Early dynamics of viremia in patients with genotype 1b chronic hepatitis C: Peg-IFNα2a shows earlier viral decline than peg-IFNα2b in combination therapy with ribavirin

Background: We aimed to assess differences in early viral dynamics following treatment with either peg-IFNα2a or peg-IFNα2b in combination with ribavirin in patients with chronic genotype 1b HCV infection. Material/Methods: Sixty-one patients in the peg-IFNα2a + ribavirin treatment (group α2a) and 88 patients in the peg- IFNα2b + ribavirin treatment (group α2b) were retrospectively analyzed. The early dynamics of HCV RNA over 12 weeks were evaluated. Sustained virological response (SVR) was defined as undetectable HCV RNA at week 24 after end of therapy. First- (day 0-1) and second-phase (day 1-28) viral decline rates were calculated in accordance with theoretical formulae. Results: Baseline HCV RNA concentrations were almost similar between the 2 groups. In group α2a, viral decline was significantly greater than in group α2b at weeks 4, 8, and 12. In group α2a, viral decline was significantly greater in SVR patients than in non-SVR patients at week 2, whereas significantly greater viral decline in SVR patients was found during weeks 1-12 in group α2b. The first-phase viral decline rate was significantly larger in group α2a than in group α2b (1.31±0.84 vs. 0.70±0.97 log IU/mL/day; p<0.0001). Within SVR patients, first-phase viral decline rate was significantly larger in group α2a compared with group α2b (1.45±0.85 vs. 0.78±1.0 log IU/mL/day; p<0.0001). Second-phase viral decline rate was comparable between the groups. Conclusions: Peg-IFNα2a showed earlier viral decline than peg-IFNα2b and the difference was obvious, especially in the first-phase viral decline.