A comparison between 2017 FAS and 2012 CKD-EPI equations: a multi-center validation study in Chinese adult population

Background The recent guidelines recommend using the estimated glomerular filtration rate (eGFR) to evaluate renal function. There are two reported full-age-spectrum (FAS) equations in 2017, which are based on serum cystatin C concentrations with or without accompanying serum creatinine level (FAS Cr–Cys or FAS Cys ). We compared the performance and assessed the applicability of the new FAS equation with the 2012 CKD-EPI (CKD-EPI Cys and CKD-EPI Cr–Cys ) equation in Chinese subjects. Methods A total of 1184 patients, mean aged 55.06 year who underwent 99m Tc-DTPA GFR measurements (rGFR) from four hospitals were enrolled. The bias (eGFR-rGFR), precision (interquartile range of difference [IQR]), and accuracy (the proportion of eGFR within 30% of rGFR [P30]) of eGFR and rGFR calculated by four equations were compared. Results Generally, the equation based on the combination of Cys and Scr performed superior to that on the basis of Cys alone, either the CKD-EPI Cr–Cys or the FAS Cr–Cys . Detailedly, referred to rGFR (67.33 ml/min/1.73 m 2 ), the CKD-EPI Cys , CKD-EPI Cr–Cys , FAS Cys , and the FAS Cr–Cys estimated GFR 56.46 ml/min/1.73 m 2 , 62.79 ml/min/1.73 m 2 , 56.45 ml/min/1.73 m 2 , and 61.04 ml/min/1.73 m 2 , gave ROC AUC 0.944, 0.954, 0.943, and 0.953, respectively. Another comparison as to bias, precision, P 30 , and RMSE with FAS Cr–Cys were − 2.87 ml/min/1.73 m 2 , 19.01 ml/min/1.73 m 2 , 74.16%, and 17.84 ml/min/1.73 m 2 showed that FAS Cr–Cys performed approximately more accurate than other equations, as well as the diagnostic consistency of GFR staging. In the rGFR < 60 ml/min/1.73 m 2 subgroup, the FAS Cr–Cys equation showed the best performance. In older subjects, compared with FAS Cys , CKD-EPI Cr–Cys , and CKD-EPI Cys , the FAS Cr–Cys equation had relatively less bias (− 8.09 vs. − 9.63, − 7.52, − 11.04, P < 0.05), most precise (15.18 vs. 16.32, 15.22, 16.63), and most accuracy, P 30 was statistically different from the other equations, and achieved a ideal value > 70%. Conclusion The performance of the FAS Cr–Cys equation is better than that of the CKD-EPI Cr–Cys equation in the Chinese population, particularly in the elderly. Yet, further modification of FAS equations from a large-scale study could be more suitable for the Chinese population, particularly in older people.