To the Editor:
In a recent issue of theEuropean Respiratory Journal, DeBoecket al.1provided a systematic review of the clinimetric properties of cystic fibrosis transmembrane conductance regulator (CFTR) biomarkers, giving supporting evidence for promoting these biomarkers as surrogate end-points. The authors are to be congratulated not only for having collected exhaustive data about CFTR biomarkers and attempted to clarify their role but also for having led tremendous efforts towards standardisation of …