Impact of initial buprenorphine prescribing strategies on retention in care for patients with opioid use disorder - PROJECT SUMMARY / ABSTRACT Opioid overdose continues to take lives at an astounding rate, reaching a record high of 69,710 deaths in 2020. Medications for OUD such as buprenorphine reduce risk of opioid overdose mortality. While policy efforts have expanded buprenorphine treatment capacity, buprenorphine remains underutilized due to poor retention in care. Observational data from real-world settings demonstrate 180-day retention rates as low as 25-40%. Thus, the federal Overdose Prevention Strategy identifies research to improve retention as a key priority. To this end, research examining buprenorphine dosage regimens could identify strategies to improve retention. Data from trials and observational studies suggest that higher induction and maintenance dosage could improve retention. Scarce literature describes current buprenorphine dosage practices, but the data we do have suggest variable dosage practices, with many patients never achieving recommended dosage targets. Furthermore, research has demonstrated downward trends in buprenorphine dosage levels, meaning that underdosage may be growing. In this Mentored Research Career Development Award application, I propose to examine the relationship between buprenorphine dosage regimens and OUD treatment retention. Specifically, the goals of this work are to 1) describe current buprenorphine dosage practices in terms of dosage trajectories, 2) estimate the impact of two distinct buprenorphine dosage strategies on retention, and 3) estimate the population-level clinical and cost impact of improved buprenorphine dosage practices on retention and overdose for the state of Massachusetts. In parallel, I have identified three training objectives: 1) develop skills using machine learning clustering methods, 2) learn causal inference using a target trial emulation, and 3) develop simulation modeling skills. Through these training objectives, I will develop comprehensive synergistic skills in the data sciences. The research in this proposal builds directly on my prior work using pharmacy claims data to examine trends in buprenorphine receipt. This proposal leverages this prior experience to investigate the role of specific buprenorphine dosage strategies on retention. I have identified a supportive research environment and an experienced mentor team with a) content and methodologic expertise and b) extensive track records in guiding trainees to independent research careers. The strength of these resources will ensure that I gain the expertise necessary to succeed in completing the proposed scope of work and achieve my long-term goal of becoming an independent physician investigator using large data to study innovations for substance use disorder treatment. At the end of this award, I will be well-positioned to apply for an R-level award using national Medicaid data to examine a) the impact of emerging buprenorphine dosage strategies on retention as fentanyl adulteration penetrates the opioid supply, and b) disparities in buprenorphine dosage by race, ethnicity and region.