Variability of glomerular filtration rate estimation equations in elderly Chinese patients with chronic kidney disease

Xun Liu,^1,2,* Mu-hua Cheng,^3,* Cheng-gang Shi,¹ Cheng Wang,¹ Cai-lian Cheng,¹ Jin-xia Chen,¹ Hua Tang,¹ Zhu-jiang Chen,¹ Zeng-chun Ye,¹ Tan-qi Lou<sup>1

1</sup>Division of Nephrology, Department of Internal Medicine, The Third Affiliated Hospital of Sun Yet-sun University, Guangzhou, China; ²College of Biology Engineering, South China University of Technology, Guangzhou, China; ³Department of Nuclear Medicine, The Third Affiliated Hospital of Sun Yet-sun University, Guangzhou, China

^*These authors contributed equally to this paper

Background: Chronic kidney disease (CKD) is recognized worldwide as a public health problem, and its prevalence increases as the population ages. However, the applicability of formulas for estimating the glomerular filtration rate (GFR) based on serum creatinine (SC) levels in elderly Chinese patients with CKD is limited.
Materials and methods: Based on values obtained with the technetium-99m diethylenetriaminepentaacetic acid (^99mTc-DTPA) renal dynamic imaging method, 319 elderly Chinese patients with CKD were enrolled in this study. Serum creatinine was determined by the enzymatic method. The GFR was estimated using the Cockroft–Gault (CG) equation, the Modification of Diet in Renal Disease (MDRD) equations, the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation, the Jelliffe-1973 equation, and the Hull equation.
Results: The median of difference ranged from −0.3–4.3 mL/min/1.73 m². The interquartile range (IQR) of differences ranged from 13.9–17.6 mL/min/1.73 m². Accuracy with a deviation less than 15% ranged from 27.6%–32.9%. Accuracy with a deviation less than 30% ranged from 53.6%–57.7%. Accuracy with a deviation less than 50% ranged from 74.9%–81.5%. None of the equations had accuracy up to the 70% level with a deviation less than 30% from the standard glomerular filtration rate (sGFR). Bland–Altman analysis demonstrated that the mean difference ranged from −3.0–2.4 mL/min/1.73 m². However, the agreement limits of all the equations, except the CG equation, exceeded the prior acceptable tolerances defined as 60 mL/min/1.73 m². When the overall performance and accuracy were compared in different stages of CKD, GFR estimated using the CG equation showed promising results.
Conclusions: Our study indicated that none of these equations were suitable for estimating GFR in the elderly Chinese population investigated. At present, based on overall performance, as well as performance in different CKD stages, the CG equation may be the most accurate for estimating GFR in elderly Chinese patients with CKD.

Keywords: elderly, equation, glomerular filtration rate, serum creatinine, Chinese