Predictors of the efficacy of interferon therapy in chronic hepatitis C virus infection

Background & Aims: The relative role of virus load and hepatitis C virus (HCV) subtype as predictor of the efficacy of interferon (IFN) therapy is still in dispute. To resolve this issue, a multicenter, randomized, prospective study of 272 patients with chronic hepatitis C but without cirrhosis was conducted. Methods: The patients were randomly assigned to two different dose groups: 6 million units (MU) or 9 MU IFN three times a week for 6 months. Serum HCV RNA levels and HCV subtypes were determined. Results: HCV RNA negativity rate at the completion of treatment with 9 MU IFN was higher than that with 6 MU (75% vs. 44%; P < 0.05). Virus eradication at 12 months after completion of treatment was higher in the 9 MU group than in the 6 MU group (36% vs. 25%; P < 0.05), especially in patients who had an intermediate virus load (10(4)-10(5) copies/mL by Amplicor monitor assay) (52% vs. 19%; P = 0.029). Virus eradication rate in patients with serotype 2 was higher than in those with serotype 1 for both regimens (6 MU, 53% vs. 15%; 9 MU, 76% vs. 29%; each P < 0.05). Conclusions: This prospective study showed that virus load, HCV serotype, and IFN dose are important predictors of the virological response to IFN therapy but virus load is the most important factor influencing the efficacy of IFN.