Emerging Patterns of Substance Use and Buprenorphine Nonadherence

Abstract Emerging Patterns of Substance Use and Buprenorphine Nonadherence Kaitlin A Zinsli Chair of the Supervisory Committee: Brandon Guthrie Department of Epidemiology Opioid overdose deaths are the leading cause of accidental death in the United States, most of which consist of opioids such as fentanyl. In the midst of this crisis, we are also experiencing a related increase in people with opioid use disorder (OUD), of which many are interested in seeking treatment. Paralleling these public health issues, use of illicit substances such as cocaine, fentanyl, heroin, methamphetamine and xylazine have also seen significant rises in use and co-use, while overdoses involving more than one substance have also increased. These interrelated concerns raise questions across many different areas of public health and clinical practice. Thinking about primary prevention, one question we may ask is how we can improve monitoring of substance use and co-use in order to be aware of emerging novel substances. This information would allow us to better engage with people who use drugs (PWUD) by providing them with useful educational information and harm reduction resources tailored to the substances in their local drug supply. Beyond primary prevention, we can ask how to better understand and aid PWUD who are interested in using harm reduction and in seeking treatment for substance use disorders. To begin to answer some of these questions, we leveraged three different datasets among populations of PWUD. We first conducted an exploratory secondary analysis of data using the Project Needle Exchange Utilization Survey (NEXUS) to look at the prevalence of cocaine, fentanyl, heroin, methamphetamine and xylazine at six different syringe service programs using a novel dried blood spot (DBS) assay. We found that methamphetamine use was more prevalent in the Western U.S. whereas cocaine use was higher in the Eastern U.S. Xylazine and fentanyl were predominantly found on the East Coast. Using DBS assays may be an effective method for public health monitoring of substance use that can be used to tailor interventions and educational materials regarding substances that are commonly used locally. Secondly, we leveraged data from a two-site pilot randomized trial of a behavioral mHealth intervention called the Trial of Adherence Application for Buprenorphine Treatment (TAAB) to evaluate the association between methamphetamine use and buprenorphine adherence among people receiving buprenorphine as treatment for OUD. Among this study population, we found a significant positive association between methamphetamine use and buprenorphine non-adherence (OR: 2.56; 95% CI: 1.37-4.76). Future research and treatment program design should consider potential differences in treatment experiences of people who use methamphetamine intermittently versus those who use frequently and regularly. As adherence and retention are already challenging, it is important to ensure that we understand the profiles of drug use that are associated with increased barriers to positive treatment outcomes. Only by fully understanding this can we begin to ensure the development of individualized treatment solutions for every patient and their needs. Finally, we used data from the Rural Opioid Initiative (ROI) to described unadjusted differences in the prevalence of demographic and behavioral characteristics comparing those who reported sublingual buprenorphine injection to those who did not in the past 30 days. We also analyzed qualitative one-on-one interview data to further elucidate the context of this behavior. Buprenorphine injection was relatively common, and PWUD who injected buprenorphine more commonly reported sex- and drug-related risk behaviors for HCV and other bloodborne viruses. The finding that buprenorphine injection is a common occurrence in rural U.S. settings reinforces the need to integrate harm reduction activities into addiction treatment programs. While these findings address different questions in the general field of substance use, increasing harm reduction and decreasing overdose are the motivation behind all of them. The high burden of both OUD and overdose deaths necessitates an immediate investment in research to better understand demographic, behavioral, and regional trends in substance use, as well as their impacts on treatment outcomes, to design well-informed and efficient prevention strategies. We also discuss here potential future research efforts that will hopefully continue to progress this body of work to improve health outcomes for people who use drugs and people with OUD.