Please join us for a UW Data Science Seminar featuring recent UW Rehabilitation Science PhD graduate Rachael Rosen on Tuesday, October 7th from 4:30 to 5:20 p.m. PT. The seminar will be held in IEB G109.
“Modeling Patient Outcomes After Amputation: Comparing Machine Learning and Traditional Approaches”
Abstract: Major lower limb amputation (LLA) in older adults often leads to poor outcomes, including hospital readmission and death within months of discharge. This research used national Medicare data (2018–2021) to model two outcomes after LLA: 180-day hospital readmission and post-discharge mortality. Each was evaluated using both traditional statistical models and machine learning (ML) methods to compare predictive performance and clinical utility. For readmission, a competing risks model was compared to a random survival forest. ML improved predictive accuracy and captured non-linear patterns not accounted for by traditional methods. High-risk subgroups were characterized by intensive care unit stays, high comorbidity burden, prolonged hospitalization, and end-stage renal disease. For mortality, both a Cox model and a survival random forest performed similarly in terms of prediction. However, violation of the proportional hazards assumption made the ML model more appropriate. Mortality risk was highest for individuals discharged to hospice, nursing facilities, or home without services, and lower for those discharged with rehabilitation or home health care. ML methods offered greater flexibility and identified risk patterns missed by traditional approaches. These results demonstrate how ML can enhance outcome prediction in clinical populations and highlight opportunities to support discharge planning for patients undergoing major amputation.
Biography: Rachael Rosen, PhD, is a rehabilitation researcher with expertise in health services research, prosthetics and orthotics, and machine learning applications in clinical outcome modeling. She recently completed her PhD in Rehabilitation Science at the University of Washington, where her dissertation examined access to post-acute care, hospital readmission, and mortality following major lower limb amputation. Her work used national Medicare claims data to identify disparities and evaluate predictive models across sociodemographic and clinical subgroups.Before transitioning to research, Dr. Rosen practiced clinically as a certified prosthetist- orthotist (CPO) in Level I trauma centers and pediatric hospitals in Washington and Mississippi. These experiences shaped her interest in policy-driven research after observing how administrative and insurance-related barriers limited rehabilitation access for patients with complex care needs. Since 2018, she has served as a research scientist in the Department of Rehabilitation Medicine at UW, contributing to the development of outcome measures and leading projects focused on mobility, equity, and post-acute care delivery.
The 2025-2026 seminars will be held in person, and are free and open to the public.