Serum cystatin C is superior to serum creatinine as a marker of kidney function: A meta-analysis

Background: Serum cystatin C (Cys C) has been proposed as a simple, accurate, and rapid endogenous marker of glomerular filtration rate (GFR) in research and clinical practice. However, there are conflicting reports regarding the superiority of Cys C over serum creatinine (Cr), with a few studies suggesting no significant difference. Methods: We performed a meta-analysis of available data from various studies to compare the accuracy of Cys C and Cr in relation to a reference standard of GFR. A bibliographic search showed 46 articles until December 31, 2001. We also retrieved data from eight other studies presented and published in abstract form. Results: The overall correlation coefficient for the reciprocal of serum Cys C (r = 0.816; 95% confidence interval [Cl], 0.804 to 0.826) was superior to that of the reciprocal of serum Cr (r = 0.742; 95% Cl, 0.726 to 0.758; P < 0.001). Similarly, receiver operating characteristic (ROC)-plot area under the curve (AUC) values for 1/Cys C had greater identity with the reference test for GFR (mean ROC-plot AUC for Cys C, 0.926; 95% Cl, 0.892 to 0.960) than ROC-plot AUC values for 1/Cr (mean ROC-plot AUC for serum Cr, 0.837; 95% Cl, 0.796 to 0.878; P < 0.001). Immunonephelometric methods of Cys C assay produced significantly greater correlations than other assay methods (r = 0.846 versus r = 0.784; P < 0.001). Conclusion: In this meta-analysis using currently available data, serum Cys C is clearly superior to serum Cr as a marker of GFR measured by correlation or mean ROC-plot AUC.