Study Examines Clinical Implications of Removing Race From eGFR in CKD

A new study published this week demonstrates how altering estimated glomerular filtration rate (eGFR) equations, which use a multiplier to assign higher values to Black patients, would change care recommendations in chronic kidney disease (CKD).

The topic has been under discussion recently and some medical centers have already moved to stop using the multiplier, as inclusion of race has care implications. As higher values indicate better kidney function, there has been increasing recognition that this may lead to inequitable and delayed care in treating CKD. In August, the American Society of Nephrology and the National Kidney Foundation created a joint task force to reevaluate the long-standing use of including race in the calculation to diagnose kidney disease.

GFR is the total volume of filtrate passing through the glomeruli each minute, but that is challenging to assess in real time in a physician’s office. Using serum creatine, factoring in age, height, weight, and gender, gives an estimate.

The 1999 landmark study that proposed the eGFR and included a coefficient for Black patients did so on the basis of 3 flawed, small, poor-quality studies, according to a recent presenter during Kidney Week.

The authors of the current study, published in JAMA, conducted a nationally representative analysis of data from 2001 through 2018 from the National Health and Nutrition Examination Survey to see how removing race as a modifier from the eGFR could alter resulting health care recommendations, which could include making a CKD diagnosis, preventing or delaying CKD progression through the use of blood pressure medication or other interventions, and referrals to a nephrologist and kidney transplant evaluation.

The study included 9522 nonpregnant, self-identified non-Hispanic Black adults (median age, 45 years; 50.5% women). Removing the coefficient for Black race from the calculation of eGFR caused the median eGFR to fall from 102.9 to 88.8 mL/min/1.73 m² (median change, 14.1 mL/min/1.73 m²).

The new estimates revealed by the study showed that removing the modifier, which increased eGFR for Black individuals by nearly 16%, would:

• Increase the crude prevalence of CKD among Black adults by 3.5% to 18.4%.
• Increase the prevalence of Black adults eligible for nephrology specialty care from 3.2% to 3.4%.
• Increase the prevalence of individuals eligible for Medicare coverage for medical nutrition therapy to 5.5% from 5.0%.
• Increase the prevalence of those eligible for kidney disease education from 0.22% to 0.36%.
• Increase the prevalence of Black patients with CKD stage 4 or higher from 1% to 1.3%.

The study also reviewed some of the advantages and disadvantages for Black patients with kidney disease if the modifier is removed. For instance, although the change would increase the percentage of Black patients eligible to join kidney transplant waitlists from 0.66% to 0.71%, it would also reduce the number of patients eligible from donating their kidneys, with an additional 2.1% deemed ineligible.

Besides excluding more donors, the changes could also create “drug contraindications or dose reductions for individuals reclassified to advanced stages of CKD. This potential for benefits and harms must be interpreted in light of persistent disparities in care, documented biases of eGFRcr without race, and the historical misuse of race as a biological variable to further racism,” the authors wrote.

Reference

Diao JA, Wu GJ, Taylor HT, et al. Clinical implications of removing race from estimates of kidney function. JAMA. Published online December 2, 2020. doi:10.1001/jama.2020.22124