Value Of Core Antigen Assay In The Diagnosis Of HCV Infection

Objective:TostudythecorrelationbetweenhepatitisC virus(HCV)core antigen(core Ag,cAg)and HCV nucleic acid(HCV-RNA)quantification,and to explore whether cAg detection by Enzyme-linked immunosorbent assay(ELISA)can be used as a surrogate marker for detection of HCV-RNA for the diagnosis of hepatitis C.Methods:We collected data of patients with hepatitis C antibody(anti-HCV)positive who were admitted into our hospital between2015.01.01-2018.05.31,the data includes age,sex,anti-HCV,cAg,HCV-RNA,and genotype assay,etc.To analyze the correlation between cAg and HCV-RNA and whether there is any difference in cAg positive rate between different genotypes and different HCV-RNA levels,and to clarify the role of cAg in the diagnosis of hepatitis C.Results:A total of 1217 patients with anti-HCV antibody positive were included with 909 cases of HCV-RNA positive and 498cAg-positive.496 cases are both positive for cAg and HCV-RNA.There were 768 cases genotyped successfully,which were 102,54,317,2,241cases of type 1,type 2,type 3,type 4 and type 6 respectively,and 52 cases were not classified.The specificity(SP)of cAg was 99.35%with the HCV-RNA quantitative assay as the gold standard,the positive predictive value(PPV)was 99.60%,the sensitivity(SE)was 54.57%,and the negative predictive value(NPV)was 42.56%.The correlation coefficient between cAg and HCV RNA was rs=0.477(P=0.000).With the increase in the level of HCV-RNA,the positive rate of cAg detection increased;at low levels,the positive rate was extremely low(cAg positive rate<30%,when HCV-RNA was<1x10~5).The positive rate of cAg in various genotypes was different,and the rates were 72.55%,59.26%and 38.49%,65.98%,respectively for the genotype 1,type 2,type 3 and type 6(P=0.000).Conclusion:The detection of cAg by ELISA is poorly correlated with HCV-RNA level.When the virus level is low,the positive rate of cAg detection becomes lower.Its role in the diagnosis of hepatitis C is very limited,therefore cannot be used as a substitute marker for HCV-RNA detection in the diagnosis of HCV infection.