Abstract:

Objective To know the status of cystatin C （Cys C） determination in Shanghai,through analyzing 4 external quality assessment and 1 flight-inspection-survey from 2014 to 2015,and to provide a reference for improving Cys C external quality assessment and the selection of quality control materials. Methods The quality control materials of external quality assessment were serum matrix quality control materials from Randox Company. The flight-inspection-survey specimens were serum samples prepared from the Clinical Chemistry Laboratory from Shanghai Center for Clinical Laboratory and from Shanghai Beijia Company. The concentration of quality control materials was 0.7-9.0 mg/L. The median of the results of external quality assessment was as target value. The flight-inspection-survey results were analyzed by primary reference material transfer target assignment value and median value. The results were classified into domestic reagent group,imported reagent group and other reagent group and analyzed statistically. The standard of qualified judgment was ±25%,and the group coefficients of variation （CV） and total CV were calculated,and group pass rates and total pass rate were also calculated. Results The total CV and group CV of 2 external quality assessment in 2014 and flight-inspection-survey in 2015 were 15%-20%,but the CV of high-concentration samples（6.3 and 8.9 mg/L） of the 2nd external quality assessment in 2014 were >25%. There was no difference for CV between domestic and imported reagent groups. The pass rate of imported reagent group（>90%） was higher than that of domestic reagent group,and the results of Sysmex was higher than those of other imported reagents. In domestic reagent group,the pass rate was the lowest when the concentration of samples was about 6.0 mg/L,which was <80%. The external quality assessment samples in 2015 had only 2 concentrations at about 0.7 mg/L and 3.4 mg/L. The total and group CV and the pass rates of external quality assessment in 2015 were better than those in 2014 and those in flight-inspection-survey in 2015,the CV were <10%,and the pass rates were >95%. However,in the 1st external quality assessment,the results using imported reagent Sekisuithe in low-concentration samples of 0.7 mg/L appeared wholly lower than lower limit,resulting in the imported reagent group at low-concentration with only 68% of pass rate. The flight-inspection-survey results were analyzed using the primary reference material transfer target assignment value and median value,and there were no differences in the results of the other 4 samples except for the low-concentration sample（0.7 mg/L）. Conclusions Though the total and group CV and the pass rates of external quality assessment in 2015 are better than those in 2014,the results of flight-inspection-survey in 2015 are consistent with the results of external quality assessment in 2014,so the status of Cys C determination may not be reflected by external quality assessment in 2015. The concentration should be in the range of 0.7-5.0 mg/L.

Key words: Cystatin C, External quality assessment, Flight-inspection-survey, Shanghai