Younger black patients have a higher risk of infection mortality that is mostly non-dialysis related: A national study of cause-specific mortality among U.S. maintenance dialysis patients.

INTRODUCTION

While it has been well documented that in the U.S., black and Hispanic dialysis patients have overall lower risks of death than white dialysis patients, little is known whether their lower risks are observed in cause-specific deaths. Additionally, recent research reported that younger black patients have a higher risk of death, but the source is unclear. Therefore, this study examined cause-specific deaths among US dialysis patients by race/ethnicity and age.

METHODS

This national study included 1,255,640 incident dialysis patients between 1995 and 2010 in the United States Renal Data System. Five cause-specific mortality rates, including cardiovascular (CVD), infection, malignancy, other known causes (miscellaneous), and unknown, were compared across blacks, Hispanics, and whites overall and stratified by age groups.

FINDINGS

After multiple adjustments, Hispanic patients had the lowest risk of mortality for every major cause in almost all ages. Compared with whites, blacks had a lower risk of death from CVD, malignancy and miscellaneous causes in most age groups, but not from infection. In fact, blacks had a higher risk of infection death than whites in ages 18-30 years (HR [95% CI] 1.94 [1.69-2.23]; P < 0.001), 31-40 years (HR 1.51 [1.40-1.63]; P < 0.001) and 41-50 years (HR 1.07 [1.02-1.12]; P = 0.009), which were partially attributed to their higher prevalence of AIDS nephropathy. For each race/ethnicity, more than two-thirds of infection deaths were due to non-dialysis related infections.

DISCUSSION

Hispanics had the lowest risk for each major cause of death. Blacks were less likely to die than whites from most causes, except infection. The previously reported higher overall mortality rate for younger blacks is attributed to their two-fold higher infection mortality, which is mostly non-dialysis related, suggesting a new direction to improve their overall health status. Research is greatly needed to determine social and biological factors that account for the survival gap in dialysis among different racial/ethnic groups.