Assessment of the efficacy of reducing peginterferon alfa-2a and ribavirin dose on virologic response in Koreans with chronic hepatitis C

Background/Aims: The virologic response of Koreans to combination therapy for chronic hepatitis C is similar to westerns; however, dose modification occurs more frequently in Koreans. We evaluated the rates of peginterferon α-2a and ribavirin dose modifications and their effect on the virologic response in Koreans. Methods: Patients with detectable HCV RNA and enrolled from multicenters were treated with peginterferon α-2a (180 μg/week) and ribavirin (800 mg/day) for 24 weeks (genotype non-1, n=37) or peginterferon α-2a (180 μg/ week) and ribavirin (1,000-1,200 mg/day) for 48 weeks (genotype 1, n=55). Results: Early virologic response (EVR) and sustained virologic response (SVR) were 77.2% (genotype 1, 75%; non-1, 81%) and 66.3% (genotype 1, 56%; non-1, 81%), respectively. The frequency of dose modification was 32.6% within the first 12 weeks and 52.2% during the entire treatment period. No difference was found in SVR regardless of dose modification. However, the SVR for patients using ≥80% of the peginterferon dose was significantly higher than for those using <80% (81.3 vs. 50.0%, p=0.007), despite varying ribavirin doses. No difference was found in SVR regardless of whether the ribavirin dose was <80% or not. These results did not change based on genotype. Conclusions: We suggest that using at least 80% of the peginterferon α-2a dose in Koreans not only maintains SVR but also reduces drug side effects during the entire treatment period. A lower dose of ribavirin may be as efficacious as a standard dose.