Objective: To assess the performance of the full age spectrum (FAS) equation in comparison to other equations in subjects with chronic kidney disease (CKD) for the first time in China.
Materials and methods: The measured glomerular filtration rate (mGFR) obtained by the 99mTc-diethylenetriamine pentaacetic acid renogram was used as the reference standard. Bias, precision, and accuracy were analyzed to identify which of these four equations performed better: FAS equation, the Modification of Diet in Renal Disease (MDRD) equation, the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation and the Berlin Initiative Study-1 (BIS-1) equation. κ-test and the Bland-Altman method were applied to evaluate the classification and the agreement between the estimated glomerular filtration rate (eGFR) and mGFR, respectively.
Results: 396 subjects were enrolled in this study. The precision (root mean square error, RMSE) of the FAS equation was 19.49 (95% CI 17.98, 21.27) in adults (18 - 70 years) and 14.06 (95% CI 12.50, 16.07) in older adults (≥ 70 years), better than the corresponding values of MDRD equation 22.32 (95% CI 20.59, 24.36) and 20.76 (95% CI 18.46, 23.72)(p < 0.05), superior to 17.59 (15.64, 20.10) for CKD-EPI equation in older adults, respectively. The FAS equation showed the least bias (1.28 (95% CI -1.38, 4.03)) in older adults and the highest percentage (63.64%) of accuracy (30%) in all participants. The FAS correctly classified subjects into GFR categories.
Conclusion: The FAS equation improved the precision and accuracy of eGFR, especially in older adults. It also decreased the bias of the estimated GFR. The FAS equation is applicable to adults and may be an alternative to measuring eGFR in China. .