“Although we have a vast number of tools to prevent kidney failure or slow down progression of kidney disease, Black individuals with HIV still have one of the highest incidences of kidney failure in the United States,” Anthony Muiru, MD, explains. “It is therefore imperative that we detect kidney disease early to employ preventative tools.”
Previously, estimated glomerular filtration rate (eGFR) equations used a race coefficient to account for the race of the individual undergoing testing. “The race coefficient in eGFR assigned a higher eGFR for all Black individuals, and we wondered whether this hampered clinicians’ ability to detect kidney disease early,” Dr. Muiru says.
In 2022, a new, race-free eGFR calculation was introduced, with endorsement from the National Kidney Foundation and the American Society of Nephrology’s Task Force. Dr. Muiru and colleagues wrote that it was unclear whether the association of race with chronic kidney disease (CKD) progression was reliant on the use of the race coefficient and whether the race-free equation would decrease bias “in the estimated association of race with CKD progression” among people with HIV.
For a study published in Clinical Infectious Diseases, Dr. Muiru and colleagues defined eGFR stages with the original, race-adjusted CKD Epidemiology Collaboration (CKD-EPI) eGFR creatinine equation and the new race-free CKD-EPI eGFR creatinine equation. They estimated the 5-year likelihood of transitioning from baseline kidney function to later eGFR stages and assessed the association of race (Black vs White) with rates of CKD progression.
Race Coefficient May Have ‘Biased’ Prior Studies
The study included 69,125 individuals with HIV and CKD (45% Black; 40% White). Baseline CD4 counts and HIV viral loads were similar between these two groups, according to the study results.
“Using the new race-free equation, we reclassified a significant group of Black participants with HIV as having worse CKD at baseline,” Dr. Muiru says. In total, 16% of Black participants were reclassified into a more severe eGFR stage at baseline, according to the study results.
“This is key, because when eGFR drops to a certain threshold, clinicians can initiate evidence-based preventative interventions.”
According to Dr. Muiru, the researchers also found that, when using the race-free eGFR creatinine equation to assess kidney function, Black participants had a greater risk for disease progression across all baseline eGFR stages.
compared with White participants. “This indicates that previous studies that suggested Black individuals have accelerated rates of kidney disease progression only in later stages of CKD may have been biased by the race coefficient in eGFR,” he says (Table).
As a result, the practice of “automatically designating higher kidney function based solely on race may have systemically impeded our ability to identify a subgroup of Black individuals living with HIV who are at higher risk for CKD progression,” Dr. Muiru notes, which “may have interfered with our ability to slow progression.”
Implement Race-Free eGFR Equation ‘Immediately’
The study results demonstrate that “adoption of the race-free 2021 CKD-EPI eGFR creatinine equation must be applied immediately,” he continues. “In addition, we must pay attention to the rate of eGFR decline, not just a single number.”
The study team acknowledged that “additional factors beyond the race coefficient, such as socioeconomic status, may complicate clinical care and kidney disease progression,” and suggested that future studies include “rigorous” measures of social determinants of disease.
Further, clinicians still need better strategies for estimating kidney function, Dr. Muiru notes. “We also need newer biomarkers to detect kidney disease early,” he says. “Lastly, we need to identify and eliminate barriers to care delivery. More importantly, we must address the unacceptable racial disparities in rates of kidney failure.”