PROJECT SUMMARY Hurricane Maria was one of the worst natural disasters in modern US history. Maria caused an estimated 3,000 deaths and $139 billion in damage to the Island's infrastructure. Hurricane Maria caused prolonged electricity outages that prevented people with kidney failure from accessing care. Most patients with kidney failure receive hemodialysis at outpatient dialysis facilities three times a week. Access to dialysis during Maria was limited or non-existent in some areas in Puerto Rico, and some patients needed to travel to other facilities on the island or to the US mainland to receive care. Maria may have disrupted regular dialysis care, leading to increased risk of death, hospitalization, or other adverse events. There is a crucial need to understand the consequences of this large-scare natural disaster among this vulnerable population, given social and healthcare inequalities, and the extensive level of destruction caused by Maria on the island. Using longitudinal data for all dialysis patients in Puerto Rico from the US Renal Data System and qualitative interviews with providers and clinic staff, our specific aims are as follows: 1) Examine long-term trends in outmigration among persons with kidney failure in Puerto Rico, pre- and post-Hurricane Maria. Our working hypothesis is that Hurricane Maria increased out-migration of kidney failure patients relative to the pre-disaster period; 2) Estimate the long-term impact of Hurricane Maria on mortality and hospitalizations among migrant and non- migrant patients with kidney failure, pre- and post-Maria. Our working hypothesis is that following Maria, persons who migrated outside of Puerto Rico will experience increased mortality and hospital admissions compared to persons who did not migrate out of Puerto Rico; and 3) Examine dialysis providers' strategies and perceived barriers to mitigating the Hurricane's effects on patients with kidney failure and understand the long- term consequences for dialysis provider organizations and staff through qualitative interviews. We expect these interviews will provide in-depth, novel insights into providers' strategies to maintain continuity of care and avoid dialysis facility closures. This proposal is a direct response to the FOA (PA-20-172) “Long-Term Effects of Disasters on Health Care Systems Serving Health Disparity Populations.” This proposal is a first step towards a broader understanding of the impact of Hurricane Maria on complex populations. The proposed project aligns with the NIMHD areas of interest, including U.S. territories, socioeconomically disadvantaged populations, as well as the overarching goal of understanding the long-term effects of natural disasters on health disparity populations and the health care systems that serve them. We use longitudinal data for patients undergoing dialysis (~14,000 patients since 2010) with rich clinical and socioeconomic covariates that allow us to track migration patterns and mortality and h...