What is the recommended chronic kidney disease screening protocol for African‑American adults, including the age to start, risk factors, and the race‑neutral estimated glomerular filtration rate (eGFR) equation to use?

CKD Screening Protocol for African-American Adults Using Race-Neutral eGFR

All U.S. clinical laboratories should immediately implement the 2021 CKD-EPI creatinine equation without any race variable for estimating GFR in African-American adults and all other patients. 1

Race-Neutral eGFR Equation to Use

Primary equation: The 2021 CKD-EPI creatinine equation (race-free) should be adopted as the standard first-line test for all adults, replacing any race-based formulas. 1, 2 This equation:

• Uses only age, sex, and serum creatinine—race is completely excluded from both calculation and reporting. 2
• Maintains acceptable performance characteristics across diverse populations while eliminating systematic bias against Black individuals. 1, 3
• Is readily available to all laboratories without requiring new assays or infrastructure changes. 2

Confirmatory testing: For patients at risk for or with established CKD, add cystatin C measurement and apply the 2021 CKD-EPI creatinine-cystatin C equation (also race-free). 1, 2 The combined creatinine-cystatin C equation:

• Provides greater accuracy than either marker alone and further reduces differential bias between Black and non-Black individuals. 1, 3
• Is especially valuable when creatinine-based estimates may be unreliable (e.g., patients with low muscle mass). 2

Age to Start Screening

While the provided guidelines focus on equation implementation rather than screening initiation age, standard CKD screening protocols apply:

• Screen African-American adults with diabetes, hypertension, cardiovascular disease, or family history of kidney disease starting at diagnosis of these conditions. 2
• For asymptomatic African-Americans without risk factors, follow general population screening guidelines, though the race-free equations will now identify kidney disease earlier than race-based formulas did. 4

Key Risk Factors Warranting Screening

African-Americans face disproportionate CKD burden and should be screened when they have:

• Diabetes or hypertension—the most common causes of CKD that disproportionately affect Black communities. 4
• Cardiovascular disease, which shares bidirectional risk with kidney disease. 4
• Family history of kidney disease, particularly ESKD or genetic kidney disorders. 4
• Obesity, which increases CKD risk and may require de-indexed eGFR for medication dosing. 2

Critical Implementation Points

What laboratories must do:

• Report eGFR using the race-free 2021 CKD-EPI equation as the single value. 2
• Display serum creatinine to two decimal places for improved precision. 2
• Never report dual eGFR values (one with race, one without) or label them as "high/low muscle mass"—the Task Force found no evidentiary basis for this practice, which adds subjectivity and perpetuates bias. 1, 2
• Transition from Jaffe reaction assays to enzymatic assays for serum creatinine to reduce variability. 2
• Standardize cystatin C assays to facilitate broader confirmatory testing. 2

What clinicians must do:

• Do not base major clinical decisions on a single eGFR result; confirm with repeat testing over time. 2
• Monitor eGFR trends longitudinally rather than relying on isolated values. 2
• Incorporate albuminuria assessment alongside eGFR for comprehensive CKD staging. 2
• Use non-indexed eGFR values (mL/min, not mL/min/1.73 m²) when making drug-dosing decisions. 2
• For critical decisions (transplant evaluation, chemotherapy dosing), use confirmatory cystatin C testing or direct GFR measurement with exogenous filtration markers. 2

Clinical Impact of Race-Free Equations

Benefits for African-American patients:

The race-free approach eliminates systematic disadvantages that delayed diagnosis and treatment for Black individuals under the old race-based system. 2, 4 Specifically:

• Approximately 2 million Black adults will be reclassified as having CKD who were previously missed by race-based equations. 2
• 290,000 more Black adults (a 29% increase) will meet thresholds for kidney transplant referral. 2
• 260,000 more Black adults will meet criteria for nephrology referral, enabling earlier specialist care. 2
• More Black patients will qualify for kidney-protective medications (ACE inhibitors, ARBs, SGLT2 inhibitors) at appropriate disease stages. 2

The old race-based equation systematically overestimated kidney function in Black patients by including a race coefficient that increased eGFR by approximately 16%, delaying diagnosis and access to life-saving interventions. 3, 5

Common Pitfalls to Avoid

Do not simply remove the race coefficient from the old 2009 CKD-EPI equation. This would cause systematic underestimation of GFR in Black patients (median 7.1 mL/min/1.73 m² too low) and create new harms. 3 The 2021 equation was specifically refit without race using diverse populations to maintain accuracy. 3

Do not assume all race-free equations perform equally. The creatinine-only race-free equation has larger intraindividual discordance in Black versus non-Black patients compared to the creatinine-cystatin C combination. 6 When precision matters most, use the combined equation. 3

Recognize that eGFR equations have inherent imprecision. In validation studies, approximately 15% of eGFR values fall outside 30% of measured GFR regardless of race. 3 This underscores why confirmatory testing and longitudinal monitoring are essential for major clinical decisions. 2

Evidence Strength and Rationale

The NKF-ASN Task Force recommendation represents the strongest available guideline evidence (2022), issued jointly by the two leading U.S. nephrology organizations after rigorous evaluation of 26 different approaches. 1 The Task Force explicitly prioritized reducing differential bias and promoting health equity over preserving statistical properties of older equations. 2

The 2021 race-free equations were developed and validated in diverse cohorts (31.5-39.7% Black participants) totaling over 13,000 individuals, with external validation in an additional 4,050 participants. 3 These equations maintain accuracy while eliminating the biologically implausible use of race as a proxy for unmeasured physiologic differences. 7, 5

Race is a social construct without biological basis for kidney function estimation, and its inclusion in clinical algorithms has perpetuated health disparities. 4, 7 The race-free approach aligns with the fundamental principle that clinical tools should not systematically disadvantage any racial group. 1