Accuracy of Glomerular Filtration Rate Equations for Chronic Kidney Disease Patients at the G3a Stage: a Single-center Cross-sectional Study

Background: Kidney disease improving global outcomes provided a new classification for chronic kidney disease (CKD) by subdividing the G3 stage into G3a and G3b stages based on glomerular filtration rate (GFR) in 2012. Currently, a few methods are used to evaluate GFR, including measured GFR (mGFR) and estimated GFR (eGFR). One of the mGFR was Tc-DTPA scintigraphy method and eGFR using GFR equations were used clinically. Equations were modification of diet in renal disease (MDRD), chronic kidney disease epidemiology collaboration (CKD-EPI), and Chinese adapted MDRD (C-MDRD). This study assessed the accuracy of three different equations for estimated glomerular filtration rate (eGFR) with mGFR using DTPA scintigraphy method as the standard in a population of Chinese chronic kidney disease patients at the G3a stage.

Results: One hundred and twenty-two patients (age 52.0 ± 15.6 years, 69 were male) were determined as CKD stage 3 based on mGFR. Patients were divided into G3a (47 patients) and G3b (75 patients) subgroups. Bias between eGFR for CKD-EPI and reference mGFR was 0.92 mL/min and 95% limits of agreement was -38.82 to 40.67 mL/min. Bias between eGFR for C-MDRD and mGFR was 3.76 and 95% limits of agreement was -39.32 to 46.85 mL/min. Bias between eGFR for MDRD and mGFR was 3.53 and 95% limits of agreement was -43.35 to 50.4 mL/min. The CKD-EPI equation showed better diagnostic value with a greater area under the receiver operating characteristic curve (AUC: 0.763). AUC for MDRD and C-MDRD were 0.75 and 0.757, respectively.

Conclusions: There were no obvious advantages in accuracy, sensitivity, and specificity for the diagnosis of patients at the G3a stage using the CKD-EPI equation.