Among equations for estimating glomerular filtration rate (eGFR) developed by the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI), the 2021 race-free eGFR equation including both creatinine and cystatin C (eGFRcr-cys) is preferable to the 2021 creatinine-only equation refit without the race coefficient (eGFRcr) for documenting racial disparities in the risk for kidney failure and death, investigators reported in JAMA.
The 2021 race-free eGFRcr-cys appropriately shows the racial gaps that were previously observed with the conventional 2009 creatinine-based equation including the race coefficient. The 2021 race-free eGFRcr inappropriately diminishes these racial gaps. Other equations also appeared suboptimal.
Josef Coresh, MD, PhD, of Johns Hopkins Bloomberg School of Public Health and the Chronic Kidney Disease Prognosis Consortium Data Coordinating Center, Baltimore, Maryland, and colleagues analyzed 62,011 adults from 5 general population and 3 chronic kidney disease (CKD) cohorts from 1988 to 2018. Of these, 20,773 individuals were Black and 41,238 were non-Black race.
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Both 2021 equations documented a greater burden of CKD in the Black population. The prevalence ratio of CKD (eGFR less than 60 mL/min/1.73 m2) among Black vs non-Black patients was 1.2 using eGFRcr-cys and 1.8 using race-free eGFRcr.
During a mean 13 years, kidney failure requiring renal replacement therapy (KFRT) occurred in 8% vs 4% of Black and non-Black patients, respectively; death occurred in 34% vs 39%, respectively. At an eGFR of 60 mL/min/1.73 m2, the 5-year absolute risk difference of KFRT among Black vs non-Black patients was 1.3% using race-free eGFRcr-cys compared with 0.37% using race-free eGFRcr.
At an eGFR of 60 mL/min/1.73 m2, the hazard ratios for all-cause and cardiovascular mortality using the eGFRcr-cys were 1.1 and 1.3, respectively — significantly higher for Black than non-Black individuals. Mortality risks did not differ significantly between race groups using the 2021 eGFRcr.
“These findings offer compelling evidence that the new 2021 eGFRcr-cys [based on age and sex] consistently estimates greater prevalence of decreased kidney function for Black individuals compared with non-Black individuals,” L. Ebony Boulware, MD, MPH, and colleagues from Duke University School of Medicine in Durham, North Carolina, commented in an accompanying editorial. “The equation also appropriately quantifies racial disparities in kidney disease risk and mortality across the spectrum of kidney dysfunction, a crucial prerequisite for efforts to intervene on and track improvements in kidney health equity.”
References
Gutiérrez OM, Sang Y, Grams ME, et al. Association of estimated GFR calculated using race-free equations with kidney failure and mortality by Black vs Non-Black race. JAMA. Published online June 6, 2022. doi:10.1001/jama.2022.8801
