Association of race and body mass index with ESRD and mortality in CKD stages 3-4: results from the Kidney Early Evaluation Program (KEEP)

Abstract

Background: A recent cross-sectional analysis of Kidney Early Evaluation Program (KEEP) participants suggested that obesity is a heterogeneous disease state in African Americans and whites with chronic kidney disease (CKD).

Study design: In longitudinal analyses spanning 8 years of follow-up, we examined whether race and body mass index (BMI) influence end-stage renal disease (ESRD) and mortality rates in participants with CKD stages 3-4.

Setting & participants: KEEP participants were included in this analysis if they met the following criteria: (1) estimated glomerular filtration rate (eGFR) of 15-59 mL/min/1.73 m(2), (2) white or African American race, and (3) no previous dialysis or transplantation.

Outcomes & measurements: Survival analyses were performed for the outcomes of ESRD, death, and combined outcome of ESRD or death.

Results: Of 14,631 participants with CKD stages 3-4, 28% were African American and 72% were white. African American participants had higher rates of obesity and hypertension, with a higher baseline mean eGFR, higher prevalence of albuminuria, and greater degree of anemia compared with whites. In multivariable models, African American race increased the risk of ESRD (HR, 1.66; 95% CI, 1.26-2.07), but not death (HR, 0.89; 95% CI, 0.76-1.03). In these models, male sex, hypertension, diabetes, lower baseline eGFR, and albuminuria were predictive of higher rates of ESRD; age, male sex, diabetes, lower baseline eGFR, and albuminuria were predictive of overall mortality. There was no significant interaction between race and BMI in the adjusted model for outcomes of ESRD (P = 0.7) or death (P = 0.3).

Limitations: Baseline values used in the analysis are from a cross-sectional data set. Dyslipidemia and secondary hyperparathyroidism were not accounted for in the analysis.

Conclusions: African American race was associated with a higher incidence of ESRD, but not mortality. Although obesity may be a heterogeneous disease state in African Americans and whites with CKD, there does not appear to be a significant interaction between race and BMI in progression to ESRD or death.