Evaluation of Quantitative Real‐Time PCR as a Hepatitis C Virus Supplementary Test After RIBA Discontinuation

Abstract

Laboratory testing plays a major role in hepatitis C virus (HCV) diagnosis and patient follow-up. The high false positive rates of HCV screening tests require confirmation through a supplementary test. According to the 2003 CDC guidelines, recombinant immunoblot assay (RIBA) is indispensible to confirm positive screening results and differentiate biologic false positivity from true HCV exposure. However, RIBA has been permanently discontinued since 2011. In the 2013 update of its guidelines, CDC called for further studies on HCV laboratory testing without RIBA. In this study, we analyzed the applicability of quantitative real-time PCR (qPCR) as a supplementary HCV diagnostic test. By comparing our HCV testing performances before and after RIBA discontinuation, we found that omitting RIBA has no significant effect on the accurate and efficient identification of HCV infection, provided that HCV antibody signal-to-cutoff ratio is considered. Furthermore, we proposed a new HCV testing algorithm that incorporates semiquantitative assessment of HCV antibody positivity and HCV viral load measurement by qPCR. By following the algorithm, we were able to address confirmation of positive HCV screening results and to provide useful information generally required by clinicians, including the needs of further laboratory testing or clinical follow-up, as well as HCV viral titers.

The Role of the Signal-to-Cutoff Ratio in Automated Anti-HCV Chemiluminescent Immunoassays by Referring to the Nucleic Acid Amplification Test and the Recombinant Immunoblot Assay

“…One patient showed a marked decline in the S/CO ratio to <2 within only two years. A high S/CO ratio with a negative NAAT may be regarded as a resolved infection [ 30 ]. However, in the patients with spontaneous recovery after infection without subjective symptoms (15–45%) [ 4 ], it is difficult to distinguish false-positive results from low S/CO ratio solely on the basis of their medical history, as they overlap with the false-positive results at low S/CO ratios.…”

“…Some biochemical tests (e.g., alanine aminotransferase, albumin, cholesterol) are helpful in diagnosing HCV infection but are only distinctive in acute HCV infection (data not shown). In some studies, however, there was no difficulty in diagnosing HCV infection despite the permanent discontinuation of RIBA [ 30 ]. Our study demonstrated that positive results would not seem to be conclusive of HCV infection without supplemental RIBA testing.…”

Determination of anti-HCV signal to cut-off value in patients with hepatitis C virus infection and the variety of antibody responses

“…In another study, it is stated that RIBA is needed for patients with EIA reactive, NAAT negative results, thus a better evaluation could be made by following these patients who recovered from HCV infection. Nevertheless, it has been stated that neglecting RIBA has a minimal effect on HCV diagnosis, provided that the anti-HCV S / Co ratio is included in the diagnostic algorithm [37]. Despite the decision of CDC to remove RIBA from the diagnostic algorithm for HCV, some authors reported that their results indicate the RIBA should continue to be used [10].…”