PROJECT SUMMARY Febrile infants are at risk for potentially fatal invasive bacterial infections, but clinical decisions vary widely and thousands of infants may experience harms from under-testing or over-treatment. Practice variation costs up to $700 billion each year and is associated with poor outcomes, low-quality care, and inequities. However, there is a paucity of research examining the extent to which key sources contribute to practice variation, particularly for febrile infants. Addressing this gap in knowledge is an essential first step to improve the effectiveness, efficiency, and equity in care for febrile infants. Dr. Yaeger is a board-certified pediatric hospitalist whose prior research has focused on understanding how clinical and social factors can improve child health outcomes. This K23 Mentored Patient-Oriented Research Career Development Award will allow him to learn new methods to investigate sources of practice variation, understand subsequent effects, and ultimately devise interventions to reduce practice variation, improve outcomes, and decrease costs, thereby improving equity for all febrile infants. The proposed studies and career development plan will directly support the candidate's goal of becoming an independent clinician-investigator and expert in clinical decision-making and child health equity. To achieve this goal, he has assembled an inter-disciplinary mentoring team from the University of Rochester Departments of Family Medicine, Public Health Sciences, and Emergency Medicine. In addition to completing relevant coursework, workshops, longitudinal training programs, and individual didactic sessions, Dr. Yaeger will gain expertise from his team, who will guide him in achieving his Training and Career Goals. These goals include gaining expertise and skills in: 1) decision science; 2) multi-level modeling, and; 3) mixed methods. His research plan seeks to understand the extent to which disease rates, local supply of resources, clinical characteristics, parent/caregiver preferences, and local practice culture contribute to practice variation in febrile infants. The aims are: 1) To estimate practice variation and the extent to which disease rates and local resources explain practice variation; 2) To examine contextual factors associated with practice variation; 3) To investigate the effect of a national clinical practice guideline on practice variation. He will accomplish Aim 1 using a state-wide, population-based administrative dataset and small area variation analysis framework to estimate the extent to which key sources of practice variation contribute to differences in clinical decision- making. In Aim 2, he will use a mixed methods approach to identify contextual factors that may contribute to clinical decisions affecting practice variation. In Aim 3, he will investigate the extent to which a national clinical practice guideline reduces practice variation. These career development activities, mentorship, and results of these studies, provide a clear path for the candidate to secure independent funding to investigate pediatric clinical decision-making and address inequities in child health.

PROJECT NARRATIVE Emergency department clinical decisions vary widely for febrile infants, who are at risk for potentially fatal invasive bacterial infections; some infants may experience harms from under-testing or over-treatment. There is a gap in scientific knowledge regarding how clinicians make decisions for febrile infants and the extent to which key sources contribute to practice variation. Addressing this gap will provide a foundation for addressing NICHD priorities of improving care to febrile infants and promoting health equity.