Influence of the HCV subtype on the virological response to pegylated interferon and ribavirin therapy.

The hepatitis C virus genotype is considered to be the most important baseline predictor of a sustained virological response in patients with chronic hepatitis C treated with pegylated interferon and ribavirin. The influence of the subtype on the sustained virological response was investigated in patients infected with genotypes 1, 4, 5, or 6. This study was done on 597 patients with chronic hepatitis C who were given pegylated interferon and ribavirin for 48 weeks. The overall rate of sustained virological response in the 597 patients was 37.8%. Univariate analysis indicated that the sustained virological response of patients infected with subtype 1b (39%) tended to be higher than that of patients infected with subtype 1a (30.6%; P = 0.06) and it was similar to those patients infected with subtypes 4a (51.3%; P = 0.12) or 4d (51.7%; P = 0.16). Multivariate analysis indicated that five factors were independently associated with sustained virological response: the age (OR 0.97; 95% CI = 0.95-0.99), absence of cirrhosis (OR: 2.92; 95% CI = 1.7-5.0; P < 0.01), absence of HIV co-infection (OR: 2.08; 95% CI = 1.2-3.5; P < 0.01), low baseline plasma HCV RNA concentration (OR: 1.74; 95% CI = 1.2-2.6; P < 0.01), and the subtype 1b (OR: 1.61; 95% CI = 1.0-2.5; P = 0.04) or subtypes 4a and 4d (OR: 2.03; 95% CI = 1.1-3.8; P = 0.03). In conclusion, among difficult-to-treat genotypes, the subtype 1a is associated with a lower response to anti-HCV therapy than subtypes 1b, 4a, and 4d.