Recalibration of the European Kidney Function Consortium eGFR Equation for the Indian Population

The new European Kidney Function Consortium (EKFC) eGFR equation uses rescaled serum creatinine (SCr) to an age- and sex-specific normal median value, making it applicable across the entire age spectrum. We evaluated the performance of the recalibrated EKFC_crea equation using Indian-specific Q (for median SCr) and K (for normal glomerular filtration rate [GFR]) in a large Indian cohort and the ability to correctly classify chronic kidney disease (CKD).

Indian adults (healthy and patients with CKD) were recruited. Plasma iohexol clearance was used to assess measured GFR (mGFR). Indian-specific Q values were derived from healthy individuals, and K from those under the age of 40 years. We evaluated EKFC_crea, CKD- Epidemiology Collaboration (EPI)₂₀₂₁, and recalibrated the EKFC_crea equations, incorporating the Indian Q (ISQ), Indian constant (ISK), and both (ISQ + ISK). We evaluated bias and accuracy (P₃₀) for all equations.

A total of 1174 participants (615 healthy, 559 CKD), mean age 48 years, with equal sex distribution were recruited. The EKFC_crea equation showed a mean bias of 9.9 (95% CI: 8.7- 11.1) ml/min per 1.73 m² with P₃₀; 58.1%. EKFC_ISQ reduced bias to 4.9 (95% CI: 3.7 6.0) ml/min per 1.73 m² and improved P₃₀ to 64%. EKFC_ISK achieved a bias of -1.2 (95% CI: -0.1 to -2.2) ml/min per 1.73 m² and P₃₀ of 69%. 30%, 48%, and 67% of CKD patients were categorized into lower categories using the EKFC_ISQ, EKFC_ISK, and EKFC_ISQ+ISK equations, respectively, against the CKD-EPI ₂₀₂₁.

Recalibrating EKFC_crea with Indian-specific Q and K reduced bias and improved accuracy, with EKFC_ISK emerging as the best model. Adopting this recalibrated equation in clinical practice and public health initiatives after validation in diverse cohorts could lead to more accurate CKD diagnosis and staging in India.