PROJECT SUMMARY The end stage renal disease (ESRD) population on dialysis is a longstanding challenge to manage. This stems from high health care needs, and comorbidities, with mortality rates 10-fold greater than age- matched controls and costs totaling 7% of Medicare’s budget. In contrast to peer countries, nearly 90% of dialysis in the United States is performed in-center, at a dialysis facility. The reasons for this are often not clinical, but related to financial investments in dialysis facilities, and the lower level of comfort by nephrologists for home dialysis modalities. Many believe that increased use of home dialysis will substantially improve care of the chronic dialysis population, given theoretical physiological advantages (gentler and more continuous), and associations with better survival and lower health care costs. However, the evidence comparing home versus in-center dialysis remains highly controversial given the paucity of controlled clinical trials. Most observational comparisons are plagued by potential issues of selection. Nevertheless, the Center for Medicare & Medicaid Innovation moved forward with the ESRD Treatment Choices (ETC) Model in January 2021, providing robust financial incentives for dialysis centers and nephrologists in randomly selected hospital referral regions to shift dialysis care delivery from the facility to the patient home or to transplantation. Given severe constraints on organ availability for transplantation, this is expected to lead to rapid increases in use of home dialysis. With mandatory and random selection of model participants, there is an unprecedented opportunity to develop less biased assessments of the relative merits of home versus in-center dialysis. First, preservation of residual kidney function and continuous dialysis with home modalities has been proposed to better control uremia and volume overload, conferring a survival benefit and reduced overall healthcare utilization. Second, there are potential trade-offs with use of in-center versus home dialysis that can affect the care of comorbidities that commonly afflict dialysis patients. For example, home modalities may better control heart failure, yet more frequent medical contacts with providers with in-center dialysis may allow early attention to developing issues that can avert acute exacerbations. Third, populations at high social risk (e.g., patients of Black race, dual Medicare-Medicaid eligibles) have lower access to home dialysis, often justified on the basis of poor housing quality and unstable living conditions. It is therefore particularly important to understand whether such patients will realize a net benefit from home dialysis. Leveraging the ETC model’s quasi- experimental design we propose a study with these Aims: 1) To compare overall survival and healthcare spending between ESRD patients on home versus in-center dialysis; 2) To compare outcomes of care for specific comorbidities between ESRD patients on home versu...