Conflict of interest: T. van der Veer declares support for the present study from Chiesi Pharmaceuticals (provision of study medication; no payments and no other support provided). J.M. de Koning Gans declares support for the present study from Chiesi Pharmaceuticals (provision of study medication; no payments and no other support provided). G.J. Braunstahl declares grants or contract funds paid to their institution by GlaxoSmithKline, AstraZeneca and Sanofi, consulting fees from Sanofi, GlaxoSmithKline, ALK Abello and AstraZeneca, and payment or honoraria from Chiesi, ALK Abello, GlaxoSmithKline and TEVA, all in the 36 months prior to manuscript submission; and holds unpaid roles as the Chair of the Asthma Section of NVALT and an editorial board member of NTvAAKI. L.S.J. Kamphuis declares payment from Chiesi for developing e-learning materials about non-CF bronchiectasis, in the 36 months prior to manuscript submission. J.G.J.V. Aerts declares payment of speaker's fees from Eli Lilly, Merck Sharp & Dohme and BIOCAD, and participation on data safety monitoring boards or advisory boards for Eli Lilly, Amphera, BIOCAD and Merck Sharp & Dohme, all in the 36 months prior to manuscript submission; in addition, they have patents planned, issued or pending with Pamgene and Amphera, holds stock in Amphera, and also declare board membership of the International Association for the Study of Lung Cancer. M.M. van der Eerden declares support for the present study from Chiesi Pharmaceuticals (provision of study medication; no payments and no other support provided). All other authors declare no competing interests.