Prospective Comparison of Equations Based on Creatinine and Cystatin C for the Glomerular Filtration Rate Estimation...

Currently, there is no dedicated equation to estimate glomerular filtration rate (GFR) for transplanted kidneys. This study aimed to compare the performance of serum creatinine (Scr)- and cystatin C (CysC)-based equations in Chinese renal transplant recipients.

A total of 252 stable renal transplant recipients were enrolled in this study. The plasma clearance of ^99mTc-DTPA (rGFR) was used as a reference standard. The Scr, CysC, and rGFR of the patients were measured on the same day. The bias, precision, accuracy (percentage of estimates within 10%, 30%, and 50% of rGFR), and agreements of 8 Scr and 5 CysC eGFR equations were assessed. The factors affecting the accuracy were also evaluated.

Among the Scr-based equations, the Japanese Society of Nephrology-Chronic Kidney Disease Initiatives (JSN-CKDI) equation had the best overall performance with a bias of -6.2 mL/min/1.73 m², and 96.1% of its estimates were within 30% of the rGFR. For the CysC-based equations, the Filler equation had the best performance with a bias of -3.9 mL/min/1.73 m², and 93.7% of its estimates were within 30% of the rGFR. Overall, the CysC-based equations showed better performance than the Scr-based equations. In addition, significant differences were observed between bias and gender and between bias and rGFR value in some equations, whereas transplantation time and immunosuppressive regimens were not correlated with the bias.

The JSN-CKDI equation provides the best estimation of the GFR equations, and the CysC-based equations performed better than the Scr-based equations in this population.