Host and viral characteristics affecting the response to interferon therapy in chronic hepatitis C.

Objective: To define parameters determined before and after 4 weeks of interferon therapy (3 MU three times per week for 24 weeks) which could be reliable predictors of a response to therapy.
Patients: Thirty-four patients with chronic hepatitis C virus (HCV) infection were investigated prospectively.
Methods: A complete response was defined as the normalization of serum alanine aminotransferase levels (ALT) at the end of treatment. The genotype of HCV was determined and the level of HCV-RNA was quantitated both before and after 4 weeks of treatment.
Results: After 4 weeks, 16 out of 20 responders [95% confidence interval (CI) 54-94%] and two out of 14 non-responders (95% CI 2-44%) normalized their ALT levels (P = 0.0002). The prevalence of genotype 1b was significantly (P < 0.04) higher among non-responders (eight out of 10; 95% CI 44-92%) than in responders (four out of 18; 95% CI 4-40%). Before treatment, the viraemia determined by branched DNA was significantly lower in responders than in non-responders (46.4 versus 116 x 10(5) eq virus/ml). After 4 weeks of treatment, the level of viraemia in responders was still significantly lower than that in non-responders (22.8 versus 66 x 10(5) eq virus/ml). In responders, a significant decrease in the level of viraemia was observed after 4 weeks of treatment.
Conclusion: In a stepwise regression analysis only age and the normalization of ALT levels after 4 weeks of treatment were predictive of response to interferon at the end of treatment.