Purpose / DescriptionThis very large, prospective, open-label trial enrolled 5207 hepatitis C treatment-naive patients at 236 sites in the United States to examine the impact of weight-based or flat-dose ribavirin given with peginterferon alfa-2b. Patients in the study were randomized on a 1:1 basis to receive peginterferon alfa-2b plus flat-dose ribavirin or peginterferon alfa-2b plus weight-based ribavirin. At the beginning of the trial, all patients were scheduled to recieve 48 weeks of therapy, but the protocol was amended so that patients with genotype 2 or 3 were randomized to receive either 24 or 48 weeks of therapy. Overall,  SVR24 rates were higher in patients who received weight based ribavirin compared with flat-dose ribavirin.  When analyzing for gentoype 1 patients, those who received weight based ribavirin compared with flat-dose ribavirin (34% versus 29%).  WIth genotype 2 and 3 patients, no significant differences were observed with weight-based versus flat-dose ribavirin and extending treatment to 48 weeks did not significantly improve SVR rates. This study demonstrated a benefit of using weight-based ribavirin in combination with peginterferon alfa-2b when treating patients with gentoype 1 HCV, but not with genotype 2 or 3.