[1] Uppsala Univ, Dept Womens & Childrens Hlth, Uppsala, Sweden
[2] Lund Univ, Dept Resp Med & Allergol, Lund, Sweden
[3] Charles Univ Prague, Fac Med 1, Dept Resp Med, Prague, Czech Republic
[4] Thomayer Hosp, Prague, Czech Republic
[5] Resp Effectiveness Grp, Ely, Cambs, England
[6] German Ctr Lung Res, Airway Res Ctr North, Lung Clin Grosshansdorf, Pulm Res Inst, Grosshansdorf, Germany
[7] Univ Oxford, Resp Med Unit, Oxford, England
[8] Univ Oxford, Oxford Resp NIHR Biomed Res Ctr, Nuffield Dept Med, Oxford, England
[9] Univ Verona, Dept Surg Dent Paediat & Gynaecol, Paediat Sect, Verona, Italy
[10] Univ Aberdeen, Inst Appl Hlth Sci, Ctr Acad Primary Care, Aberdeen, Scotland
[11] Observat & Pragmat Res Inst, Singapore, Singapore
[12] Univ Paris 05, Hop Cochin, Serv Pneumol, Paris, France
[13] Fdn Jimenez Diaz, Allergy Div, Madrid, Spain
[14] Univ Southampton, Primary Care & Populat Sci, Southampton, Hants, England
[15] Imperial Coll London, Natl Heart & Lung Inst, Airway Dis Sect, London, England
[16] Royal Brompton Hosp, London, England