Reflex threshold of signal-to-cut-off ratios of the Elecsys anti-HCV II assay for hepatitis C virus infection

Abstract

Introduction: Fast screening tests for hepatitis C virus (HCV) antibody often give false-positive results. Signal-to-cut-off (S/Co) ratios were suggested to be used as reflex confirmation of anti-HCV. The Elecsys Anti-HCV II assay is an effective test for the detection of hepatitis C, but no S/Co cutoff has been reported. The aim of this study was to determine the S/Co ratio threshold of anti-HCV test using Elecsys Anti-HCV II screening and supplemental recombinant immunoblot assay (RIBA) test results as the gold standard. Methodology: A total of 36,341 serum samples were tested for HCV antibody using the Elecsys Anti-HCV II assay and 276 positive samples were then tested with supplemental RIBA (Mikrogen recomLine HCV IgG strip immunoassay). Receiver operation curve (ROC) analysis was used to determine the cutoff, sensitivity, and specificity of the optimal S/Co ratio. Results: The Elecsys Anti-HCV II assay was positive (S/Co ratio ≥ 1) in 288 of the 36,341 samples (0.79%). RIBA testing on 276 of these 288 positive samples showed that all but one of 44 samples with an S/Co ratio of ≥ 1 and < 10 were negative, whereas the vast majority of samples (223/232, 96.1%) with an S/Co ratio ≥ 10 were positive. ROC analysis revealed that an optimal S/Co ratio cut-off value was 12.27. Conclusions: An S/Co ratio of 12.27 obtained with the Elecsys Anti-HCV II assay could be used as reflex confirmation of anti-HCV tests.

Performance evaluation of the mindray anti‐HCV assay for the detection of hepatitis C virus infection

“…CDC guidelines have recommended that the anti‐HCV threshold S/CO ratio can be used to reduce the necessity for supplemental testing and may provide additional insight into a subject's true anti‐HCV antibody status . Several previous studies have reported the threshold S/CO ratio, which predicts positive results in ≥ 95% of supplemental tests for a variety of anti‐HCV assays . Among the 181 samples with anti‐HCV CLIA‐positive results according to at least one assay, the percentages of samples with an S/CO ratio between 1.0 and 10.0 according to the Mindray anti‐HCV, Architect anti‐HCV and Elecsys anti‐HCV II assays were 14.9% (27/181), 60.7% (110/181), and 1.1% (2/181), respectively.…”

“…RIBA is labor‐intensive and time‐consuming and is no longer recommended as a supplemental test for anti‐HCV confirmation in the 2013 CDC guidelines, and only NAT is required . RIBA is still commonly used due to its high specificity in other countries, including China . In the present study, we used RIBA to analyze 181 samples with at least one anti‐HCV CLIA‐reactive result.…”

“…17 Several previous studies have reported the threshold S/CO ratio, which predicts positive results in ≥ 95% of supplemental tests for a variety of anti-HCV assays. 6,8,9,18 Among the 181 samples with anti-HCV CLIA-positive results according to at least one assay, the percentages of samples with an S/CO ratio In summary, the Mindray anti-HCV assay shows a high diagnostic performance, particularly in terms of high sensitivity, excellent specificity, and NPV, in the screening of routine clinical samples. However, our data suggest that each anti-HCV assay has limitations, including the potential for false-positive and false-negative results.…”

“…8 RIBA is still commonly used due to its high specificity in other countries, including China. 9 In the present study, we used RIBA to analyze 181 samples with at least one anti-HCV CLIA-reactive result. Among these samples, 47.5% (86/181), 12.2%…”

Hepatitis B and C prevalence and risk factors among young men presenting to the Brazilian Army

“…[25,26] Recent studies have shown that a Elecsys Anti-HCV II S/CO ratio within 12.27 to 19.0 is predictive of a true positive result in ≥95% of the cases. [27,28]…”