Keisuke AMANO, Tomoya SANO, Tatsuya IDE, Dan NAKANO, Shigemune BEKKI, Teruko ARINAGA-HINO, Takumi KAWAGUCHI
Hepatology Forum - 2026;7(2):118-124
Background and Aim: The World Health Organization has a goal to eliminate the hepatitis C virus (HCV) by 2030. To achieve this, effective screening for HCV is essential. We evaluated the utility of the ELECSYS(R) HCV Duo immunoassay (Duo assay) for HCV screening. Materials and Methods: This single-center retrospective study included 184 HCV patients from 2014 to 2017. We measured HCV antibody (Duo/Ab) and HCV core antigen (Duo/cAg) using the Duo assay in HCV RNA-positive samples obtained before DAA therapy. We compared Duo/cAg positivity rates according to host and viral factors. We also performed logistic regression analysis and decision tree analysis to identify independent factors and profiles for Duo/cAg false-negative results, respectively. Results: Duo/Ab positivity rates were 100%, and Duo/cAg positivity rates were 78% in all subjects. Duo/cAg positivity rates were 40.0%, 78.6%, and 92.9% at HCV RNA levels <=4.9, 5.0-5.9, and >=6.0 log IU/mL, respectively (p<0.0001). There were no significant differences in Duo/cAg positivity rates by gender, age, body mass index, ALT >30 U/L, and HCV genotype. In multivariate analysis, the HCV RNA level (Unit -1.0 log IU/mL, OR 5.49, CI 3.12-10.56, p<0.0001) was the only independent factor associated with Duo/cAg false-negative results. Decision tree analysis revealed that HCV RNA >=5.7 log IU/mL was the profile associated with the lowest false-negative rate (7.4%). In contrast, HCV RNA <4.4 log IU/mL was the profile associated with the highest false-negative rate (100%). Conclusion: The Duo assay identified approximately 80% of HCV carriers without HCV RNA measurement, regardless of patient background, providing substantial clinical, economic, and time-saving benefits. However, clinicians should be aware of limitations in patients with low HCV RNA levels.
