Conflict of interest: R. Beasley reports grants from Health Research Council of New Zealand, personal fees for consultancy from AstraZeneca, during the conduct of the study; grants and personal fees for advisory board work, consultancy and travel to meetings from AstraZeneca, grants from GlaxoSmithKline and Genentech, personal fees for advisory board work from Theravance Biopharma, outside the submitted work. Conflict of interest: I. Braithwaite reports grants from Health Research Council of New Zealand, during the conduct of the study; grants from Genentech, outside the submitted work. Conflict of interest: A. Semprini reports grants from Health Research Council of New Zealand, during the conduct of the study. Conflict of interest: C. Kearns has nothing to disclose. Conflict of interest: M. Weatherall has nothing to disclose. Conflict of interest: T.W. Harrison reports personal fees for consultancy from AstraZeneca, during the conduct of the study; personal fees for consultancy and lectures, and travel expenses reimbursement from AstraZeneca, personal fees for advisory board work from GSK, outside the submitted work. Conflict of interest: A. Papi reports personal fees for board membership, consultancy and lectures, grants for research, and travel expenses reimbursement from Chiesi, AstraZeneca, GlaxoSmithKline, Boehringer Ingelheim, Mundipharma and TEVA, personal fees for lectures and travel expenses reimbursement from Menarini, Novartis and Zambon, personal fees for board membership and consultancy from Sanofi/Regeneron, outside the submitted work. Conflict of interest: I.D. Pavord reports personal fees for lectures and advisory board work, and travel expenses from AstraZeneca, GSK, Boehringer Ingelheim and TEVA, grants and personal fees for lectures and advisory board work, and travel expenses from Chiesi, personal fees for advisory board work from Sanofi/Regeneron, Merck, Novartis, Knopp and Roche/Genentech, personal fees for lectures from Circassia and Mundipharma, grants and personal fees for advisory board work from Afferent, outside the submitted work.