Comparison of the applicability of seven calculation equations of glomerular filtration rate among elderly people in China

Abstract Background The evaluation of kidney injury severity is a crucial aspect of medical practice. At present, glomerular filtration rate (GFR) serves as the primary indicator for this assessment. Estimated GFR (eGFR) remains the most frequently utilized parameter in clinical settings. Numerous equations have been formulated based on serum creatinine (Scr) or serum cystatin C (Cysc) levels. However, there is a lack of consensus regarding the efficacy of these equations in assessing eGFR, particularly for elderly individuals in China. This study aimed to evaluate the applicability of the MDRD, MDRDc, CKD-EPI series, BIS1, and FAS equations within the Chinese elderly population. Methods A cohort of 298 elderly patients with measured GFR (mGFR) determined by the dual plasma sample clearance method using 99m-Technetium-diethylenetriamine-pentaacetic acid ( 99m Tc-DTPA) renal dynamic imaging was enrolled. The patients were categorized into three subgroups based on their mGFR levels. The eGFR performance was examined, taking into account bias, interquartile range (IQR), accuracy P30, and root-mean-square error (RMSE). Bland-Altman plots were employed to verify the validity of eGFR. Results The 298 participants had a median age of 71 years, with 167 (56.0%) being male. In reference to mGFR (48.77 ml/min/1.73 m 2 ), the CKD-EPI-Scr, CKD-EPI-Cysc, CKD-EPI-Scr-Cysc, MDRD, MDRDc, FAS, and BIS1 equations estimated GFR at 50.38, 49.08, 45.28, 51.65, 54.00, 38.73, and 48.80 ml/min/1.73 m 2 , respectively. Overall, no significant differences in bias were observed among the seven equations ( P > 0.05). In terms of IQR, P30, and RMSE, the BIS1 equation demonstrated superior accuracy compared to the other equations (14.61, 72.1%, and 13.53, respectively). When mGFR < 30ml/min/1.73m 2 , all equations underestimated the true GFR, with the highest accuracy reaching only 59%. Bland-Altman plots indicated that the BIS1 equation exhibited the highest accuracy, featuring a 95% confidence interval (CI) width of 52.37 when compared to the other equations. Conclusions This study suggested that the BIS1 equation stands out as the most applicable for estimating GFR in Chinese elderly patients with normal renal function or only moderate decline.