of buprenorphine (HR = 1.10; P = 0.021), and lower average attendance rate during the three months before switching (HR = 0.09; P = 0.002) were significantly associated with failed switching.

This study with limited participants showed that dose of methadone, dose of buprenorphine, and attendance rates were significantly associated with failed switching. Clinicians should discuss with their patients about tapering the dose of methadone and improving their attendance if they want to switch from methadone to buprenorphine. Further studies are necessary to verify whether our findings generalize to other populations.