Race differences in prevalence of chronic kidney disease among young adults using creatinine-based glomerular filtration rate-estimating equations

Department of Medicine, University of California San Francisco, San Francisco, CA, USA.
Nephrology Dialysis Transplantation (Impact Factor: 3.58). 12/2010; 25(12):3934-9. DOI: 10.1093/ndt/gfq299
Source: PubMed


Despite a higher incidence of end-stage renal disease (stage 5), blacks have been shown to have the same or lower prevalence of chronic kidney disease (CKD stages 3 and 4). Current creatinine-based glomerular filtration rate (GFR)-estimating equations may misclassify young, healthy blacks.
Among 3501 young adults (mean age 45), we compared the prevalence of CKD in blacks and whites using the Modification of Diet in Renal Disease (MDRD) and the CKD Epidemiology Collaboration (CKD-EPI) equations. In addition, we used measured creatinine excretion rates to determine the actual excretion ratio for CARDIA (race coefficient 12%) and applied this to the CKD-EPI equation. We also studied the prevalence of CKD risk factors among black and white participants near the CKD threshold cut-off (eGFR CKD-EPI 60-80 mL/min/1.73 m(2)) to estimate the relative likelihood of misclassification in blacks and whites.
Using the MDRD equation, prevalence of CKD stages 4 and 5 was higher for blacks compared with whites (0.6% vs. 0.1%, P-value 0.05). In contrast, prevalence of eGFR <60 mL/min/1.73 m(2) was significantly higher for whites (3.6%) compared with blacks (1.9%), due to higher prevalence of stage 3 among whites. Prevalence of CKD was similar for blacks and whites using CKD-EPI equation (1.2%), but was higher among blacks when using the CARDIA-derived race coefficient (1.6% vs.1.2%, P-value = 0.03). Among persons with eGFR by CKD-EPI of 60-80 mL/min/1.73 m(2), blacks had higher levels of albuminuria, uric acid, systolic blood pressure and higher diabetes prevalence.
CKD classification among young blacks is very sensitive to the race coefficients. Despite whites having higher rates of CKD stage 3, blacks with eGFRs just above the CKD threshold had higher rates of CKD risk factors. Current equations used to define CKD may systematically miss a high-risk group of blacks at a time in the disease course when interventions are crucial.

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Available from: Kirsten Bibbins-Domingo, Dec 31, 2013
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    • "Finally, the MDRD and CKD-EPI equations were developed in patients with chronic kidney disease stage 4–5. The study of Peralta et al. [24] strongly suggests that even in a cohort of African-American, the race correction factors of 1.21 for the MDRD-v4 et 1.16 for the CKD-EPI equations are probably too high for young patients with CKD-EPI estimated GFR comprised between 60 and 80 mL/min/1.73 m2 and should rather be 1.12. "
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    ABSTRACT: Regarding the high prevalence of African American patients with ESRD, it is important to estimate the prevalence of early stages of chronic kidney disease in this specific population. Because serum creatinine concentration is dependent on muscular mass, an ethnic factor has to be applied to creatinine-based equations. Such ethnic factors have been proposed in the Modification of Diet in Renal Disease (MDRD) study equation and in the more recent Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations. This review analyzes how these correction factors have been developed and how they have, or have not, been validated in external populations. It will be demonstrated that the African American factor in the MDRD study equation is accurate in African American chronic kidney disease (CKD) patients. However, it will be shown that this factor is probably too high for subjects with a GFR of ≥60 ml/min per 1.73 m(2), leading to an underestimation of the prevalence of CKD in the global African American population. It will also be confirmed that this ethnic factor is not accurate in African (non-American) subjects. Lastly, the lack of true external validation of the new CKD-EPI equations will be discussed. Additional trials seem necessary in American African and African populations to better estimate GFR and apprehend the true prevalence of CKD in this population with a high renal risk.
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