New research sheds light on impact of recent eGFR updates

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New research indicates that removing a race modifier from a formula used to diagnose kidney disease—estimated glomerular filtration rate (eGFR)—could lead to more equitable care for Black patients. This study and a second examining how this same diagnostic approach impacts Asian patients were presented at the 2022 American Association for Clinical Chemistry (AACC) annual scientific meeting and clinical lab expo (24–28 July, Chicago, USA).

One of the most established ways to diagnose kidney disease is by measuring eGFR with a mathematical formula. Race has long been used as a variable in eGFR equations because researchers and clinicians mistakenly believed that Black people have higher muscle mass and/or creatinine metabolism than white people, as per an AACC press release.

The formula most widely used to determine eGFR, the Chronic Kidney Disease Epidemiology Collaboration equation (CKD-EPI), includes variables for serum creatinine, gender, race and age. However, following a joint announcement from last year, the National Kidney Foundation (NKF) and the American Society of Nephrology (ASN) now recommend that clinical laboratories use a revised CKD-EPI refit formula developed for assessing kidney function that does not include a race modifier. Two studies discussed at AACC 2022 set out to determine how effective this new formula is.

Impact on CKD staging

Researchers at the University of Texas (UT) Southwestern Medical Center and Parkland Health (Dallas, USA)—led by Ibrahim Hashim—examined serum creatinine values of 56,676 patients over a 16-month timeframe, and estimated eGFR using the previous CKD-EPI formula and the new CKD-EPI refit formula. After removing the race adjustment, 14% to 28% of Black patients were reclassified into a more severe chronic kidney disease (CKD) stage.

Based on these results, the researchers support removing race as a factor in eGFR equations, noting that it perpetuates systemic racism and discrimination in healthcare, and that its removal will provide more equitable care and reduce healthcare disparities. UT Southwestern began using the new formula in May, according to Hashim.

“Race is a social construct,” he said. “By removing race as a variable, patients are now objectively classified, which opens access for additional testing and more investigation into their condition. This can only lead to better care for patients with CKD. This is very significant, because we know there is racial disparity in healthcare. By removing race as a factor, medicine becomes more personalised.”

Accuracy of the new eGFR equation

Researchers at several different medical schools and hospitals in Korea also assessed the new 2021 CKD-EPI equation in a Korean population—as very few studies have evaluated the new equation’s performance in Asian patients, the AACC release notes.

The researchers compared eGFR results from 1,899 people with results from chromium-51-ethylenediamine tetraacetic acid GFR measurements (the gold standard for determining GFR). They found that the mean bias of the 2021 CKD-EPI refit formula was significantly greater than that of the original CKD-EPI formula when comparing test results for both males and females.

This means that “additional research is needed to decide whether to apply the 2021 CKD-EPI equation in clinical practice” with Asian patients, said Tae-Dong Jeong (Ewha Womans University College of Medicine, Seoul, South Korea), the lead author of the study.

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