The purpose of the study is to investigate if the duration of treatment of hepatitis C with pegylated interferon and ribavirin can be individualized on the basis of how fast the hepatitis C virus concentration in the blood decreases, and if this is more cost-efficient than standard treatment.

The current standard regimen for patients with chronic hepatitis C virus (HCV) infection, i.e., 48 weeks of pegylated interferon and ribavirin, needs to be further improved because of high costs and side-effects; in addition, the treatment is curative in only 50% of patients with genotype 1 of HCV. According to the current guidelines treatment with pegylated interferon and ribavirin is given for 24, 48 or 72 weeks depending on the time point when HCV-RNA becomes undetectable (week 4, 12 or 24). Patients with a very poor response may also be identified by applying a stopping rule at week 12 and 24. Still, most patients are treated for 48 weeks and a substantial number of those relapse after discontinuation.

In this study, standard treatment is compared with "tailored treatment", when the treatment duration is based on the time point when HCV RNA level is calculated to be 1 copy/mL, according measurements of HCV RNA on day 14, 21, 28 and 49. This arm also includes an earlier stopping rule: If the HCV RNA does not decline significantly between day 14 and 28, treatment is stopped after 5 weeks.

The advantage of tailored treatment is hypothesised to be that unnecessary side-effects and costs are avoided by an earlier identification of non-response and a treatment duration that is optimised for each patient.

Inclusion Criteria:

• Anti-HCV positive for > 6 months
• Genotype 1
• Clinical indication for treatment, preferably a liver biopsy showing significant inflammation and/or fibrosis
• Negative pregnancy test (for fertile women)

Exclusion Criteria:

• Pregnancy or breast-feeding
• Antiviral or immune modulating treatment the last 6 months
• Hepatitis B or HIV infection (HBsAg, anti-HIV)
• Other significant chronic liver disease
• History of bleeding esophageal varices or other signs of decompensation
• Neutrophiles < 1.0 x 109/L or platelets < 50 x 109/L. S-creatinine > 2 x ULN
• History of severe psychiatric disorder
• Autoimmune disease, severe heart disease, previous organ or stem cell transplantation, malignancy, thyroid disease, severe retinopathy
• Drug abuse, current or during the last year