The Xiangya equation could not replace the Asian modified CKD-EPI equation in estimating glomerular filtration rate in Chinese patients with chronic kidney disease.

BACKGROUND: To evaluate the clinical practicability of the Xiangya equation in estimating glomerular filtration rate (GFR) and compare with the Asian modified Chronic Kidney Disease-Epidemiology Collaboration (CKD-EPI) equation, assessing whether the Xiangya equation could replace the Asian modified CKD-EPI equation as the preferred method for predicting GFR in the Chinese CKD patients in an external validation study. METHODS: The GFR was determined simultaneously by two methods: (a) the Asian modified CKD-EPI equation (GFRCKD-EPI); (b) the Xiangya equation (GFRXiangya); diagnostic performance of the two models was compared by the regression analysis, the Bland-Altman plot, bias, precision and P30 under the background of 99mTc-diethylenetriaminepentaacetic acid (99mTc-DTPA) dual plasma sample clearance method as reference method for GFR measurement (mGFR). RESULTS: A total of 158 Chinese CKD patients were included in our external study. The GFRXiangya was highly related with mGFR, with the correlation coefficient of 0.92. The regression equation was GFRXiangya = 0.55*mGFR + 28.25, where the regression coefficient was far away from one and the intercept was wide. Compared with the Asian modified CKD-EPI equation, the performance of the Xiangya equation demonstrated a poorer bias (9.5 vs - 3.3 ml/min/1.73 m2, P < 0.001), an inferior precision (23.9 vs 13.0 ml/min/1.73 m2, P < 0.001), a lower P30 (51.3% vs 73.4%, P < 0.001) and a wider 95% limit of agreement in Bland-Altman analysis (65.0 vs 44.9 ml/min/1.73 m2). CONCLUSION: Due to relatively inferior performance, the Xiangya equation could not replace the Asian modified CKD-EPI equation in estimating GFR in Chinese patients with chronic kidney disease in our external cohort.