New and old GFR equations: a European perspective

Area of Science:

• Nephrology
• Clinical Chemistry
• Biomarker Development

Background:

• Glomerular filtration rate (GFR) estimation is crucial for diagnosing and managing kidney disease.
• Current creatinine-based equations, like CKD-EPI2009 and CKD-EPIcr2021, exhibit significant limitations, including age-related overestimation and racial/ethnic biases.
• Recalibration of CKD-EPIcr2021 did not resolve performance issues across diverse populations.

Purpose of the Study:

• To evaluate the performance of the European Kidney Function Consortium (EKFC) creatinine-based equation (EKFC) and cystatin C-based equation (EKFC_CC) compared to CKD-EPI equations.
• To assess the ability of the EKFC equations to provide a continuous GFR estimation across pediatric and adult care transitions.
• To determine the accuracy of EKFC equations in diverse racial and ethnic groups.

Main Methods:

• Comparative analysis of GFR estimation equations: CKD-EPI2009, CKD-EPIcr2021, EKFC, and EKFC_CC.
• Evaluation of equation performance across different age groups, particularly the transition from pediatric to adult care.
• Assessment of equation accuracy in various racial and ethnic populations, including White Europeans, Black Europeans, and Black Africans.

Main Results:

• CKD-EPI equations, including the recalibrated CKD-EPIcr2021, demonstrate significant overestimation in young adults and exhibit racial/ethnic biases.
• The EKFC equation shows improved performance and continuity of eGFR estimation, particularly at the pediatric-adult transition.
• The EKFC_CC equation, being sex- and race-free, outperforms the CKD-EPI cystatin C equation and shows promise for equitable GFR estimation.

Conclusions:

• The EKFC equations represent a significant advancement in GFR estimation, addressing key limitations of existing CKD-EPI models.
• EKFC equations offer more accurate and equitable GFR estimates across diverse populations and age groups.
• Despite improvements, precise GFR measurement via exogenous clearance remains necessary for specific clinical scenarios.