PROJECT SUMMARY Medications for opioid use disorder (MOUD)–buprenorphine, methadone, and naltrexone–decrease illicit opioid use, increase retention in treatment, and save lives. In the United States, 2.7 million persons live with opioid use disorder and opioid-related overdose deaths totaled more than 80,000 in 2021. For patients taking MOUD, and buprenorphine in particular, the treatment of acute pain after surgery is very challenging. Patients on MOUD who use buprenorphine, as well as methadone, develop tolerance to opioid analgesics. Historically, perioperative guidelines have advocated that patients temporarily discontinue buprenorphine before surgery, out of concern that continuing buprenorphine would lead to escalation in opioid dosing and the inability to treat acute pain after surgery. However, the national conversation has recently shifted with guidelines recommending that buprenorphine, and to a lesser extent methadone, be continued in the perioperative setting. The evidence supporting this change has relied on small samples, non-surgical cohorts, and studies failing to examine relevant outcome for pain and opioid use disorder. As a result, clinicians currently operate in a clinical and policy environment with no high-quality evidence supporting these conflicting guidelines on the perioperative care for these vulnerable patients with opioid use disorder. Therefore, rigorous research on how retention to therapies of buprenorphine, as well as the two other MOUD, influences outcomes after surgery is critically needed. In this proposal, we will use several state-of-the-art national databases to achieve a better understanding of perioperative management of buprenorphine and other MOUD. In doing so, we will examine the consequences of buprenorphine therapy retention on opioid overdose risk and other relevant health outcomes among privately insured, Medicaid, and Medicare patients under perioperative conditions. We will focus primarily on buprenorphine, and also include methadone, naltrexone, and mixed MOUD use in this analysis of patients aged 15 years and above, which accounts for age groups that experience high risk for initiation of opioid use disorder (older adolescents) and rapid increases in opioid use disorder diagnoses (older adults). In Aim 1, we will delineate variation in the impact of surgery on the retention of buprenorphine and other MOUD therapies while providing the most up-to-date information on national patterns of MOUD treatment retention after surgery. These analyses will also identify factors that predict retention of treatment after surgery. In Aim 2, we will evaluate whether MOUD treatment retention after surgery is associated with postoperative opioid prescribing and clinical outcomes. In Aim 3, we will assess whether MOUD treatment retention after surgery is associated with reductions in opioid overdose events and mortality. Findings from this proposal will inform efforts to optimize the perioperative management of bu...