Approximately 58 million people are living with chronic hepatitis C virus (HCV) infection worldwide, with an estimated 1.5 million new infections occurring annually [1]. Around 70% of people infected with HCV will develop chronic HCV infection, which can lead to liver cirrhosis and cancer if left untreated [1]. Early reliable detection of HCV is essential for management of patients with HCV infection and reducing the risk of HCV transmission by infected bodily fluids [2, 3].
Serological assays for antibodies to HCV (anti-HCV) can identify people with current, resolved or treated HCV infection, while nucleic acid testing (NAT) for HCV ribonucleic acid (RNA) or an HCV core antigen (HCV-Ag) assay can be used to diagnose acute HCV infection, when antibodies may be undetectable [4]. HCV-Ag assays have a lower diagnostic sensitivity for HCV and a slightly longer diagnostic window (2–3 days) compared with NAT testing; however, the clinical utility of HCV-Ag assays has been demonstrated previously [5, 6]. Furthermore, the European Association for the Study of the Liver recommends that an HCV-Ag assay can be used for the diagnosis of acute or chronic HCV infection instead of NAT [7].
Anti-HCV serological assays are generally used as first-line tests for the diagnosis of patients with suspected HCV infection and for screening purposes [8]. A major challenge in detecting HCV infection using anti-HCV assays is the long diagnostic window, during which a patient with HCV infection undergoes seroconversion and can test negative for anti-HCV, leading to a false-negative result if NAT or HCV-Ag testing is not performed in parallel [9]. This window can last 8 weeks after initial infection, or longer in patients who are severely immunocompromised (e.g., patients on hemodialysis) [9].
Fourth generation HCV antigen-antibody (Ag-Ab) combination assays could shorten the diagnostic window and take advantage of antibody detection in situations where HCV-Ag and HCV NAT might provide negative results in HCV-infected individuals or when HCV NAT is not available [10], [11], [12]. The Elecsys® HCV Duo immunoassay (Roche Diagnostics GmbH, Mannheim, Germany) is an electrochemiluminescence “ECLIA” immunoassay for the in vitro qualitative simultaneous detection of HCV-Ag and anti-HCV in human serum and plasma and is intended for use on cobas e immunoassay analyzers (Roche Diagnostics International Ltd, Rotkreuz, Switzerland). The Elecsys HCV Duo immunoassay is the first test to provide parallel, but separate, read-out of HCV-Ag and anti-HCV results compared with other combination assays that show a combined result only. Additionally, a final Elecsys HCV Duo result is calculated equal to the highest cut-off index value of the sub-results (HCV-Ag and anti-HCV). In conjunction with other laboratory tests and clinical information, the assay has potential as a first-line diagnostic and screening test for HCV infection in clinical laboratories and as a screening tool for blood products in blood donation centers. The sub-results are intended to aid the selection of the confirmatory testing algorithm for reactive samples. The Elecsys HCV Duo immunoassay is approved for clinical use in Conformitè Europëenne (CE)-marked countries.
This study evaluated the diagnostic accuracy of the Elecsys HCV Duo immunoassay in an international, multicenter study, and compared its performance to commercially available assays.
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