PROJECT SUMMARY The overarching aim of this research and career development plan is for Dr. Solnick, the Principal Investigator (PI), to establish herself as an independent physician-investigator whose research focuses on advancing HIV prevention care for individuals diagnosed with sexually transmitted infections (STIs) in emergency departments (EDs). EDs have great potential as underutilized allies in the effort to end the HIV/AIDS epidemic. EDs especially could be useful in increasing the initiation of HIV pre-exposure prophylaxis (PrEP) – a key component of the National HIV/AIDS Strategy. EDs could be used as an access point where higher HIV-risk individuals, particularly those with STIs, can be initiated on PrEP and referred for further outpatient maintenance on PrEP. Dr. Solnick's K23 research project aims to improve ED-based HIV prevention in STI-diagnosed patients by developing and evaluating a protocol for Telephone Initiated PrEP Post-ED Discharge (TIPPED). The specific aims of her K23 research project are to (1) Develop a stakeholder-engaged TIPPED protocol and implementation strategy; (2) Adapt a tailored counseling message, a Persuasive Health Communication Intervention (PHCI), to encourage PrEP uptake during post-ED “callback” sessions as conducted by the ED clinician as part of their regular callback procedure to inform patients of the STI diagnoses; and (3) Implement and evaluate TIPPED, including a nested pilot randomized controlled trial of PHCI's impact on PrEP initiation and adherence. This research will incorporate both evaluations of implementation science-focused processes outcomes–feasibility, fidelity, acceptability–and clinical outcomes of PrEP initiation, linkage to care, and medication adherence. Advanced statistical methods, such as interrupted time-series methods, will be used to assess clinical outcomes. This career development plan will enable Dr. Solnick to build upon her experience as an emergency medicine physician and healthcare researcher to gain new expertise in (1) Implementation science approaches towards protocol development, deployment, and analysis; (2) Behavioral interventions in randomized controlled trial design; and (3) Advanced statistical methods in time-series data from electronic health records. She will receive in-depth mentorship from a multi-disciplinary research team of experts in the domains of implementation science, the HIV care continuum, clinical trial design, behavioral interventions, and statistical analysis. The results of this K23 will guide improvements to TIPPED and form the basis for Dr. Solnick’s subsequent R01 study. Her future R01 study will evaluate process and clinical outcomes relevant to implementing TIPPED in multiple EDs. The public health importance of this work is that it will contribute to expanded HIV prevention delivery and improved outcomes for individuals at risk of HIV infection, namely those with an STI receiving care in the ED.