RT Journal Article SR Electronic T1 Letter to the editor re: Assessing the validity of surrogate endpoints in the context of a controversy about the measurement of effectiveness of hepatitis C virus treatment JF BMJ Evidence-Based Medicine JO BMJ EBM FD BMJ Publishing Group Ltd SP 240 OP 240 DO 10.1136/bmjebm-2018-111072 VO 23 IS 6 A1 Ronald L Koretz A1 Janus Christian Jakobsen A1 Christian Gluud YR 2018 UL http://ebm.bmj.com/content/23/6/240.abstract AB