Indices of initial hepatitis C virus RNA reduction rate to predict efficacy of interferon‐beta followed by peginterferon plus ribavirin for genotype 1b high viral load

Aim Initial hepatitis C virus ( HCV ) RNA reduction was investigated as a potential index for sustained virological response ( SVR ) in the treatment of interferon ( IFN )‐β followed by peginterferon plus ribavirin ( PEG IFN / RBV ). Methods The treatment course was retrospectively analyzed in 64 genotype 1b patients with a HCV RNA level of 5.0 logIU/mL or higher. IFN ‐β was administrated twice a day for 2 weeks followed by 24 or 48 weeks of PEG IFN / RBV . The serum HCV RNA level was measured by real‐time polymerase chain reaction before administration and at 1, 2 and 4 weeks of therapy. Results By the duration of PEG IFN administration, the SVR rates were 11% (2/18, <19 weeks), 64% (23/36, 20–24 weeks) and 40% (4/10, 25–72 weeks) ( P  = 0.0011, χ 2 ‐test). The SVR rate was high in patients in whom the HCV RNA level had decreased by 2.5 logIU/mL or greater at 1 week of IFN ‐β (29/55 [53%] vs 0/9 [0%], P  = 0.0029, χ 2 ‐test). Among these patients, the SVR rate was even higher in those with continuous reduction in the first 2 weeks after the switch to PEG IFN / RBV (27/45 [60%] vs 2/10 [20%], P  = 0.0048). Age below 65 years, no previous IFN course and good initial HCV RNA reduction were significantly associated with SVR on multivariate analysis, and the SVR rate was 95% (18/19) among these patients. Conclusion The 2.5 logIU/mL reduction in HCV RNA at 1 week of IFN ‐β and the continuous reduction just after the switch to PEG IFN / RBV are important SVR ‐predictive indices.