Using Mathematical Algorithms to Modify Glomerular Filtration Rate Estimation Equations

Abstract

BackgroundThe equations provide a rapid and low-cost method of evaluating glomerular filtration rate (GFR). Previous studies indicated that the Modification of Diet in Renal Disease (MDRD), Chronic Kidney Disease-Epidemiology (CKD-EPI) and MacIsaac equations need further modification for application in Chinese population. Thus, this study was designed to modify the three equations, and compare the diagnostic accuracy of the equations modified before and after.MethodologyWith the use of 99 mTc-DTPA renal dynamic imaging as the reference GFR (rGFR), the MDRD, CKD-EPI and MacIsaac equations were modified by two mathematical algorithms: the hill-climbing and the simulated-annealing algorithms.ResultsA total of 703 Chinese subjects were recruited, with the average rGFR 77.14±25.93 ml/min. The entire modification process was based on a random sample of 80% of subjects in each GFR level as a training sample set, the rest of 20% of subjects as a validation sample set. After modification, the three equations performed significant improvement in slop, intercept, correlated coefficient, root mean square error (RMSE), total deviation index (TDI), and the proportion of estimated GFR (eGFR) within 10% and 30% deviation of rGFR (P10 and P30). Of the three modified equations, the modified CKD-EPI equation showed the best accuracy.ConclusionsMathematical algorithms could be a considerable tool to modify the GFR equations. Accuracy of all the three modified equations was significantly improved in which the modified CKD-EPI equation could be the optimal one.

A New Modified CKD-EPI Equation for Chinese Patients with Type 2 Diabetes

“…In the validation data set, the new modified equation achieved less bias, higher precision and greater accuracy compared with all three original equations. These results were consistent with the previous findings [15] , [21] – [26] that modification of the original equation in a local cohort which was quiet different to the original one may improve the performance of GFR estimation in the same population. And our results will help clinicians to make suitable clinical decision for diabetic patients and avoid unnecessary examination and treatment.…”

“…GFR was measured by the 99mTc-diethylene triamine pentaacetic acid ( 99 m Tc-DTPA) renal dynamic imaging method [14] – [15] , as described previously [16] . The minimum sample size was determined to be as 36 based in the findings in a previous study [17] .…”

Estimating glomerular filtration rate by serum creatinine or/and cystatin C equations: An analysis of multi‐centre Chinese subjects

“…Chinese investigators have proposed a series of GFR estimation equations based on serum creatinine or/and cystatin C in recent years . Yet, only limited data exist outside the development cohort regarding their application in Chinese individuals.…”

“…22 Chinese investigators have proposed a series of GFR estimation equations based on serum creatinine or/and cystatin C in recent years. [4][5][6][7] Yet, only limited data exist outside the development cohort regarding their application in Chinese individuals. In our previous study, CKD-EPIscr-cys achieved ideal performance in overall population while Mascr and Mascr-cys equations appeared more biased and less accurate.…”

“…Analogous to different epidemiological studies in other countries, the CKD prevalence was reported to be 10.8% in China, equivalent to 119.5 million CKD patients. 1 To find an accurate, convenient, and reproducible GFR-estimating method, a series of GFR-estimation equations utilizing cystatin C instead of, or in addition to, creatinine have been proposed by the CKD-EPI collaboration (CKD-EPIscr, 2 CKD-EPIcys 3 and CKD-EPIscr-cys 3 equations) and Chinese investigators (Mascr, 4 Peiscr, 5 Macys, 6 Fengcys, 7 Mascr-cys 6 and Fengscr-cys 7 equations). These equations, however, are not fully validated in the Chinese population outside of their original development population, and the question exists whether GFR estimation is improved using cystatin C based equations.…”