Diagnostic performance and clinical utility of an HCV antigen-antibody combination assay across diverse real-world cohorts

ABSTRACT The traditional two-step serological screening algorithm for hepatitis C virus (HCV) is frequently hindered by diagnostic delays, high molecular testing costs, and high false-positive rates due to non-specific serological interference. The Elecsys HCV Duo assay simultaneously detects HCV core antigen (Ag) and anti-HCV antibodies (Ab); however, comprehensive validation across highly heterogeneous clinical populations, particularly in highly vulnerable groups such as hemodialysis patients, remains limited. This study aimed to evaluate the real-world diagnostic and operational utility of the HCV Duo assay across diverse clinical cohorts. This multi-center study evaluated 1,844 patients stratified into hemodialysis ( n = 856), outpatient ( n = 477), inpatient ( n = 384), and health checkup ( n = 127) settings. Using HCV RNA as the reference standard, the dual-marker assay effectively eliminated 98.8% of low-reactivity (cutoff index [COI] 0.90–3.00) and 44.2% of moderate-reactivity (COI 3.01–10.00) conventional false positives. The Ag module achieved 66.51% overall sensitivity, 99.88% specificity, and a 98.58% positive predictive value. Notably, the assay maintained robust diagnostic reliability against uremia-induced interference in the hemodialysis cohort, where applying a Youden-optimized diagnostic threshold improved Ag sensitivity from 65.0% to 75.0%. Translating these performance metrics into a profile-driven triage strategy safely eliminated the need for routine RNA confirmatory testing in up to 33.3% of the simulated cohort, significantly reducing reliance on downstream molecular analysis. IMPORTANCE The HCV Duo assay offers simultaneous antigen and antibody detection; however, laboratories lack robust evidence regarding its operational utility across highly diverse patient populations. Consequently, screening protocols remain reliant on delayed and costly RNA confirmation, particularly for complex groups like hemodialysis patients, where uremic interference frequently confounds standard serological testing. This study fills this gap by demonstrating the assay’s robust diagnostic stability across four distinct clinical environments while specifically resolving the long-standing serological blind spot in the hemodialysis cohort. By providing evidence-based, cohort-specific insights and an actionable triage algorithm, this research enables laboratories to implement more efficient, tailored screening pathways. These advances significantly reduce the reliance on unnecessary molecular testing, accelerate clinical decision-making, and provide a pragmatic framework to support global HCV elimination mandates.