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 (FASCr-Cys or FASCys). We compared the performance and assessed the applicability of the new FAS equation with the 2012 CKD-EPI (CKD-EPICys and CKD-EPICr-Cys) equation in Chinese subjects.

Methods: A total of 1184 patients, mean aged 55.06 year who underwent 99mTc-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-EPICr-Cys or the FASCr-Cys. Detailedly, referred to rGFR (67.33 ml/min/1.73 m2), the CKD-EPICys, CKD-EPICr-Cys, FASCys, and the FASCr-Cys estimated GFR 56.46 ml/min/1.73 m2, 62.79 ml/min/1.73 m2, 56.45 ml/min/1.73 m2, and 61.04 ml/min/1.73 m2, gave ROCAUC0.944, 0.954, 0.943, and 0.953, respectively. Another comparison as to bias, precision, P30, and RMSE with FASCr-Cys were - 2.87 ml/min/1.73 m2, 19.01 ml/min/1.73 m2, 74.16%, and 17.84 ml/min/1.73 m2 showed that FASCr-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 m2 subgroup, the FASCr-Cys equation showed the best performance. In older subjects, compared with FASCys, CKD-EPICr-Cys, and CKD-EPICys, the FASCr-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, P30 was statistically different from the other equations, and achieved a ideal value > 70%.

Conclusions: The performance of the FASCr-Cys equation is better than that of the CKD-EPICr-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.