AbstractThe impact of ribavirin (RBV) dosage on sustained virologic response (SVR) rates remains elusive in hepatitis C virus genotype 2 (HCV-2) rapid responders receiving 16 weeks of peginterferon (Peg-IFN) plus RBV. Treatment-naïve HCV-2 patients with rapid virologic response (RVR) received Peg-IFN alfa-2a 180 μg/week plus weight-based RBV (1,000 or 1,200 mg/day; cut-off body weight: 75 kg) for 6 weeks and then randomly received Peg-IFN alfa-2a 180 μg/week plus weight-based (1,000 or 1,200 mg/day; n = 247) or flat-dose (800 mg/day; n = 246) RBV for additional 10 weeks. The primary endpoint was SVR₂₄. Patients receiving weight-based and flat-dose RBV therapies had comparable SVR₂₄ rates (93.5% versus 91.9%, P = 0.49). The risk differences (RDs) of SVR₂₄ receiving weight-based and flat-dose RBV arms were 7.1% [95% CI: 0.7% to 13.6%] in males and −5.8% [95% CI: −12.1% to 0.5%] in females (interaction P = 0.01). The SVR₂₄ rate was higher in males receiving ≥13 mg/kg/day than those receiving <13 mg/kg/day (96.3% versus 85.1%, P = 0.001). In conclusion, Peg-IFN alfa-2a plus weight-based or flat-dose RBV for 16 weeks provides comparable SVR₂₄ rates in treatment-naïve HCV-2 rapid responders. However, males should receive weight-based RBV to achieve a high SVR₂₄ rate.