Accuracy with glomerular filtration rate estimation in chronic kidney disease using cystatin C combined with creatinine

Abstract

Objective To verify the adaptability of CKD-EPI equation developed based on cystatin C in America in 2008 among Chinese patients with chronic kidney disease (CKD).Methods Between December 2008 and April 2009, 68 non - dialysis CKD patients were recruited and calculated for their glomerular filtration rates(GFRs) by Cockcroft-Gault equation, simplified MDRD equation, modified MDRD equation and gates method with 99mTc-DTPA (cGFR, aGFR, mGFR, gGFR) and three CKD-EPI estimating equations developed based on cystatin C (CyslGFR, Cys2GFR, Cys3GFR).All the results above were then compared and analyzed with tGFR determined by double plasma sample method of GFR with 99mTc-DTPA.Results Pearson analysis demonstrated that seven estimated GFRs (cGFR, aGFR, mGFR, gGFR,cyslGFR, cys2GFR, cys3GFR) were significantly correlated with tGFR, with Cys3GFR showing the highest correlation coefficient (0.93) , followed by gGFR (0.91) , mGFR (0.89) , Cys2GFR (0.88) , CyslGFR (0.85), cGFR(0.85), and aGFR(0.83).Cys3GFR yielded results that were more accurate than did aGFR or CyslGFR.Bland-Altman analysis demonstrated that Cys3GFR had the best consistency with tGFR which did not exceed the predetermined limits.The outcome of linear regression showed that the modified MDRD equation had the least deviation and the highest precision.Conclusion In Chinese population, the third CKD-EPI equation (Cys3GFR) including cystatin, creatinine and demographic statistics has favorably greater accuracy, and best consistency and correlation with tGFR, as compared with the first CKD-EPI equation based on cystatin C alone, Cockcroft-Gault equation or simplified MDRD equation. Key words: Clomemlar filtration rate; Cystatin C; Creatinine; Chronic kidney disease; Accuracy