Diagnostic value of cystatin C and glomerular filtration rate formulae in Chinese nonelderly and elderly populations

Abstract

Serum cystatin C has been recognized as a surrogate marker for serum creatinine (SCr). However, whether cystatin C and cystatin C-based glomerular filtration rate (GFR) formulae offer any diagnostic value in nonelderly and elderly subjects has rarely been investigated. Reference GFR (rGFR) values were established using the 99mTc-DTPA renal dynamic imaging method. Nine GFR formulae were used to predict estimated GFR (eGFR). A total of 534 Chinese participants were enrolled. Cystatin C had a better diagnostic value than SCr. The superiority of cystatin C was more distinctly observed in the elderly. Combined cystatin C and SCr gave similar diagnostic values to cystatin C alone (p>0.05). Compared with single markers, GFR prediction formulae improved accuracy. Each formula had its own characteristics and applicability. Most formulae predicted with higher accuracy in the elderly than they did in the nonelderly. In chronic kidney disease (CKD) stage 1, the CKD-EPI formula had the least bias and the highest accuracy for the nonelderly, while the Hojs and Ma formulae performed best for the elderly. In the CKD stage 2-3, the Macisaac formula gave the most accurate eGFR. In the CKD stage 4-5, it was the CG formula that gave the closest estimate to the rGFR. Cystatin C could be superior to SCr, particularly in the elderly; however, cystatin C formulae and SCr formulae may possess their own applicability in different CKD stages and age groups. At present, it is not possible to say that cystatin C formulae are superior to SCr formulae.