Unintentional drug overdose: Is more frequent use of non-prescribed buprenorphine associated with lower risk of overdose?

Background: Unintentional drug overdoses have reached epidemic levels in the U.S. This study tests the hypothesis that people who have used non-prescribed buprenorphine more frequently in the past six months were less likely to experience a drug overdose during that same time period. Methods: Participants age 18 years or older with opioid use disorder who reported use of non-prescribed buprenorphine in the last six months were recruited from the Dayton, Ohio, area using a combination of targeted and modified respondent-driven sampling. Participants completed a structured interview, including six-month timeline follow-back, after informed consent. Logistic regression was used to test the association between (log-transformed) frequency of non-prescribed buprenorphine use and overdose in the previous six months, adjusted for confounding due to sex, homelessness, incarceration, substance use treatment, previous overdose, heroin/fentanyl injection, psychiatric comorbidity, and (log-transformed) frequencies of other (non-opioid) drug use. Results: Almost 89% of 356 participants were white, 50.3% were male, and 78.1% had high school or greater education. Over 27% (n = 98) reported experiencing an overdose in the past six months. After adjusting for confounding, greater frequency of non-prescribed buprenorphine use was significantly associated with lower risk of overdose (AOR = 0.81, 95% CI = 0.66, 0.98; p = .0286). Experiencing an overdose more than six months ago (AOR = 2.19, 95% CI = 1.24, 3.97); injection as the most common route of administration of heroin/fentanyl (AOR = 2.49, 95% CI = 1.36, 4.71); and frequency of methamphetamine use (AOR = 1.13, 95% CI = 1.02, 1.27) were strongly associated with increased risk of recent overdose in multivariable analysis. Discussion: The findings support our hypothesis that higher frequency of non-prescribed buprenorphine use is associated with lower risk of drug overdose, a potential harm reduction consequence of diversion. Improving the availability of buprenorphine though standard substance use disorder treatment, primary care, and other innovative methods is urgently needed.