How should I estimate glomerular filtration rate in an African‑American patient without using race‑based equations?

GFR Estimation in African-American Patients Without Race-Based Equations

Use the 2021 CKD-EPI creatinine equation without the race variable (CKD-EPIcr_R) for all African-American patients immediately. 1, 2

Primary Recommendation: The Race-Free CKD-EPI 2021 Equation

The NKF-ASN Task Force issued a strong recommendation in 2022 that the CKD-EPI creatinine equation refit without race (CKD-EPIcr_R) should be implemented immediately across all U.S. laboratories for adults. 1 This approach:

• Eliminates systematic bias that previously assigned African-American patients higher eGFR values, which delayed CKD diagnosis, nephrology referrals, and transplant eligibility 2
• Maintains acceptable performance across diverse populations while reducing differential bias between Black and non-Black individuals 1, 2
• Is immediately available to all laboratories without requiring new assays or infrastructure 1

Confirmatory Testing Strategy

For patients at risk for or with established CKD, add cystatin C measurement and use the 2021 CKD-EPI creatinine-cystatin C equation (CKD-EPIcr-cys_R) without race. 1, 2

Why Cystatin C Matters

• Combining creatinine and cystatin C is more accurate than either marker alone and eliminates the need for race-based adjustments 1
• Cystatin C-based equations (CKD-EPIcys and CKD-EPIcr-cys_R) generate statistically unbiased and accurate estimates in Black participants without requiring race specification 3
• Particularly valuable in patients with low muscle mass where creatinine-based estimates are less reliable 2

The Task Force specifically recommends national efforts to facilitate increased, routine, and timely use of cystatin C for confirmatory testing. 1

Critical Implementation Points

What NOT to Do

Do not report dual eGFR values (one with race, one without) or label them as "high muscle mass" versus "low muscle mass"—the Task Force found no evidentiary basis for this practice, which adds subjectivity and confusion. 2

Laboratory Reporting

• Report eGFR using the race-free 2021 CKD-EPI equation 1, 2
• Include serum creatinine values extending to 2 decimal places 1
• Note that "use of nonindexed eGFR values (mL/min) should be considered for drug dosing decisions" 1
• For patients with obesity, consider deindexing GFR for medication dosing, as indexed eGFR approaches may underestimate measured GFR 1

Clinical Impact on African-American Patients

Removing race from eGFR calculations will:

• Identify approximately 434,000 additional Black adults with eGFR <60 mL/min/1.73 m² who were previously undiagnosed 4
• Increase nephrology referrals by approximately 260,000 Black adults (26% increase) who now meet referral thresholds 2
• Expand transplant eligibility by approximately 290,000 Black adults (29% increase) 2
• Enable earlier initiation of kidney-protective medications (ACE inhibitors, ARBs, SGLT2 inhibitors) 2

Addressing Concerns About Single eGFR Values

Do not rely on a single eGFR result for major clinical decisions. 1

Instead:

• Monitor trends in eGFR values over time, which may require more frequent testing 1
• Incorporate other clinical information including assessment for albuminuria (as recommended by KDIGO CKD guidelines) 1
• Use confirmatory testing with cystatin C-based equations or clearance measurements for important decisions 1, 2
• Consider direct GFR measurement using exogenous filtration markers when precision is critical 1

Evidence Quality and Nuances

The systematic review evidence shows that removal of race adjustment improved bias, accuracy, and precision of eGFR equations for Black adults in the majority of international studies. 5 However, one dissenting perspective argues that removing race changes statistical bias from +3.7 to -3.6 mL/min/1.73 m² in Blacks, potentially promoting overdiagnosis. 4

The guideline consensus strongly favors race-free equations because the previous race-based approach created systematic disadvantages for Black individuals in accessing nephrology care, transplant evaluation, and kidney-protective therapies—outcomes that directly impact morbidity and mortality. 1, 2 The Task Force explicitly prioritized reducing differential bias and promoting health equity over maintaining the statistical properties of older equations. 1

Assay Considerations

Encourage clinical laboratories to:

• Discontinue Jaffe reaction assays for serum creatinine in favor of enzymatic reaction assays to reduce variability and increase eGFR accuracy 1
• Standardize cystatin C assays to support wider implementation of confirmatory testing 1