Utility of lung clearance index in CF: What we know, what we don't know and musings on how to bridge the gap.

Competing Interests: Disclosures of Competing Interest Prof. Jane Davies has performed clinical trial leadership roles, educational and/ or advisory activities for the following: Abbvie, Algipharma AS, Bayer AG, Boehringer Ingelheim Pharma GmbH & Co. KG, Eloxx, Enterprise, Galapagos NV, ImevaX GmbH, Ionis, Nivalis Therapeutics, Inc., Novartis, ProQR Therapeutics III B.V., Proteostasis Therapeutics, INC., Pulmocide Raptor Pharmaceuticals, Inc, Vertex Pharmaceuticals. Clare Saunders and Christopher Short have no disclosures of interest.