Changes in hepatitis C viral load during first 14days can predict the undetectable time point of serum viral load by pegylated interferon and ribavirin therapy

Aim: In the treatment of chronic hepatitis C, pegylated interferon (PEG-IFN) and ribavirin combination therapy must be continued for an adequate duration to improve the rate of sustained virological response. We attempted to predict the time point at which serum hepatitis C virus (HCV) RNA are undetectable during combination therapy. Methods: Patients with HCV genotype 1b were enrolled in a model preparation (n=35) and a validation group (n=70). All patients received PEG-IFN-α-2b/ribavirin combination therapy for at least 48weeks, and serological samples were screened a minimum of 17 times during the therapy. Serum HCV RNA were measured by the Abbott RealTime HCV assay. Using the HCV dynamics model described by Neumann etal., we used multiple linear regression analysis to select factors that affected the undetectable time point. Results: Difference in viral load between weeks 1 and 2 was the only predictive factor for the undetectable time point of serum HCV RNA (r²=0.67, P<0.0005), and we derived the following prediction equation: undetectable time point (week)=13.495×(viral load at day 14 [log IU/mL]-viral load at day 7 [log IU/mL])+25.456. The equation was applicable to the validation group. Conclusion: We created a formula for predicting the undetectable time point from viral load measurements early in PEG-IFN-α-2b/ribavirin combination therapy. An early response reflects sensitivity to therapy, and the estimation of an undetectable time point would be useful for determining the optimal duration of treatment for chronic hepatitis C patients.