Evaluation of glomerular filtration rate by different equations in Chinese elderly with chronic kidney disease.

Purpose: Performance of equations in elderly with chronic kidney disease (CKD) was debated. We aimed to access the performances of estimating equations for glomerular filtration rate in Chinese elderly population with chronic kidney disease.

Methods: Participants [N = 218, median age, 82 (range 75-96)] with CKD underwent renal dynamic imaging using technetium-99m diethylene-triamine-penta-acetic acid (99mTc-DTPA). The performances of glomerular filtration rate equations including the Cockcroft-Gault equation, the MDRD (Modification of Diet in Renal Disease) equation for Chinese, 3 CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equations, and 2 BIS (Berlin Initiative Study) equations were compared.

Results: Median mGFR was 47.62 (3.00-135.00) ml/min/1.73 m. Smaller biases were shown in BIS-2 equation and CKD-EPI-Cr equation (0.63 ml/min/1.73 m and -1.22 ml/min/1.73 m). Interquartile range of the differences was least with BIS-2 equation and CKD-EPI-Cr-Cys equation (4.36 ml/min/1.73 m and 9.17 ml/min/1.73 m). For accuracy (percentage of eGFR within 30 % of the mGFR, P30), performance of BIS-2, CKD-EPI-Cr-Cys, and BIS-1 equation was superior (94.50, 89.91, and 88.53 %, respectively). In terms of accuracy (root-mean-square error, RMSE), BIS-2 equation, CKD-EPI-Cr-Cys equation, and BIS-1 equation also performed better (7.21 ml/min/1.73 m, 8.87 ml/min/1.73 m and 9.82 ml/min/1.73 m). GFR category misclassification rates were smaller in BIS-2 equation, CKD-EPI-Cr-Cys equation and BIS-1 equation (16.51, 20.64, and 25.69 %, respectively).

Conclusion: Compared with other equations, the BIS-2 equation performed better in the estimation of glomerular filtration rate for Chinese elderly with CKD aged 75 or above.