Here's the one I came across, don't know if you've already read it or not. Good Luck
Impact of reducing peginterferon alfa-2a and ribavirin dose during retreatment in patients with chronic hepatitis C.Shiffman ML, Ghany MG, Morgan TR, Wright EC, Everson GT, Lindsay KL, Lok AS, Bonkovsky HL, Di Bisceglie AM, Lee WM, Dienstag JL, Gretch DR.
Hepatology Section, Virginia Commonwealth University Medical Center, Richmond, VA 23298, USA.