Applicable Research On The EGFR Equations Based On Creatinine Or/and Cystatin C In Chinese CKD Population

Objective To confirm the feasibility of implementing eGFR formulas in China, the impact of different detection methods and systems of serum creatinine (Cr) and cystatin C (Cys C) on the calculating results of estimated GFR (eGFR) was assessed; and further applicability of these Cr and Cys C-based GFR predictive equations in Chinese CKD population was tested to choose the more applicable eGFR predictive equations and better indicator; at last to develop the eGFR equations based on Chinese CKD population.Methods Performance of six kinds of creatinine reagents with enzymatic method and three kinds of cystatin C reagents with particle-enhanced turbidimetric immunoassay (PETIA) method commercially available used on the automatic biochemistry analyzer were assessed to grasp the consistency status quo of the performance and test results of domestic Cr and Cys C reagents. Serum creatinine was detected using five different systems of enzymatic or picric acid creatinine reagent, and Cystatin C was detected using three different systems of PETIA and PENIA methods. These detecting results were put into six Cr-based eGFR equations and nine Cys C-based eGFR equations to calculate and compare the eGFR to screen the optimum Cr-based eGFR equations and Cys C-based eGFR equation for China CKD population. The applicability of preferential equations and equations based on combined Cr and Cys C in Chinese CKD patients were also compared. Clearance of dual plasma sampling99mTc-DTPA was used as the reference of glomerular filtration rate (rGFR), according to the data of multi-center CKD patient, race coefficient was added into the preferential CKD-EPI equations to optimize these equations, and PUMCH equation was also developed based on the multivariate linear regression the method.Results The four kinds of domestic and two imported enzymatic Cr reagents and three kinds of domestic PETIA method Cys C reagents assessed were all with high precision, sensitivity and linear range. No significant differences were found in performance among domestic and imported Cr reagents. Four kinds of Cr reagents among six reagents results gave satisfactory consistency, and the other two reagents exist positive deviation and negative deviation. Significant deviations were found among three kinds of the PETIA method Cys C reagents with Dade Behring PENIA reagents results, and there are also significant differences among the three kinds of reagents with PETIA methods. Significant differences were found for the same eGFR equation using different Cr or different Cys C detection method results. eGFR results calculated with Cr-GFR equation by using enzymatic Cr method were superior to those by using aspect picric acid method in correlation, degree of deviation and accuracy. The performance of Cys C-GFR equations using the same method as that of the equation developed to measure Cys C is better than using other different methods. CKD-EPICr equation and CKD-EPICysC (Age, gender, race correction) equation were better than other corresponding equations based on Cr or Cys C, respectively. CKD-EPICr/Cysc equation and CKD-EPICr/CysC(2012) equation are superior to the CKD-EPICr equation and CKD-EPICysC(Age, gender, race correction) equation in deviation, precision, relevance, accuracy, staging consistency, and so on. In this study three modified equations were developed by adding racial coefficients to CKD-EPI equation, and four PUMCH equations were developed by multiple linear regression. Performance of the modified equations of c-CKD-EPICr and c-CKD-EPICr/CysC(2012)were verified to improve compared to their original equations, while the performance of four newly developed PUMCH equations are not satisfactory.Conclusion Attention should be paid to the inconsistency of the Cys C results and Cr results when assessing eGFR by predictive equations. Promotion of the enzymatic Cr method favored to accelerate the consistency process of domestic Cr detection and promote the eGFR formulas. Promote the use of enzymatic creatinine conducive to harmonization of creatinine detection process and is conducive to promote the use of eGFR formulas. Cr-GFR equations and Cys C-GFR equation in our study were not the ideal equations to assessment GFR in our CKD population. CKD-EPI equation also requires further optimization. In this study, the new equation corresponding to the CKD-EPI equation compared to no significant advantage. There may also be other factors affect equation fitting. Tested Cr-GFR equations and Cys C-GFR equations were not ideal to evaluate GFR for Chinese CKD population, and CKD-EPI equation based on combined Cr and Cys C still requires further optimization. No much remarkable advantage has been found in our new developed PUMCH equation compared to the CKD-EPI Cr and Cys C combine-based equation, other factors affecting the fitting of equations may also exist and need further work to gain clear ideas.