For a study, researchers sought to determine if eGFR equations with and without race and cystatin C showed racial variations in the risk of kidney failure with replacement therapy (KFRT) and death in communities with Black and non-Black individuals.

Individual-level data analysis of 62,011 people from 5 general population and 3 chronic kidney disease (CKD) cohorts in the United States with serum creatinine, cystatin C, and KFRT and mortality follow-up from 1988 to 2018. The prevalence of reduced eGFR at baseline and the hazard ratios for KFRT and mortality in Black versus non-Black patients were estimated after controlling for age and gender. Analyses were carried out within each cohort and model random-effect meta-analyses. 

Among 62,011 participants (20,773 Black and 41,238 non-Black; mean age, 63 years; 53% women), the prevalence ratio (95% CI; percent prevalences) of eGFR less than 60 mL/min/1.73 m2 comparing Black with non-Black participants was 0.98 (95% CI, 0.93-1.03; 11% vs 12%) for eGFRcr with race, 0.95 (95% CI, 0.91-0.98; 17% vs 18%) for eGFRcys, and 1.2 (95% CI, 1.2-1.3; 13% vs 11%) for eGFRcr-cys but was 1.8 (95% CI, 1.7-1.8; 15% vs 9%) for eGFRcr without race. During a 13-year average follow-up, 8% and 4% of Black and non-Black individuals, respectively, had KFRT, and 34% and 39% died. For all equations, lower eGFR was linked with a substantially higher probability of both outcomes. At an eGFR of 60 mL/min/1.73 m2, the hazard ratios for KFRT compared to non-Black individuals were 2.8 (95% CI, 1.6-4.9) for eGFRcr with race, 3.0 (95% CI, 1.5-5.8) for eGFRcys, and 2.8 (95% CI, 1.4-5.4) for eGFRcr-cys versus 1.3 ( The 5-year absolute risk differences for KFRT comparing Black and non-Black participants were 1.4% (95% CI, 0.2% -2.6%) for eGFRcr with race, 1.1% (95% CI, 0.2% -1.9%) for eGFRcys, and 1.3% (95% CI, 0%-2.6%) for eGFRcr-cys vs 0.37% (95% CI, For mortality, similar trends were seen.

The eGFR equation without race that included creatinine and cystatin C, but not the eGFR equation without race that included creatinine without cystatin C, demonstrated racial differences in the risk of KFRT and mortality across the eGFR range in the retrospective analysis of 8 US cohorts including Black and non-Black individuals. For analyzing racial variations in the risk of KFRT and mortality linked with low eGFR, the eGFRcr-cys equation may be superior to the eGFRcr equation without race.