Improved glomerular filtration rate estimation using New equations combined with standardized cystatin C and creatinine in Chinese adult chronic kidney disease patients

The newly developed glomerular filtration rate (GFR)-estimating equations developed by the CKD-EPI Collaboration and Feng et al. (2013) that are based on standardized serum cystatin C (ScysC), combined/not combined with serum creatinine (Scr), require further validation in China. We compared the performance of four new equations (CKD-EPIcys, CKD-EPIcr-cys, Fengcys, and Fengcr-cys equations) with the CKD-EPI creatinine equation (CKD-EPIcr) in adult Chinese chronic kidney disease (CKD) patients to clarify their clinical application. GFR was measured using the dual plasma sampling 99mTc-DTPA method (mGFR) in 252 adult CKD patients enrolled from four centres. Scr and ScysC were measured by standardized assays in a central laboratory. Each equation's performance was assessed using bias, precision, accuracy, agreement, and correct classification of the CKD stage. The measured GFR was 46 [25–83] mL/min per 1.73m2. The CKD-EPIcys, CKD-EPIcr-cys and Fengcys equations provided significantly higher accuracy (P15: 38.9%, 39.7%, and 38.9%) than the CKD-EPIcr equation (29.8%). The CKD-EPIcr-cys and Fengcr-cys equations presented higher precision (IQR of the difference, 16.4 and 17.3mL/min per 1.73m2, respectively) and narrower acceptable limits in Bland–Altman analysis (56.6 and 50.8mL/min per 1.73m2, respectively) than single marker-based equations. The CKD-EPIcr-cys equation achieved the highest overall correct proportion (61.5%) in classification of CKD stages. Combining ScysC and Scr measurements for GFR estimation improves diagnostic performance. The Scr–ScysC equation showed better performance than equations based on either marker alone. The CKD-EPIcr-cys equation showed the best performance for GFR estimation in Chinese adult CKD patients. •Clearance of dual plasma sampling 99mTc-DTPA was used to measure GFR (mGFR).•Two new Chinese-based eGFR equations were compared with the new CKD-EPI equations.•Two combined equations provided better performance than the SCr or ScysC equations.•The CKD-EPIcr-cys equation showed the best performance in adult CKD patients.