Early virological response (EVR) at weeks 12, end of treatment virological responses (ETR: weeks 24, 36, and 48 after therapy in groups A, B, and C, respectively), and sustained virological response (SVR: 48 weeks after completion of therapy). (A) Comparison of outcome of treatment in the three patient groups: group A, peginterferon alpha-2b (PEG-IFN-α-2b) plus ribavirin (n = 95) for 24 weeks; group B, PEG-IFN-α-2b plus ribavirin for 36 weeks (n = 96), and PEG-IFN-α-2b plus ribavirin for 48 weeks (n = 96). (B) Percentage of patients achieving early virological response at week 12 and sustained virological response to the different treatment regimen in genotype 4.