Racial and Ethnic Variations in Mortality Rates for Patients Undergoing Maintenance Dialysis Treated in US Territories Compared with the US 50 States

In the United States mortality rates for patients treated with dialysis differ by racial and/or ethnic (racial/ethnic) group. Mortality outcomes for patients undergoing maintenance dialysis in the United States territories may differ from patients in the United States 50 states. This retrospective cohort study of using US Renal Data System data included 1,547,438 adults with no prior transplantation and first dialysis treatment between April 1, 1995 and September 28, 2012. Cox proportional hazards regression was used to calculate hazard ratios (HRs) of death for the territories versus 50 states for each racial/ethnic group using the whole cohort and covariate-matched samples. Covariates included demographics, year of dialysis initiation, cause of kidney failure, comorbid conditions, dialysis modality, and many others. Of 22,828 patients treated in the territories (American Samoa, Guam, Puerto Rico, Virgin Islands), 321 were white, 666 were black, 20,299 were Hispanic, and 1542 were Asian. Of 1,524,610 patients in the 50 states, 838,736 were white, 444,066 were black, 182,994 were Hispanic, and 58,814 were Asian. The crude mortality rate (deaths per 100 patient-years) was lower for whites in the territories than the 50 states (14 and 29, respectively), similar for blacks (18 and 17, respectively), higher for Hispanics (27 and 16, respectively), and higher for Asians (22 and 15). In matched analyses, greater risks of death remained for Hispanics (HR, 1.65; 95% confidence interval, 1.60 to 1.70;