Aim: To evaluate the potential value of using a serological assay to quantitate the hepatitis C virus core antigen (HCV-Ag) when monitoring patients with chronic hepatitis C being treated with direct-acting antivirals (DAAs).
Methods: Ninety-six patients treated with DAAs, either alone (91) or in combination with PEG interferon (5), were tested for HCV-RNA and for HCV-Ag at baseline and at weeks 2, 4, 8 and 12 during treatment and 12 weeks after completion. The concordance and correlation between the viral parameters as well as the respective kinetics during and after treatment were evaluated.
Results: A sustained viral response (SVR) was achieved in 82 patients (91%), whereas 11 relapsed (R) and 1 showed a virological breakthrough while receiving treatment. HCV-RNA and HCV-Ag showed good concordance (kappa = 0.62) and correlation. No significant differences between SVR and R was observed in either assay at 2 and 4 weeks after the start of treatment. At 8 weeks, HCV-Ag showed higher accuracy than HCV-RNA (AUC: 0.74 vs. 0.55) and there was a significantly greater decrease from baseline in SVR than in R (4.01 vs. 3.36 log10; p<0.05).
Conclusions: Monitoring during treatment with DAAs by using either HCV-RNA or HCV-Ag has only a limited predictive value for SVR. Since those assays are equivalent for identifying a virological relapse, HCV-Ag may be preferred from an economical and organizational perspective.