Ribavirin dosage in patients with HCV genotypes 2 and 3 who completed short therapy with peg-interferon alpha-2b and ribavirin.

Background: The optimal dose of ribavirin to be used in combination with Peg-IFN in patients with HCV genotypes 2 and 3 undergoing short treatment has not been established.
Aim: To explore the relationship between starting ribavirin doses, expressed as mg/kg body weight and both rapid viral response at treatment week 4 (RVR) and sustained virological response (SVR) in patients treated for 12-14 weeks with peg-interferon alpha-2b and ribavirin.
Methods: A post hoc analysis of data collected from two multicenter clinical trials was performed. Multiple regression analyses were employed to identify independent baseline and on-treatment predictors of RVR and SVR. For each dose of ribavirin, the empirical estimated probability of response was computed and the continuous exposure index was dichotomized by using a recursive partitioning and amalgamation method.
Results: A nonlinear relationship was ascertained between ribavirin dose and RVR, but not SVR. A dose of 15.2 mg/kg was selected as the best splitting value for discriminating RVR vs. non-RVR. Regression analysis identified low baseline viraemia, genotype 2 and high ribavirin dose as independent prognostic factors for RVR. The likelihood of an SVR was not correlated with baseline ribavirin dose, but was independently predicted by adherence to the full dose throughout treatment and normal platelet counts.
Conclusions: Starting high ribavirin doses appears capable of increasing the rate of RVR in patients with HCV genotypes 2 and 3 undergoing short treatment. Maintenance of the full planned dose throughout treatment is essential for achieving optimal SVR rates.