eGFR race adjustment disfavors Black adults, impacts CKD diagnoses
The prevalence of chronic kidney disease among Black adults doubled when race adjustment was excluded from eGFR equations, according to a study.
This finding can implicate drug-dosing decisions and improve the accuracy of kidney failure prediction among higher-risk Black adults, according to Vishal Duggal, MD, a post-doctoral fellow in medical informatics at the Veterans Affairs Palo Alto Heath Care System, and colleagues.
“Estimation of GFR without race adjustment reclassifies a sizeable fraction of Black adults with CKD. Because the race adjustment factor is constant and CKD prevalence is higher at earlier stages, its elimination leads to a larger effect on CKD prevalence at earlier vs. more advanced stages,” they wrote.
The researchers set out to uncover the implications on the prevalence of CKD and management strategies with the removal of race adjustment. This population-based study included cross-sectional and longitudinal data from adults in the National Health and Nutrition Examination Survey (NHANES) from 2015 to 2016 and the Veterans Affairs Health Care System in 2015. Duggal and colleagues assessed the dosages of common medications impacted by kidney function and compared prognostic accuracy of the Kidney Failure Risk Equation with and without race adjustment of eGFR in the VA group. They compared this with the prevalence of CKD in the NHANES as a population sample.
The study included participants with recorded outpatient serum creatinine measurements. Participants were characterized into Black or “non-Black” racial cohorts, according to the study. Researchers also recorded age, sex, height and weight of each participant in addition to diabetes status when provided.
Within the NHANES cohort, a weighted 10.9% of the U.S. population self-reported as Black, while the VA cohort included 784,337 Black veterans (17.5%).
The mean eGFR in the NHANES cohort was 96.3 mL/min per 1.73 m² with the original CKD-EPI equation and was 94.7 mL/min per 1.73 m² without race adjustment. Among Black participants in the NHANES cohort, the eGFR was 104.5 mL/min per 1.73 m² with the original CKD-EPI equation and was 90.2 mL/min per 1.73 m² without race adjustment.
The mean eGFR in the VA cohort was 80 mL/min per 1.73 m² with the original CKD-EPI equation and was 78 mL/min per 1.73 m² without race adjustment. Among Black veterans, the eGFR was 87.3 with the original CKD-EPI equation and was 75.7 without race adjustment.
Impact on CKD diagnoses
The overall estimated prevalence of CKD in the NHANES group increased from 5.9% to 6.5% of the population after the race adjustment was removed. Among Black adults, prevalence of CKD increased from 5.2% to 10.6%. Also, 5.6% of Black adults were reclassified to CKD stage 3 and 6.3% of participants who were at stage 3 were reclassified to CKD stage 4 after eliminating the race adjustment.
The prevalence of CKD overall increased from 17.9% to 19.6% among Black veterans and the estimated prevalence of CKD among Black adults increased from 12.4% to 21.6%. In the VA cohort, 71,805 veterans were reclassified to CKD stage 3 and 5,444 who were previously at CKD stage 3 were reclassified to CKD stage 4 with the removal of the race adjustment. Moreover, 29.1% of the Black veterans previously at CKD stage 4 were reclassified to CKD stage 5. CKD prevalence altered the most among older adults and those with diabetes.
“We found that removal of the adjustment for Black race from the CKD-EPI creatinine equation would double the prevalence of CKD in Black adults, resulting in a 0.6% absolute increase in the prevalence of CKD nationally and a 1.7% absolute increase in the prevalence of CKD in the VA population,” Duggal and colleagues wrote. “The potential effect of
changes in eGFR on medication dosing could affect a substantial number of Black adults, for example, up to 41% of gabapentin users and more than 25% of metformin and ciprofloxacin users. The discrimination of kidney failure risk prediction using GFR without race adjustment remained high, and calibration among Black adults was improved at higher levels of predicted risk.”