Performance of Creatinine and Cystatin C-Based Equations to Estimate Kidney Function in Renal Transplant Recipients

 Numerous equations are applied in order to estimate the glomerular filtration rate (GFR).

 This study aimed to spot the optimal equation that accurately estimates GFR and, therefore, the chronic kidney disease (CKD) stage in renal transplant patients.

 This cross-sectional study was conducted on 58 renal transplant patients. Their venous blood samples were obtained for serum creatinine and cystatin C determination used to calculate estimated GFR (eGFR). The average contrast of GFR in each equation was calculated using the Bland-Altman method. The correlation, bias, imprecision, and 10% and 30% accuracy were compared between the eGFR cystatin C and creatinine. Concordance between both equations for CKD staging was assessed. The classification of patients was also investigated.

 Bland-Altman plots and bias demonstrated that eGFR by the abbreviated modification of diet in renal disease (Ab-MDRD) was the most accurate compared with chronic kidney disease epidemiology collaboration (CKD-EPI) cystatin C, followed by CKD-EPI eGFR creatinine. With reference to CKD-EPI cystatin C, the imprecision of the equations was approximately similar to Ab-MDRD, and CKD-EPI creatinine is still better than the Cockcroft-gault (CG) formula. They also showed good 30% accuracy. Finally, our finding suggested that Ab-MDRD and CKD-EPI eGFR creatinine might be the best-performing equation in the classification of the CKD stages in a cutoff of 60 mL/min/1.73 m2.

 Due to the high cost and potential delay in measuring cystatin C, it would be much more appropriate to measure Ab-MDRD; after that, CKD-EPI eGFR creatinine as an alternative approach in order to facilitate rapid clinical decision in renal transplant patients.