PROJECT SUMMARY/ABSTRACT Venous thromboembolism (VTE), a serious and life-threatening condition, has increased in incidence for hospitalized pediatric patients by 70-200%. This has led to increased morbidity, mortality and longer hospitalizations, and is thought to be due to more effective care of children with serious and life-threatening disorders. Unfortunately, it is unclear which children are at the highest risk of hospital acquired (HA) VTE and how to prevent these events due to many studies being single center with small case numbers. This study addresses the critical need to identify children at a high risk of HA-VTE using a risk assessment model (RAM), but a low risk of bleeding. This cohort will be used as the target population for trials evaluating the efficacy and safety of prophylactic anticoagulation in order to progress towards the long term goal of HA-VTE prevention in children. The overall objectives of this study are to (1) prospectively validate a pediatric HA-VTE RAM created through Dr. Jaffray’s multi-center Children’s Hospital Acquired Thrombosis (CHAT) Consortium using a case-control study design and electronic medical record review (EMR); (2) evaluate the incidence and characterization of bleeding in hospitalized children on and off anticoagulation through EMR review; and (3) explore barriers to provider engagement with RAM implementation by conducting focus groups and semi- structured interviews of inpatient medical teams using qualitative thematic analysis strategies. To achieve these research aims, Dr. Jaffray has the immediate career goals to obtain new knowledge, skills, and experience that will allow her to (1) analyze data from large datasets from multicenter studies and build and validate risk models through multivariate analysis; (2) develop qualitative research skills to design and analyze focus groups and semi-structured interviews; and (3) acquire the knowledge to plan and conduct randomized controlled trials. Achieving these career goals will support her long term career goal of becoming an independently funded, leader in the effort to determine efficacious and safe VTE prevention strategies in children through multicenter randomized controlled trials. Dr. Jaffray will accomplish her research and training aims with the support of her primary mentor, Dr. Guy Young (pediatric thrombosis clinical research), and co-mentors, Dr. Neil Goldenberg (pediatric clinical trial research), Dr. Ernest Amankwah (biostatics), Dr. Neil Zakai (adult thrombosis clinical research) and Dr. Elizabeth Burner (qualitative research). Dr. Jaffray’s plan for career development is enhanced by the outstanding research environment at Children’s Hospital Los Angeles and The University of Southern California, which provides junior faculty members with numerous didactic and training opportunities designed specifically to facilitate the transition to research career independence. By completing her research and training aims, Dr. Jaffray will ta...