Abstract:

Objective To set the gray zones of 4 commonly-used domestic anti-hepatitis C virus（HCV）antibody detection kits in clinical laboratories of Shanghai. Methods A total of 656 cases diagnosed as anti-HCV antibody positive initially were collected,and 4 domestic anti-HCV antibody detection kits,Rongsheng,Xinbo,Kehua and Kemei,were used for review. The review rates of different initial detection signal-to-cut off（S/CO）ratio were calculated,respectively. A total of 338 weakly-positive samples with inconsistent initial and review results were chosen. Recombinant immunoblot assay（RIBA）was used for validation test,and for samples showing uncertain,fluorescence quantitation polymerase chain reaction（PCR）was used for the detection of HCV RNA. The results of RIBA and HCV RNA were as gold standard,and receiver operating characteristic （ROC） curve was used to discuss optimal S/CO ratio. With 95% true positive and 95% true negative S/CO ratios,the negative and positive gray zones for 4 domestic anti-HCV antibody detection kits were identified. Results The 4 domestic anti-HCV antibody detection kits′ negative review rates were > 90%,S/CO ratios were >12.01,and their positive review rates were > 95%. The optimal S/CO ratios for Rongsheng,Xinbo,Kehua and Kemei were 1.31,2.48,3.22 and 4.32,respectively. With 95% true positive rates and 95% true negative rates for determining 4 domestic anti-HCV antibody detection kits′positive and negative cut-off values,the gray zones for optimal S/CO ratios were 0.6-1.3, 0.7-2.5,0.7-4.0 and 0.7-4.3,respectively. Conclusions The 4 commonly-used domestic anti-HCV antibody detection kits′optimal S/CO ratios are confirmed. It provides 4 kinds of gray zones for anti-HCV antibody detection kits in clinic.

Key words: Anti-hepatitis C virus antibody, Cut-off value, Gray zone