Objective:To analyze and compare the practical value of serum cystatin C(Scys C)and serum creatinine(SCr)in the assessment of kidney function in older adults.Methods:A retrospective, cross-sectional study was performed in 2 450 participants who were divided into a non-elderly group(<65 years)and an elderly group(≥65 years).Glomerular filtration rate(GFR), Scys C and SCr were measured by 99mTc-DTPA clearance, particle-enhanced immunoturbidimetry and an oxidase method, respectively.The χ2 test was used to compare increases in percentage of Scys C and SCr at the same GFR level.The screening value of Scys C and SCr for GFR<60 ml·min -1·1.73m -2was evaluated by the area under curve(AUC)of the receiver operating characteristic(ROC)curve.Values of 95% reference ranges were established for Scys C and SCr at different GFR levels. Results:The proportions of the general population with increased Scys C were 82.74%(556/672)and 94.74%(90/95), respectively, for GFR levels between 30~59 ml·min -1·1.73m -2and <30 ml·min -1·1.73m -2, while only 38.24%(257/672)and 75.79%(72/95)had elevated SCr levels( χ2=278.328, 13.571, both P<0.001).For the above GFR intervals, the proportions of older adults with increased Scys C were 84.81%(240/283)and 100.00%(43/43)respectively, and the proportions for non-elderly adults with increased Scys C were 81.23%(316/389)and 90.38%(47/52)( χ2=1.463, 4.364, P=0.226, 0.037), respectively.The screening value of Scys C for GFR<60 ml·min -1·1.73m -2was slightly better than SCr in terms of sensitivity, specificity and the Youden index.However, the sensitivity and specificity of Scys C in older adults were 76.4% and 75.7%, respectively, both lower than 78.7% and 84.0% in non-older adults.The variability of Scys C increased progressively with age.The reference range for Scys C was higher in older adults than in non-older adults at the same GFR level. Conclusions:When screening for GFR<60 ml·min -1·1.73m -2, the sensitivity and specificity of Scys C are slightly better than those of SCr, but are lower in older adults than in non-older adults.Scys C levels are higher and more variable in older adults.Using Scys C to assess GFR may lead to over-diagnosis of chronic kidney disease in older adults.

Humans ; Infant, Newborn ; Intensive Care Units, Neonatal ; Logistic Models ; Phenotype ; Risk Factors