[1] Alfred Hlth, Allergy Asthma & Clin Immunol, Melbourne, Vic, Australia
[2] Monash Univ, Publ Hlth & Prevent Med, Melbourne, Vic, Australia
[3] Royal Brompton Hosp, Asthma & Allergy, London, England
[4] Imperial Coll London, Natl Heart & Lung Inst, London, England
[5] Royal Brompton Hosp, Paediat Difficult Asthma Serv, London, England
[6] Bispebjerg Hosp, Resp Res Unit, Copenhagen, Denmark
[7] Univ Copenhagen, Dept Clin Med, Copenhagen, Denmark
[8] Med Ctr Leeuwarden, Dept Resp Med, Leeuwarden, Netherlands
[9] Wythenshawe Hosp, North West Lung Ctr, Manchester, Lancs, England
[10] Cambridge Univ Hosp, Dept Resp Med, Cambridge, England
[11] Changi Gen Hosp, Dept Resp & Crit Care Med, Singapore, Singapore