Race may have little influence on accurate measurement of GFR
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Race may have little influence in determining an accurate eGFR when assessing patients for kidney disease, according to study results published in American Journal of Kidney Diseases.
“Assessment of glomerular filtration rate (GFR) is critical for many aspects of medical practice,” Lesley A. Inker, MD, MS, of the division of nephrology at Tufts Medical Center in Boston, and colleagues wrote. “GFR estimation based on creatinine and cystatin C together (eGFRcr-cys) is more accurate than eGFR based on either creatinine or cystatin C alone, but the inclusion of creatinine in eGFRcr-cys requires specification of a person’s race. Beta-2-microglobulin (B2M) and beta-trace protein (BTP) are alternative filtration markers that appear to be less influenced by race than creatinine.”
The use of race as a factor in measuring GFR has led to controversial results, the researchers wrote.
“There is increased scrutiny around use of race in GFR estimation, including current attention by the United States Congress to algorithms that include race,” they wrote. “The use of Black race in the 2009 CKD-EPI creatinine equation leads to a 16% higher eGFRcr for the same level of creatinine compared to other people.” This could lead to delayed referral for specialist care, dialysis and transplantation, according to the researchers.
“Conversely, omission of the Black race coefficient leads to lower eGFRcr compared to measured GFR and could worsen care because of contraindications to life-saving drugs and contrast-imaging procedures,” they added. “Thus, accurate GFR estimates matter in Black people; there is an urgent need to have more accurate GFR estimating equations that do not require a coefficient for race.”
Inker and colleagues reviewed a pooled data set of seven studies (5,017 participants) and developed new equations to estimate GFR based on the combinations of B2M and BTP. The equations includes patient sets with and without age or sex and race.
The researchers then created a second pooled data set of seven studies (2,245 participants) and showed that “the equation that used all four markers, age and sex, but not race, was as accurate as eGFRcr-cys.”
Specifically, mean measured GFR was 58.1 and 83.2 ml/min/1.73m2 and the proportion of Black patients in the study group was 38.6% and 24% in the development and validation populations, respectively.
“In development, addition of age and sex improved the performance of all equations compared to equations without age and sex, but addition of race did not further improve the performance,” the researchers wrote.
“This is an exciting step toward highly accurate GFR estimates that do not require race, and ultimately any demographic factors,” Inker said in a press release.
“Convenient and accurate ways to estimate kidney function in diverse populations are absolutely critical to increase kidney disease diagnosis rates,” Kerry Willis, PhD, chief scientific officer of the National Kidney Foundation, said in the release. “This new equation is a timely and important advance.”
In an interview with Healio Nephrology, Inker acknowledged that the race-free assessment of GFR will need further study. New biomarkers, she said, are an important step.
Inker is a member of an NKF-ASN task force examining the inclusion of race in the estimation of GFR and its implications for the diagnosis and subsequent management of patients with, or at risk for, kidney diseases. The group is working on a set of recommendations on GFR measurement.
“I think obtaining approval for an assay in the United States is an important step and is doable,” Inker said. Guidelines also can help provide clinicians with practical considerations for determining the right approach to estimating GFR, she said, along with guidelines that consider indications and preferred diagnostic strategies for laboratory testing and reporting panel eGFRs.
“Further studies are required to understand how best to use these equations in clinical practice, especially in diverse clinical settings and geographical locations,” Inker said.
Reference:
www.kidney.org/news/new-study-shows-race-may-not-be-needed-to-accurately-estimate-kidney-function.
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