BACKGROUND: This study was undertaken to investigate the predictive factors of sustained viral response in roferon- A or pegasys treated chronic hepatitis C patients after logis- tic regression analysis of the factors that might be associated with the therapeutic effects of interferon (IFN). METHODS: All patients enrolled into this randomized, open and multi-center controlled trial were divided into two groups randomly and treated with pegasys and roferon- A for 24 weeks, then followed up for another 24 weeks. Be- fore treatment, hepatitis C virus (HCV) genotype was de- termined, and HCV-RNA in serum was detected before and at the end of treatment and follow-up. HCV-RNA turning negative was considered the major index for evaluat- ing the therapeutic effect. The clinical characteristics inclu- ding gender, age, infection route of HCV, treatment with IFN, platelet count, AST/ALT ratio and treatment drugs were analyzed by logistic regression. RESULTS: Intention to treat (ITT) and per-protocol (PP) population groups have 208 and 197 patients respectively. In the PP group, after treatment for 24 weeks, the response rates of female patients aged less than 50 years, infected through non-transfusion, relapsed after IFN treatment, and presented with a AST/ALT ratio sgl, virus load less than 8 × 105 IU/ml, and non genotype 1 HCV infection, and treated finally with pegasys were higher than those of male pa- tients, aged more than 50 years, infected by transfusion, treated firstly with IFN, presented with a AST/ALT rations 1, virus load equal or more than 8 × 105 IU/ml, and geno- type 1 infection, and treated finally with roferon-A. But, at the end of follow-up, the patients with a AST/ALT ration 1 and virus load more than 8 ×105 IU/ml had a higher rate of sustained response than did those with a AST/ALT ratio ^1 and virus load less than 8 ×105 IU/ml. Logistic regres- sion analysis and control of the promiscuous factors showed that the genotype of HCV was not related to the response rate at the end of treatment (OR 0.604, 95% CI 0.271- 1.349, P =0.219), but was the independent predictive fac- tor of virus sustained response to IFN treatment ( OR 0.408, 95% CI 0.189-0.881, P =0.023). The form of IFN was significantly related to viral response at the end of treat- ment (OR0.105, 95% CI 0.052-0.212, P<0.001), and pe- gasys were an intensely predictive factor for sustained re- sponse (OR 0.255, 95% CI 0. 123-0.529, P<0.001). CONCLUSION: HCV genotype and pegasys are the predic- tive factors for IFN response to the IFN treatment of pa- tients with chronic hepatitis C. BACKGROUND: This study was undertaken to investigate the predictive factors of sustained viral response in roferon-A or pegasys treated chronic hepatitis C patients after logistic regression analysis of the factors that might be associated with the therapeutic effects of interferon (IFN). METHODS : All patients enrolled into this randomized, open and multi-center controlled trial divided into two groups randomly and treated with pegasys and roferon-A for 24 weeks, then followed up for another 24 weeks. Be- fore treatment, hepatitis C virus ( HCV) genotype was de- termined, and HCV-RNA in serum was detected before and at the end of treatment and follow-up. HCV-RNA turning negative was considered the major index for evaluat- ing the therapeutic effect. The clinical characteristics inclu - ding gender, age, infection route of HCV, treatment with IFN, platelet count, AST / ALT ratio and treatment drugs were analyzed by logistic regression. RESULTS: Intention to treat (ITT) and per-prot In the PP group, after treatment for 24 weeks, the response rates of female patients aged less than 50 years, infected through non-transfusion, relapsed after IFN treatment, and presented with a AST / ALT ratio sgl, virus load less than 8 × 105 IU / ml, and non genotype 1 HCV infection, and treated finally with pegasys were higher than those of male pa- tients, aged more than 50 years, infected by transfusion, treated with IFN, presented with a AST / ALT rations 1 virus load equal or more than 8 × 105 IU / ml, and geno- type 1 infection, and treated finally with roferon-A. But, at the end of follow- up, the patients with a AST / ALT ration 1 and virus load more than 8 × 105 IU / ml had a higher rate of sustained response than did those with a AST / ALT ratio ^ 1 and virus load less than 8 × 105 IU / ml. Logistic regres- sion analysis and control of the promiscuous factors showed that the genotype of HCV was not related to the response rate at the end of treatment (OR 0.604, 95% CI 0.271- 1.349, P = 0.219), but was the independent predictive fac tor of virus sustained response to IFN treatment (OR 0.408, 95% CI 0.189-0.881, P = 0.023). The form of IFN was significantly related to viral response at the end of treat- ment (OR 0.105, 95% CI 0.052-0.212, P <0.001), and pe- gasys were an intensely predictive factor for sustained re - sponse (OR 0.255, 95% CI 0.123-0.529, P <0.001) CONCLUSION: HCV genotype and pegasys are the predictive factors for IFN response to the IFN treatment of paients with chronic hepatitis C.