Comparisons between the 2012 New CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) Equations and Other Four Approved Equations

OBJECTIVE: The Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) reported two equations in 2012: one based on cystatin C concentration (CKD-EPI(2012cys)) and the other using both serum creatinine and cystatin C concentrations (CKD-EPI(2012Scr-cys)). We compared the adaptability of new formulae with other four equations. METHODS: Participants (n = 788; median age, 54 [range, 19–94] years) were recruited from the First Affiliated Hospital of Nanjing Medical University. The reference glomerular filtration rate (rGFR) was measured by a( 99)mTc-DTPA renal dynamic imaging method, and the estimated glomerular filtration rate (eGFR) was calculated separately by the Chinese adapted Modification of Diet in Renal Disease equation (C-MDRD), MacIsaac, Ma, serum creatinine-based CKD-EPI equation (CKD-EPI(2009Scr)), CKD-EPI(2012cys) and CKD-EPI(2012Scr-cys) equations. We compared the performance of six equations with rGFR. RESULTS: Median rGFR was 76.35 (interquartile range, 59.03–92.50) mL/min/1.73 m(2). Compared with CKD-EPI(2009Scr), CKD-EPI(2012Scr-cys) formula had better diagnostic value with larger area under the receiver operating characteristic curve (ROC(AUC), 0.879, p = 0.006), especially in young participants (ROC(AUC), 0.883, p = 0.005). CKD-EPI(2012cys) equation did not perform better than other available equations. Accuracy (the proportion of eGFR within 30% of rGFR [P(30)]) of the CKD-EPI(2012Scr-cys) equation (77.03%) was inferior only to MacIsaac equation (80.2%) in the entire participants, but performed best in young participants with normal or mildly-injured GFR. Neither of the two new CKD-EPI equations achieved any ideal P(30) in the elderly participants with moderately-severely injured GFR. Linear regression analysis demonstrated a consistent result. In this study, CKD-EPI(2012Scr-cys) had a relatively better diagnosis consistency of GFR stage between the eGFR and rGFR in the whole cohort. CONCLUSION: CKD-EPI(2012Scr-cys) appeared less biased and more accurate in overall participants. Neither of the new CKD-EPI equations achieved ideal accuracy in senior participants with moderately-severely injured GFR. A large-scale study with more subjects and cooperating centers to develop new formulae for the elderly is assumed to be necessary.