UC Irvine

Background

Observational studies indicate greater survival in African American and Hispanic maintenance hemodialysis patients compared with their non-Hispanic white counterparts, although African Americans have shorter life expectancy than whites in the general population. We hypothesized that this apparent survival advantage is due to a more favorable nutritional/inflammatory profile in minority hemodialysis patients.

Study design

We examined the association between race/ethnicity and 5-year survival before and after adjustment for case-mix and surrogates of the malnutrition-inflammation complex syndrome (MICS) using Cox regression with or without matched sampling in a large cohort of adult hemodialysis patients.

Setting & participants

124,029 adult hemodialysis patients, including 16% Hispanics, 49% non-Hispanic whites, and 35% African Americans.

Predictors

Race/ethnicity before and after adjustment for MICS, including values for body mass index, serum albumin, total iron-binding capacity, ferritin, creatinine, phosphorus, calcium, bicarbonate, white blood cell count, lymphocyte percentage, hemoglobin, and protein intake.

Outcomes

5-year (July 2001 to June 2006) survival.

Results

In dialysis patients, blacks and Hispanics had lower mortality overall than non-Hispanic whites after traditional case-mix adjustment. However, after additional control for MICS, Hispanics had mortality similar to non-Hispanic whites, and African Americans had even higher mortality. Unadjusted, case-mix-, and MICS-adjusted HRs for African Americans versus whites were 0.68 (95% CI, 0.66-0.69), 0.89 (95% CI, 0.86-0.91), and 1.06 (95% CI, 1.03-1.09) in the unmatched cohort and, 0.95 (95% CI, 0.90-0.99), 0.89 (95% CI, 0.84-0.94), and 1.16 (95% CI, 1.07-1.26) in the matched cohort, and for Hispanics versus whites, 0.66 (95% CI, 0.64-0.69), 0.84 (95% CI, 0.81-0.87), and 0.97 (95% CI, 0.94-1.00) in the unmatched cohort and 0.89 (95% CI, 0.84-0.95), 0.88 (95% CI, 0.83-0.95), and 0.98 (95% CI, 0.91-1.06) in the matched cohort, respectively.

Limitations

Adjustment cannot be made for unmeasured confounders.

Conclusions

Survival advantages of African American and Hispanic hemodialysis patients may be related to differences in nutritional and inflammatory status. Further studies are required to explore these differences.