Effects of access barriers and medication acceptability on buprenorphine-naloxone treatment utilization over 2 years: Results from a multisite randomized trial of adults with opioid use disorder.

BACKGROUND: Nationwide efforts seek to address the opioid epidemic by increasing access to medications for opioid use disorder (OUD), particularly with buprenorphine. A poorly understood challenge is that among individuals with OUD who do receive buprenorphine, many do not adhere to the pharmacotherapy long enough to achieve sustained benefits. We aimed to identify factors associated with buprenorphine treatment utilization over time. METHODS: We used random-intercept modeling to identify factors associated with buprenorphine treatment utilization over 2 years after first follow-up by 789 individuals with OUD who had participated in a multi-site randomized clinical trial of buprenorphine compared to methadone. Key predictors were participants' reports of buprenorphine treatment accessibility and acceptability (assessed at first follow-up) and their interaction effects, controlling for baseline randomization status, sociodemographics, and other covariates. RESULTS: Approximately 9.3-11.2% of participants utilized buprenorphine treatment over the 2 years of follow-up. Interaction effects indicated that individuals who perceived buprenorphine to be both accessible and acceptable were most likely to use buprenorphine during follow-up, controlling for other factors. In contrast, individuals who perceived buprenorphine to be unacceptable were least likely to use buprenorphine, regardless the level of perceived access to the medication. Buprenorphine treatment utilization was also negatively associated with Hispanic ethnicity, West coast context, and cumulative months receiving methadone treatment and incarceration during follow-up. CONCLUSIONS: To engage more individuals with OUD in long-term treatment with buprenorphine, interventions should target buprenorphine treatment acceptability, in addition to increasing buprenorphine access, and tailor efforts to meet the needs of vulnerable populations. TRIAL REGISTRATION: The START Follow-up Study on ClinicalTrials.gov (NCT01592461).