Evaluation of Quantitative Hepatitis C Virus Core Antigen Testing as a Tool for Screening and Confirmation of HCV Infection.

Background: Hepatitis C is a common viral infection worldwide. Finding the most effective diagnostic methods with low cost is always needed for laboratory improvement. In this study, we evaluated the performance of a quantitative chemiluminescent hepatitis C virus core antigen (HCV cAg) test by comparing it with the HCV confirmatory antibody line immunoblot assay (HCV Ab-LIA) test as well as the HCV quantitate reverse transcription-polymerase chain reaction (qRT-PCR) test.

Methods: A total of 394 samples were enrolled in the retrospective study. Of these, 225 samples were tested using HCV Ab screening and confirmatory Ab-LIA along with chemiluminescent HCV core Ag testing, while 169 samples were tested using qRT-PCR for HCV RNA and chemiluminescent HCV core Ag testing.

Results: Out of these, 225 positive samples tested by HCV Ab screening test were analyzed using the confirmatory Ab LIA and HCV cAg assays, a total of 183 samples (81.3 %) were confirmed to be Ab-positive, and among those, 77 samples (42.1%) were also positive for HCV cAg. Thirty-eight samples (20.76%) were HCV Ab indeterminate, and all of them were HCV cAg negative. Four samples (1.8%) were HCV Ab LIA-negative and negative for HCV cAg. Moreover, 169 samples were measured for qRT-PCR HCV viral load and quantitative HCV cAg test. One hundred and three samples were positive for HCV RNA, while 66 were negative. Among the positives, 96/103 samples were HCV cAg positive and 7/103 samples were negative. Out of the negatives, 4/66 samples were HCV cAg positive but 62/66 samples were negative. The HCV cAg results were concordant with the qRT-PCR results in 158 samples (93.5%); however, 11 samples (6.5%) were found to be discrepant. The sensitivity, specificity, positive predictive value, and negative predictive value of the quantitative HCV cAg were found to be 93%, 94%, 96%, and 90%, respectively. The overall coefficient of correlation between the HCV RNA levels and HCV cAg data was determined to be r2 = 0.9.

Conclusions: The HCV cAg test showed a high correlation with the HCV RNA levels and may potentially be used as a more cost-effective alternative to the HCV RNA qRT-PCR test.