Improve The Mdrd Equation Validation And Gfr Evaluation Equation Applicability Of Patients With Chronic Kidney Disease Research In Our Country

[OBJECTIVE]To compare the diagnosic performance of the Chinese modified MDRD equation with that of the original simplified MDRD equation and evaluate the applicability of several GFR estimation equations on chronic kidney disease (CKD) patients in China.[METHODS]Reference GFR (rGFR) of176patients with CKD were detected by99mTc-DTPA plasma clearance rate two-sample method. Serum creatinine was detected with Picric acid method and enzymatic method respectively. Cystatin C was measured by particle-enhanced turbidimetric immunoassay (PETIA) and particle-enhanced nephelometric immunoassay (PENIA) respectively. Compared difference between eGFR and rGFR in different equations as follows, Cockcroft-Gault Equation (C&G/BSA), simplified MDRD equation, IDM-traceable MDRD equation, CKD epidemiology collaborative research (CKD-EPI) equation, two Chinese simplified MDRD equation (equation1,2) and several Cystatin C based eGFR equations.[RESULTS]The rGFR of176patients with CKD, measured by99mTc-DTPA plasma clearance rate two-sample method was54.74±43.97ml/min/1.73m2.(1) Analysis of correlation between rGFR and eGFR shows the ICC of both modified equations are higher than that of simplified MDRD equation, but the difference is not statistical significant (P>0.05). CKD-EPI has the highest ICC (P>0.05); Comparing with other equations in overall30%accuracy, some improvement was achieved by CKD-EPI (P>0.05), both modified MDRD equations showed improvements compared to simplified MDRD equation(P>0.05); X2test demonstrated that CKD-EPI equation performed best in correct staging ratio. In patients with stage1CKD, compared to simplified MDRD equation, modified equation1produced higher correct staging ratio(P<0.05); Bland-Altman analysis indicates modified equation1and2produced smaller deviation than simplified MDRD equation. CKD-EPI equation produced the eGFR with smallest deviation and highest accuracy.(2) The intraclass correlation coefficient (ICC) between eGFR of Cystatin C based equations and rGFR ranged from0.910to0.938.Compared with rGFR, the30%accuracy of all eight equations based on cystatin c were lower than60%. In patiens with stage1CKD, correct staging ratio of all the cystatin C based equations was between58%and100%.In patiens with stage2to4, all the cystatin c based equations performed poorly with correct staging ratio less than50%;In patients with rGFR≥60ml/min/1.73m2,the30%and50%accuracy of all eight equations based on cystatin C were better than the accuracy of the equations in patients with rGFR<60ml/min/1.73m2(P<0.05).[CONCLUSIONS](1)Compared with simplified MDRD equation, the diagnostic performance of modified equation1was improved.mainly in patients with rGFR≥60ml/min/1.73m2. Compared to the other equations, the improvements of of CKD-EPI equation, in bias, accuracy and correct CKD staging, is noticeable but not ideal.(2)None of the eight cystatin C based formulas were acceptable for estimating GFR in Chinese CKD patients. Further studies should be performed to develop more accurate cystatin C based eGFR equations.