[1] Haukeland Hosp, Dept Thorac Med, N-5021 Bergen, Norway
[2] Univ Bergen, Inst Med, N-5020 Bergen, Norway
[3] Haukeland Hosp, Clin Res Ctr, N-5021 Bergen, Norway
[4] Univ Copenhagen Hosp, Rigshosp, Dept Internal Med, DK-2100 Copenhagen, Denmark
[5] Landspitali Univ Hosp, Dept Pulm Med, Reykjavik, Iceland
[6] Univ Tartu, Lung Clin, EE-50090 Tartu, Estonia
[7] Univ Hosp No Sweden, Dept Pulm Med & Allergol, Umea, Sweden
[8] Uppsala Univ, Akad Sjukhuset, Dept Med Sci Resp Med & Allergol, Uppsala, Sweden