PROJECT SUMMARY / ABSTRACT: The injection drug use epidemic in the United States has also led to an epidemic of injection-related infections. Infections such as hepatitis C are increasing in incidence, especially among younger adults. Also, severe bacterial infections such as endocarditis and sepsis, which are often life-threatening, have been rising precipitously. People who use drugs are subject to stigma in the healthcare system, and evidence shows that they are less likely to be offered evidence-based treatment such as hepatitis C cure and valve surgery for endocarditis. Additionally, racial and ethnic disparities in the treatment of hepatitis C and of severe bacterial infections have also been described. Understanding how racial and ethnic disparities might manifest in people who inject drugs that are affected by injection-related infections is important to develop both individual and health-system level interventions to mitigate those disparities and provide more equitable treatment. In the parent grant, Dr. Kapadia studies HCV treatment uptake among primary care providers utilizing Medicaid claims data. This includes understanding how new treatments are being taken up by providers of different specialties and offered to patients differentially based on whether they have a substance use disorder. He also examines outcomes of HCV treatment for people treated by primary care providers compared to those treated by specialists. In this supplement, Dr. Kapadia proposes to extend the work in the parent award to examine racial and ethnic disparities for injection-related infections. This work will leverage the national Medicaid claims data he has collected for the parent award to study this critical topic. In the supplement, he will first examine racial and ethnic disparities in treatment initiation for hepatitis C, separating people who use drugs and people who do not, to see if the patterns of disparities differ. Then, he will examine racial and ethnic disparities in the treatment offered to people who inject drugs with severe bacterial infections, examine factors that may explain the pattern of disparities, and determine if these factors differ from the ones identified in patients with hepatitis C. He will use multilevel regression models to account for individual-level, hospital-level, and area- level variables that may explain the observed racial-ethnic disparities. Together, these aims will leverage the unique data sources and expertise that Dr. Kapadia is using in the parent award to answer important questions about health equity for injection-related infections. The results will be important to clinicians, public health agencies, and policymakers, and lead to interventions designed to improve health equity for these important and dangerous health conditions.