Race-dependent survival disparity on hemodialysis: Higher serum aluminum as an independent risk factor for higher mortality in whites

Abstract

The mortality rate on hemodialysis therapy remains unacceptably high, and it is worse in whites than blacks. Substantially elevated serum aluminum levels have been shown to predict mortality on hemodialysis. However, whether this is a factor in the race-dependent survival difference on hemodialysis therapy is presently unknown. To determine the relevance of serum aluminum level on race-dependent survival disparity on chronic hemodialysis therapy, 1-year survival of 118 whites was prospectively compared with 473 age- and sex-matched blacks. The variables predictive for survival, including serum aluminum level, were defined separately in whites and blacks using Cox univariate and multivariate analyses. The 1-year mortality rate was significantly greater in whites than blacks (18% versus 12%; P < 0.001). Serum albumin level, body mass index (BMI), and creatinine level had a positive influence, whereas age had a negative influence on survival in both groups in the univariate analysis. The mean serum aluminum level was significantly greater in whites (n = 118) than blacks (n = 473; 20 ± 2.3 versus 14 ± 0.6 [SE] ng/mL; P = 0.0009) and was not caused by increased duration on dialysis, increased prescription of aluminum-containing phosphate binders, or reduced delivered dose of dialysis. Unlike the blacks, serum aluminum levels had a significant negative influence on the survival of whites, and this persisted in multivariate analysis after controlling for age, sex, diabetes, albumin level, creatinine level, and BMI (relative risk, 1.013; 95% confidence interval, 1.004 to 1.023; P < 0.007). In summary, this study suggests that whites undergoing hemodialysis may have greater serum aluminum levels than blacks, which might contribute to the whites’ greater rate of mortality. Because hyperaluminemia is a modifiable risk factor, studies are required to verify our findings, explore the mechanism of elevated aluminum levels in whites, and test the hypothesis that reducing serum aluminum levels in whites may improve their survival.