HCV genotype 1a shows a better virological response to antiviral therapy than HCV genotype 1b

Background: The impact of viral subtype on the rate of sustained virological response (SVR) to antiviral therapy in patients chronically infected with hepatitis C genotype 1 subtype 1a and 1b has not been extensively investigated. The aim of this study is to determine whether the HCV genotype 1 subtypes 1a and 1b respond differently to treatment with PEGylated interferon (PEG-IFN) plus ribavirin. Methods: For 48 weeks, 388 "naive" genotype 1 patients were treated weekly with PEG-IFN a-2a or PEG-INF a-2b combined with daily ribavirin (1000-1200 mg/day). The numbers of patients in whom HCV-RNA was undetectable were compared after 4 (rapid virological response, RVR), 12 (early virological response, EVR), and 48 (end treatment virological response, ETR) weeks of treatment as well as 24 weeks after the last treatment (sustained virological response, SVR). Results: The rate of SVR was higher in subtype 1a patients than subtype 1b patients (55% vs. 43%; p < 0.02). Multiple logistic regression analysis showed that infection with genotype 1a (odds ratio(OR) : 1.8; 95% confidence interval (CI): 1.4 to 4.1), age < 50 years (OR: 7.0; 95% CI 1.1 to 21.2), alanine aminotransferase level (ALT)<100 IU/ml (OR:2.1; 95% CI: 1.3 to3.5), HCV-RNA < 5.6 log(10) IU/ml (OR: 3.2; 95% CI: 2.7 to 6.9) and fibrosis score < S3 (OR: 3.8; 95% CI: 3.2 to 7.4), were all independent predictors of SVR. Conclusion: Dual antiviral therapy is more effective against HCV subtype 1a than against subtype 1b and this difference is independent of other factors that may favour viral clearance.