The modification of diet in renal disease and chronic kidney disease epidemiology collaboration formulas versus measured or estimated creatinine clearance in kidney transplant recipients.

BACKGROUND: Estimation of glomerular filtration rate (eGFR) after renal transplantation is performed with the use of methods that are standardized for a population of nontransplantation patients with chronic kidney disease. The aim of the study was to compare the performance of GFR estimation formulas in renal transplant recipients.

METHODS: The Modification of Diet in Renal Disease (MDRD) and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) formulas were compared with measured creatinine clearance or clearance estimated by the Cockroft-Gault (C-G) formula. The influence of age, body mass index, and eGFR on the relative performance of these formulas also was studied by subgroups analysis.

RESULTS: Mean measured or estimated creatinine clearance overestimates the values of GFR calculated using the MDRD or CKD-EPI equation. This was statistically significant (P < .05) in whole-study population and in subgroups of patients at age above 25 years, with body mass index above 25, and in a subgroup with eGFR-MDRD <50 mL/min/m(2). The mean bias from creatinine clearance was 7.46 mL/min for MDRD, 4.4 mL/min for CKD-EPI and -1.65 mL/min for C-G formula. There was a statistically significant (P < .05) negative correlation between eGFR value and bias from creatinine clearance for all 3 methods of estimation. The correlation coefficient was -0.4 for MDRD, -0.36 for CKD-EPI, and -0.46 for C-G clearance.

CONCLUSIONS: Measured and estimated creatinine clearance overestimate values of eGFR calculated by the MDRD or CKD-EPI formula in a population of kidney transplant recipients, especially in subjects with obesity and worse renal function. Accuracy of analyzed GFR estimation formulas decreases with deterioration of renal graft function.