Background: Chronic hepatitis C (CHC) genotypes 1 and 6 are common in Thailand and often cause cirrhosis and other complications. Treatment with peginterferon alfa plus ribavirin is currently still recommended, but it has limited efficacy, entails long duration of treatment, and results in some adverse side effects. New direct-acting antiviral agents (DAAs) are effective treatments, but they are costly and not readily available.
Objective: To evaluate the response of CHC genotypes 1 and 6 to treatment with peginterferon alfa plus ribavirin, and to find the predictive factors of treatment response.
Material and Method: Data were collected retrospectively from patients with chronic Hepatitis C genotypes 1 and 6 who were treated with peginterferon alfa plus ribavirin for 48 weeks between 2013 and 2016 at Rajavithi Hospital, Bangkok. Demographic information and laboratory data were recorded, together with details of virological data, treatment response, and treatment compliance with the 80/80/80 rule. Data analysis was performed of treatment response and its predictive factors.
Results: Seventy-one patients with a mean age 50.76+9.70 years were included, of which 71.8% were men, 55.0% were genotype 1, and 45.0% were genotype 6. Eighty-three percent of patients were aged more than 40 years, 67.6% had body mass index less than 25kg/m2, 53.5% had cirrhosis, and Hepatitis C RNA levels (HCV RNA level) of more than 400,000 iu/ml were found in 78.9% of cases. The overall Sustained Virological Response (SVR) rate was 77.5%, while genotypes 1 and 6 had SVR of 79.5% and 75%, respectively. SVR was associated with people aged more than 40 years old (p = 0.022), high baseline ALT level (p = 0.006), virological response during treatment at 12 and 24 weeks and at end of treatment (EOTR) (p = 0.019, 0.011 and 0.002 respectively), and treatment compliance (p<0.001). Multivariate analysis found that treatment
compliance with the 80/80/80 rule was the only factor associated with SVR OR = 31.5, 95% CI (6.16 to 161.15).
Conclusion: Response of CHC genotypes 1 and 6 to treatment with peginterferon alfa plus ribavirin was good. Selection of suitable patients and good compliance with treatment resulted in high SVR rates, comparable to those achieved with DAA regimens.

Keywords: Chronic hepatitis C, Genotype 1, Genotype 6, Treatment response, Sustained virological response, HCV RNA level, Transient elastography, Peginterferon alfa, Ribavirin