Utility of Estimated Glomerular Filtration Rate Equations in Assessing Renal Allograft Function: Are They Accurate?

Creatinine clearance (CrCl) is more accurate than other methods when assessing renal allograft function, but it is inconvenient for patients. In clinical practice, renal allograft function is often estimated using estimated glomerular filtration rate (GFR) equations. This cross-sectional study compared agreement between CrCl and serum creatinine-based equations among renal transplant recipients (RTRs) attending a transplant clinic in a tertiary center. Six equations (Cockcroft-Gault, Walser's, Nankivell, abbreviated Modification of Diet in Renal Disease [MDRD], Chronic Kidney Disease Epidemiology Collaboration [CKD-EPI], and European Kidney Function Consortium[EKFC]) were included in the analysis. The bias, precision, and accuracy of each equation were determined. Correlation analysis was performed by determining the correlation coefficient and plotting Bland-Altmann plots. A total of 165 subjects were included in this study. Mean serum creatinine was 112.03 ± 38.67 µmol/L, and mean CrCl was 58.44 ± 21.24 mL/min/1.73 m. Walser's equation showed strongest correlation, lowest bias, and highest accuracy of the proportion of estimated GFR falling within ±30% of CrCl, followed by the 4-variable MDRD equation. All 6 equations systematically underestimated GFR among RTRs. Walser's equation showed the best estimation of GFR, suggesting that it may be the formula of choice to estimate GFR among RTRs.