Elimination of race in estimates of kidney function to provide unbiased clinical management in Canada

The 2021 Chronic Kidney Disease Epidemiology Collaboration Race-Free Estimated Glomerular Filtration Rate Equations in Kidney Disease: Leading the Way in Ending Disparities

Purpose

In 2020, the National Kidney Foundation (NKF) and the American Society of Nephrology (ASN) convened a Task Force to recommend an evidence-based race-free approach to estimated glomerular filtration rate (eGFR). After the rigorous review of more than 20 approaches, the NKF/ASN Task Force published the final report that recommended the implementation of the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI 2021) equation for eGFR using creatine and expanded utilization of cystatin C testing. The purpose of this manuscript is to provide a comprehensive overview of the evolution of eGFR equations, and an overview of the Task Force deliberations and recommendations. For over two decades, the equation recommended to calculate eGFR included a race coefficient to adjust for data that suggested that American adults with African ancestry had consistently higher serum creatinine levels.

Methods

We will provide a discussion illustrating why the 2021 CKD EPI equations are the most equitable solution to eGFR. We will also provide an overview of the current implementation status and best practices for the new equations. Lastly, we will discuss how deployment of the new equations is an important step toward eliminating significant disparities in CKD care which disproportionately affect communities of color.

Results

Removing race from the algorithm used to assess kidney function is most equitable. Since race is a social construct, its use in clinical algorithms has facilitated health disparities in Black/African American people, Hispanic/Latino people, and other racial and ethnic minority groups-those who are already disproportionately impacted by diabetes, hypertension, and kidney disease. In turn, these same individuals experience significant inequities in kidney health care including reduced access to nephrology care, home dialysis, and kidney transplant.

Conclusions

Adoption of the race-free 2021 CKD-EPI eGFR equations will have life changing implications for kidney health. It will aid in appropriate referral, identification, diagnosis, treatment, and management of kidney disease and transplantation services/options. The outcomes of widespread implementation of the new equations coupled with system change quality improvement interventions such as the kidney profile will lead to more equitable outcomes and begin to address the crippling disparities in early, appropriate testing for CKD.

A Canadian Commentary on the NKF-ASN Task Force Recommendations on Reassessing the Inclusion of Race in Diagnosing Kidney Disease

In 2021, a committee was commissioned by the Canadian Society of Nephrology to comment on the 2021 National Kidney Foundation-American Society of Nephrology Task Force recommendations on the use of race in glomerular filtration rate estimating equations. The committee met on numerous occasions and agreed on several recommendations. However, the committee did not achieve unanimity, with a minority group disagreeing with the scope of the commentary. As a result, this report presents the viewpoint of the majority members. We endorsed many of the recommendations from the National Kidney Foundation-American Society of Nephrology Task Force, most importantly that race should be removed from the estimated glomerular filtration rate creatinine-based equation. We recommend an immediate implementation of the new Chronic Kidney Disease Epidemiology Collaboration equation (2021), which does not discriminate among any group while maintaining precision. Additionally, we recommend that Canadian laboratories and provincial kidney organizations advocate for increased testing and access to cystatin C because the combination of cystatin C and creatinine in revised equations leads to more precise estimates. Finally, we recommend that future research studies evaluating the implementation of the new equations and changes to screening, diagnosis, and management across provincial health programs be prioritized in Canada.

Retaining Race in Chronic Kidney Disease Diagnosis and Treatment

The best overall measure of kidney function is glomerular filtration rate (GFR) as commonly estimated from serum creatinine concentrations (eGFRcr) using formulas that correct for the higher average creatinine concentrations in Blacks. After two decades of use, these formulas have come under scrutiny for estimating GFR differently in Blacks and non-Blacks. Discussions of whether to include race (Black vs. non-Black) in the calculation of eGFRcr fail to acknowledge that the original race-based eGFRcr provided the same CKD treatment recommendations for Blacks and non-Blacks based on directly (exogenously) measured GFR. Nevertheless, the National Kidney Foundation and the American Society of Nephrology Task Force on Reassessing the Inclusion of Race in Diagnosing Kidney Disease removed race in CKD treatment guidelines and pushed for the immediate adoption of a race-free eGFRcr formula by physicians and clinical laboratories. This formula is projected to negate CKD in 5.51 million White and other non-Black adults and reclassify CKD to less severe stages in another 4.59 million non-Blacks, in order to expand treatment eligibility to 434,000 Blacks not previously diagnosed and to 584,000 Blacks previously diagnosed with less severe CKD. This review examines: 1) the validity of the arguments for removing the original race correction, and 2) the performance of the proposed replacement formula. Excluding race in the derivation of eGFRcr changed the statistical bias from +3.7 to -3.6 ml/min/1.73m2 in Blacks and from +0.5 to +3.9 in non-Blacks, i.e., promoting CKD diagnosis in Blacks at the cost of restricting diagnosis in non-Blacks. By doing so, the revised eGFRcr greatly exaggerates the purported racial disparity in CKD burden. Claims that the revised formulas identify heretofore undiagnosed CKD in Blacks are not supported when studies that used kidney failure replacement therapy and mortality are interpreted as proxies for baseline CKD. Alternatively, a race-stratified eGFRcr (i.e., separate equations for Blacks and non-Blacks) would provide the least biased eGFRcr for both Blacks and non-Blacks and the best medical treatment for all patients.

Is the use of the new Chronic Kidney Disease Epidemiology Consortium (CKD-EPI 2021) formula appropriate for the Spanish population?

INTRODUCTION

United States nephrology societies recommend changing from the CKD-EPI 2009 equation to the new CKD-EPI 2021 equation, which does not include the race coefficient, for calculating estimated glomerular filtration rate (eGFR). It is unknown how this change might affect the distribution of kidney disease in the predominantly Caucasian Spanish population.

METHODS

Two databases of adults from the province of Cádiz, DB-SIDICA (N=264,217) and DB-PANDEMIA (N=64,217), that had plasma creatinine measurements recorded between 2017 and 2021 were studied. Changes in eGFR and the consequent reclassification into different categories of the KDIGO 2012 classification resulting from substituting the CKD-EPI 2009 equation for the 2021 equation were calculated.

RESULTS

Compared to the 2009 equation, CKD-EPI 2021 yielded a higher eGFR, with a median of 3.8mL/min/1.73m² (IQR 2.98-4.48) in DB-SIDICA and 3.89mL/min/1.73m² (IQR 3.05-4.55) in DB-PANDEMIA. The first consequence was that 15.3% of the total population in DB-SIDICA and 15.1% of the total population in DB-PANDEMIA were reclassified into a higher category of eGFR, as were 28.1% and 27.3%, respectively, of the population with CKD (G3-G5); no subjects were classified into the more severe category. The second consequence was that the prevalence of kidney disease decreased from 9% to 7.5% in both cohorts.

CONCLUSIONS

Implementing the CKD-EPI 2021 equation in the Spanish population, which is predominantly Caucasian, would increase eGFR by a modest amount (greater in men and those who are older or have a higher GFR). A significant proportion of the population would be classified into a higher eGFR category, with a consequent decrease in the prevalence of kidney disease.