[1] Univ Med Ctr Groningen, Dept Pulmonol, NL-9713 Groningen, Netherlands
[2] Univ Groningen, Univ Med Ctr Groningen, Dept Pulmonol, Groningen, Netherlands
[3] Univ Groningen, Univ Med Ctr Groningen, Groningen Res Inst Asthma & COPD GRIAC, Groningen, Netherlands
[4] Univ Groningen, Univ Med Ctr Groningen, Dept Epidemiol, Groningen, Netherlands
[5] Univ Med Ctr Utrecht, Dept Pulmonol, Utrecht, Netherlands
[6] Franciscus Gasthuis, Dept Pulmonol, Rotterdam, Netherlands
[7] Isala Hosp, Dept Pulmonol, Zwolle, Netherlands
[8] Univ Groningen, Univ Med Ctr Groningen, Lab Med Immunol, Groningen, Netherlands
[9] Gen Practitioners Res Inst, Groningen, Netherlands
[10] Observat & Pragmat Res Inst Pte Ltd, Singapore, NSW, Singapore
[11] Univ Groningen, Univ Med Ctr Groningen, Dept Pathol & Med Biol, Groningen, Netherlands
[12] Woolcock Inst Med Res, Glebe, NSW, Australia