Race, Age, and Mortality Among Patients Undergoing Dialysis

Abstract

To the Editor: Ms Kucirka and colleagues found that black dialysis patients younger than 50 years had higher mortality than white dialysis patients of the same age group, whereas older black patients had lower mortality. However, the authors made no distinction between Hispanic and non-Hispanic white patients, and apparently both ethnic groups were collapsed into a single reference group for the sake of comparison with black patients. Hispanic patients make up close to one-fifth of the US dialysis population. The dialysis incidence rate in the Hispanic population is 1.5 times greater than among the non-Hispanic white population. Nonetheless, Hispanic dialysis patients have had better survival over the past several decades compared with non-Hispanic white patients, with a death rate of 180 per 1000 patient-years at risk compared with 207 per 1000 patient-years at risk for non-Hispanic white patients. The causes of these ethnic disparities remain largely unknown. In a recent study, we confirmed that both black and Hispanic dialysis patients had better survival than nonHispanic white dialysis patients. The survival advantage seen in black patients was accounted for by their better nutritional status, whereas Hispanic patients maintained their lower risk of death even after adjustment for surrogates of nutrition and inflammation. The reported findings of higher mortality in young black patients by Kucirka et al may be flawed because the reference group of combined Hispanic and nonHispanic white patients was too heterogeneous to serve as an appropriate reference group. Discovering the factors responsible for the survival advantage of black and Hispanic patients may have clinical and public health implications by leading to methods for improving outcomes in dialysis patients.