[1] Ghent Univ Hosp, Dept Otorhinolaryngol, Upper Airway Res Lab URL, B-9000 Ghent, Belgium
[2] Helsinki Univ Hosp, Helsinki, Finland
[3] Charite, Berlin, Germany
[4] Univ Amsterdam, Acad Med Ctr, NL-1105 AZ Amsterdam, Netherlands
[5] Hosp Clin Barcelona, Barcelona, Spain
[6] Karolinska Inst, Stockholm, Sweden
[7] Malmo Univ Hosp, Malmo, Sweden
[8] UCL, London WC1E 6BT, England
[9] Univ Lodz, PL-90131 Lodz, Poland
[10] Jagiellonian Univ, Sch Med, Krakow, Poland
[11] Med Univ Warsaw, Warsaw, Poland
[12] Swiss Inst Allergy & Asthma Res SIAF, Davos, Switzerland
[13] Univ Genoa, Dept Internal Med, I-16126 Genoa, Italy
[14] Univ Hosp, Montpellier, France
[15] INSERM, Montpellier, France
[16] Univ London Imperial Coll Sci Technol & Med, Natl Heart & Lung Inst, London, England