Is Anti-Hepatitis C Virus Antibody Level an Appropriate Marker to Preclude the Need for Supplemental Testing

In the present study, we aimed to determine whether signal-to-cutoff (S/Co) ratios of reactive anti-HCV samples could be used as a basis for avoiding the need for supplemental testing in our study population.

We analyzed 901 anti-HCV-positive sera from 8 institutions in China. The Ortho VITROS anti-HCV assay and Monolisa Plus anti-HCV version 2 were used as screening assays to detect anti-HCV antibodies. Recombinant immunoblot assay (RIBA) and quantitative tests for HCV RNA were performed to validate confirmed HCV infection status.

Receiver operating characteristic curve analyses demonstrated that 41.5% (114/275) of true-positive samples with S/Co ratios ≤3.0 would be missed and the negative predictive value was 63.9 and 87.06%, using real-time polymerase chain reaction (RT-PCR) and RIBA as supplemental testing, respectively. 29.8% (90/302) of those who tested positive by RIBA samples were missed when only RT-PCR was used as supplemental testing.

We determined that very low anti-HCV levels (S/Co ≤3.0), as determined by chemiluminescence immunoassay, was not an appropriate marker to preclude the need for supplemental testing in our study population. A screening strategy employing a secondary HCV antibody assay using different HCV antigens from the first assay as the supplemental testing method should be studied further. The immunoblot assay, as a supplemental testing method, is still necessary.