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

  • Jie Pan Nanfang Hospital of Southern Medical University, Guangzhou, Guangdong, China
  • Xin Li Nanfang Hospital of Southern Medical University, Guangzhou, Guangdong, China
  • Guowei He The Third Affiliated Hospital, Sun Yat-Sen University, Guangzhou, Guangdong, China
  • Shuai Yuan Nanfang Hospital of Southern Medical University, Guangzhou, Guangdong, China
  • Pingfeng Feng Nanfang Hospital of Southern Medical University, Guangzhou, Guangdong, China
  • Xiuming Zhang Zhongshan Hospital Affiliated to Sun Yat-Sen University, Zhongshan, Guangdong, China
  • Yurong Qiu Nanfang Hospital of Southern Medical University, Guangzhou, Guangdong, China
Keywords: hepatitis C, anti-HCV RIBA, Elecsys hepatitis C virus antibody assay, S/Co ratio

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.

Published
2016-09-30
How to Cite
1.
Pan J, Li X, He G, Yuan S, Feng P, Zhang X, Qiu Y (2016) Reflex threshold of signal-to-cut-off ratios of the Elecsys anti-HCV II assay for hepatitis C virus infection. J Infect Dev Ctries 10:1031-1034. doi: 10.3855/jidc.7301
Section
Brief Original Articles