UCSF

Background

Dietary acid load (DAL) contributes to the risk of CKD and CKD progression. We sought to determine the relation of DAL to racial/ethnic differences in the risk of end-stage renal disease (ESRD) among persons with CKD.

Methods

Among 1,123 non-Hispanic black (NHB) and non-Hispanic white (NHW) National Health and Nutrition Examination Survey III participants with estimated glomerular filtration rate 15-59 mL/min/1.73 m2, DAL was estimated using the Remer and Manz net acid excretion (NAEes) formula and 24-h dietary recall. ESRD events were ascertained via linkage with Medicare. A competing risk model (accounting for death) was used to estimate the hazard ratio (HR) for treated ESRD, comparing NHBs with NHWs, adjusting for demographic, clinical and nutritional factors (body surface area, total caloric intake, serum bicarbonate, protein intake), and NAEes. Additionally, whether the relation of NAEes with ESRD risk varied by race/ethnicity was tested.

Results

At baseline, NHBs had greater NAEes (50.9 vs. 44.2 mEq/day) than NHWs. It was found that 22% developed ESRD over a median of 7.5 years. The unadjusted HR comparing NHBs to NHWs was 3.35 (95% CI 2.51-4.48) and adjusted HR (for factors above) was 1.68 (95% CI 1.18-2.38). A stronger association of NAE with risk of ESRD was observed among NHBs (adjusted HR per mEq/day increase in NAE 1.21, 95% CI 1.12-1.31) than that among NHWs (HR 1.08, 95% CI 0.96-1.20), p interaction for race/ethnicity × NAEes = 0.004.

Conclusions

Among US adults with CKD, the association of DAL with progression to ESRD is stronger among NHBs than NHWs. DAL is worthy of further investigation for its contribution to kidney outcomes across race/ethnic groups.