Cystatin C-based eGFR changes Black patients’ CKD prevalence less than race-free equations
Cystatin C-based eGFR had the smallest impact on eGFR values for Black patients with chronic kidney disease compared with race-free alternatives for measuring eGFR values, according to a published study.
“Medical centers nationwide are considering race-free equations to improve the reporting of eGFR,” James A. Diao, MD, of the computational health informatic program at Boston Children’s Hospital and the department of biomedical informatics at Harvard Medical School, and colleagues wrote. “Numerous alternatives have been proposed and implemented — including removal of the coefficient for Black race — with substantial implications for guideline-recommended care.”
Diao and colleagues analyzed the data of 4,434 adults collected through the National Health and Nutrition Examination Survey between 1999 and 2002 and calculated cystatin C-based eGFR (eGFRcys) and creatinine-based eGFR (eGFRcr) with and without race as a factor.
With eGFRcys, CKD prevalence changed the least (0.7%) and had the smallest average change in eGFR (–0.8; 95% CI, –2.6 to 0.2 mL/min per 1.73 m2) among Black participants compared with race-free and race-blended equations. The smallest difference in CKD prevalence between Black patients and patients categorized as “white/other” occurred with eGFRcys (3.7%) compared with other race-free equations (6.1% to 7.4%).
Cystatin C- and creatinine-based eGFR (eGFRcr-cys) had the highest eGFR values when compared with common eGFR equations.
Decreasing the race coefficient for CKD Epidemiology Consortium eGFR from 100% to 0% “if Black” increased CKD prevalence in Black participants from 17.7% to 20.4% and the proportion of Black adults with eGFR less than 60 mL/min per 1.73 m2 (5.7% to 9.4%), less than 45 mL/min per 1.73 m2 (2.5% to 3.8%) and less than 30 mL/min per 1.73 m2 (1.3% to 1.6%). It also created a larger average change from eGFRcr-cys for Black participants (–18.8; 95% CI, –20.3 to –17.5 mL/min per 1.73 m2) than participants of other races when assigned as 100% “if Black” (10; 95% CI, 8.8 to 11.4). With the Modification of Diet in Renal Study eGFRcr, a similar effect occurred.
The study was limited by potential nonrepresentation of earlier cohorts and absence of measured GFR data, according to researchers.
Diao and colleagues emphasized the significance of systemic racism and population shifts in eGFR when examining diagnosis, management and outcomes of CKD among Black individuals, suggesting future studies should further examine race-free equations.
“Beyond social determinants of kidney disease, improved race-free equations may also consider genetic factors (eg, APOL1), although their clinical utility is unclear,” they wrote. “In the meantime, further studies should investigate and compare accuracies of currently available race-free equations using mGFR collected from diverse populations.”