Treatment effectiveness by era. Treatment effectiveness by era. Treatment effectiveness by time period. Of all patients seen in a subspecialty hepatology clinic, 22.3% (white bar) of patients in the IFN era were treated and 12.3% achieved SVR. Seventy-seven per cent (black bar) of patients were treated and 68.5% achieved SVR in the DAA era. CHC, chronic hepatitis C; DAA, direct-acting antiviral; IFN, interferon; SVR, sustained virological response. Peter Nguyen et al. BMJ Open Gastroenterol 2017;4:e000181 © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.