This career development award will establish Dr. Anil Makam as a clinician-investigator focused on the impact of post-acute care on clinical and rehabilitation outcomes after acute illness in the elderly. This K23 award will provide him the support needed to develop expertise in 4 areas: (1) geriatric clinical training in post- acute care (2) health services research (HSR) using Medicare data; (3) advanced statistical methods in comparative effectiveness research (CER); and (4) geriatric rehabilitation outcomes. To achieve these goals, Dr. Makam has assembled an expert multidisciplinary team in HSR, CER, geriatrics, rehabilitation, and post- acute care. His primary mentor, Dr. Ethan Halm, has extensive experience in HSR, CER and mentoring junior faculty to become independent investigators. His secondary mentor, Dr. Ken Ottenbacher, is an expert in geriatric rehabilitation and post-acute care research. His scientific advisors include Dr. Jim Goodwin, a leading expert in using Medicare data for aging research, Dr. Ruben Amarasingham, an expert in the use of electronic heath record (EHR) data for CER, and Dr. Song Zhang, an expert in advanced biostatics. Dr. Makam will also benefit from the expertise of 2 renowned clinical advisors in geriatrics (Ruben) and post-acute care (Muldoon). The use of post-acute care among the elderly is rising, and accounts for 73% of the geographic variation in Medicare spending. Long-term acute care hospitals (LTACs) are the fastest growing segment of post-acute care. Despite this growth and variation, little is known about why hospitalized older adults are discharged to LTACs versus skilled nursing facilities (SNFs), the principal post-acute care alternate, and which setting will optimize their recovery. Informed by his clinical experience as a hospitalist and his preliminary data, Dr. Makam will conduct a series of national, regional, and local studies to answer these essential questions. He will use national Medicare data to identify patient, hospital, and regional-level factors associated with LTAC use (vs. SNFs) and describe outcomes related to LTAC and SNF care (Aim 1). To comparatively assess the effectiveness of LTACs vs. SNFs, Dr. Makam will use a linked regional EHR-Medicare dataset of 7 hospitals that includes clinically granular data on severity of illness (Aim 2). Lastly, he will conduct a pilot prospective cohort study to identify additional reasons for LTAC discharge not captured in either Medicare or EHR data (Aim 3a), and assess short-term cognitive and functional outcomes among LTAC and SNF survivors (Aim 3b). This research plan leverages existing institutional resources, including the CTSA and Dr. Halm's AHRQ-funded Center for Patient-Centered Outcomes Research, as well as Dr. Ottenbacher's and Dr. Goodwin's NIA-funded geriatric and rehabilitation outcomes research groups. Finally, this training and research will form the basis for two R01 applications to further study the comparative effectiveness of LTACs vs. SNFs and their associated long-term rehabilitation outcomes. This application and the subsequent R01s will directly inform practice and policy by building the evidence base to assist patients, providers, and payers to 'choose wisely' in post-acute care.