PROJECT SUMMARY/ABSTRACT Antibiotics are one of the most prescribed classes of medications for children, yet 30-50% of all antibiotics are inappropriately prescribed or completely unnecessary. Despite the availability of nationally endorsed treatment guidelines and the expansion of antimicrobial stewardship programs, deviation from evidence-based practices occurs adding to prescribing variability. Individual provider characteristics including knowledge deficits are known to contribute to variability in antibiotic selection. However, other factors, including usability of available prescribing resources, local culture, social pressures, and the work environment likely also contribute to this variation, but have received less attention. Developing a rich understanding of sources of antibiotic prescribing variability among front-line providers can inform usability and workflow integration to maximize uptake of prescribing interventions. As mobile electronic clinical decision support (eCDS) tools have the potential to reach broad audiences and to integrate the end-users (i.e., front-line prescribers) and user environment (i.e., busy inpatient ward) they may serve as powerful tools in the dissemination of evidence-based antibiotic practices. Dr. Markham, a pediatric hospitalist physician and the candidate for this Career Development Award, together with a strong interdisciplinary mentorship team has created a 5-year career development plan which includes structured mentoring, completion of training in human factors science and the application of qualitative methods within systems analyses, implementation science, and clinical informatics. This unique combination of training activities in combination with Dr. Markham’s clinical expertise will place Dr. Markham at the forefront of eCDS tool implementation in pediatrics. Acquisition of these skills will establish a pathway for Dr. Markham to become a leader in addressing the quality and safety of pediatric hospitalizations through the development and implementation of novel eCDS tools and interventions targeting other high-priority diagnoses affecting children. Dr. Markham's training activities will be complemented by an innovative project that will facilitate practical application of these new skills. The goals of the project are to: (1) measure and understand inter- and intra- hospital antibiotic prescribing variability for children hospitalized with common infections; (2) utilize usability testing and psychometric analysis to evaluate the impact of an eCDS tool to deliver evidence-based antibiotic recommendations within simulated scenarios; and (3) perform a pilot implementation study to explore barriers and facilitators to widescale deployment of a usability informed antibiotic eCDS tool. Findings from this study will be used to prioritize infections in need of standardization of treatment, to track antibiotic standardization improvement over time, and to inform future implementation studies examining...