Serum hepatitis C virus RNA level as a predictor of subsequent response to interferon‐α therapy in Japanese patients with chronic hepatitis C

Serum hepatitis C virus (HCV) RNA level has been shown to be a good predictor of subsequent response to interferon‐α (IFN) therapy in US patients in whom genotype 1a/1b are both predominant. To determine whether serum HCV RNA level is a predictor of subsequent response to IFN in Japanese patients or not, appropriately collected pre‐IFN therapy serum samples from 35 Japanese patients with chronic HCV infection were studied. Serum HCV RNA level and HCV genotype were determined and correlated with the subsequent response to IFN. Response to IFN was defined by serum alanine transaminase level: complete and sustained response (n = 15), complete response followed by relapse (n = 10), and no response (n = 10). Patients with complete and sustained response had lower pre‐IFN serum HCV RNA level (median: RT‐PCR+, bDNA‐) compared to the complete response to relapse group (median: 5.25 × 10⁶ genome equivalent/ml [eq/ml], P < 0.001) and the no response group (median: 10.63 × 10⁶ eq/ml, P < 0.001). Seven (46.7%) of the complete and sustained response patients had HCV genotype 2a and three patients had a mixture of genotypes 1b and 2a. In contrast, all 10 patients in the complete response to relapse group had genotype 1b whereas 8 of 10 patients in the non‐response group had genotype 1b and 2 had genotype 2b. The patients with HCV genotype 2a had lower serum HCV RNA level than those with 1b (P = 0.002). When the HCV viremia were controlled by stratifying them into < and > 10⁶ eq/ml, patients with genotype 1 had a similar complete and sustained response rate compared to genotype 2. These data indicated that pre‐IFN serum HCV RNA is also a good predictor of subsequent complete and sustained response in Japanese patients with chronic HCV infection. © 1994 Wiley‐Liss, Inc.