Improving Linkage to the HCV Care Cascade in Nonspecialist Settings: Evaluation of the Performance and Triage Utility of the Elecsys HCV Duo Assay in Japan

Background In Japan, the hepatitis C virus (HCV) care cascade is constrained at the transition from anti‐HCV antibody screening to confirmatory HCV ribonucleic acid (HCV RNA) testing in nonspecialist departments. As HCV prevalence declines and the population ages, the two‐step antibody‐to‐RNA algorithm becomes less efficient and vulnerable to loss to follow‐up. We evaluated whether the Elecsys HCV Duo assay could function as a triage test to strengthen linkage to care. Methods We conducted a two‐part study in Kumamoto Prefecture, Japan. First, a survey of 19 specialized institutions assessed hepatitis virus testing practices and downstream evaluation in nonspecialist departments. Second, 479 serum samples from patients undergoing HCV RNA quantification at four hospitals were prospectively evaluated using the Elecsys HCV Duo assay, with detection rates stratified by viral load. Results Nonspecialist departments accounted for 86.6% of in‐hospital anti‐HCV testing; however, among 1416 anti‐HCV–positive individuals identified outside gastroenterology departments, only 22.7% underwent confirmatory HCV RNA testing. In the prospective evaluation of 479 samples, HCVcAg sensitivity and specificity versus HCV RNA were 62.8% and 99.8%, respectively. Detection rates increased with viral load, from 0% at ≤ 4.0 log 10 IU/mL to 16.7% at 4.1–5.5 log 10 IU/mL and 86.2% at ≥ 5.6 log 10 IU/mL. Conclusion A vulnerability in the HCV care cascade lies at the transition from screening to confirmatory evaluation in nonspecialist settings. When implemented as a triage test within referral pathways, the Elecsys HCV Duo assay may improve linkage to specialist care while reserving HCV RNA testing for downstream confirmation.