Application of serum cystatin C-based eGFR equations in renal function evaluation for kidney transplant recipients

Abstract

Objective To compare the differences of the four estimating equations about MDRD, CKD-EPI eGFRcr, CKD-EPI eGFRcys, and eGFRcr-cys in evaluating the renal function of kidney transplant recipients, and explore the optimal equations to estimate the renal allograft function. Method Between January 2000 to March 2015, a total of 213 renal transplant recipients with data integrity were enrolled. eGFR was calculated using the equations: Modification of Diet in Renal Dis-ease [eGFR (MDRD), the creatinine-based equation (CKD-EPI eGFRcr), the CKD EPI cystatin C equation (CKD-EPI eGFRcys), and CKD EPI creatinine + cystatin C equation (CKD-EPI eGFRcr-cys) drafted by Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) in 2009 and 2012. We assessed the performance of these four eGFR equations by Pearson correlation analysis, Bland-Altman plot, and Cox regression analysis. Result The incidence of reduced kidney function was 49.3% using MDRD, 43.7% using eGFRcr, 49.8% using eGFRcys, and 52.1% using eGFRcr-cys, respectively. In recipients with eGFR ≥60 ml·min·1.73 m2 estimated by MDRD, 19.5% and 11% had eGFR <60 ml·min·1.73 m2 re-estimated by eGFRcys and eGFRcr-cys respectively. Serum cystatin C was significantly correlated with serum creatinine, MDRD, eGFRcr, eGFRcr-cys with the correlation coefficient being 0.67, 0.61, 0.65, and 0.77 respectively. Only the CKD staging based on eGFRcr, and eGFRcr-cys was positively related to renal graft loss risk. eGFRcr, and eGFRcr-cys could not be replaced each other, and only eGFRcr-cys showed strong correlation with the other three equations. Conclusion As compared with others, eGFR (CKD-EPI-Creat+ CysC) is more precise in estimating GFR and evaluating the renal graft loss risk. Key words: Kidney transplantation; Cystatin C; Glomerular filtration rate