[1] Haugesund Hosp, Dept Med, N-5104 Haugesund, Norway
[2] Univ Bergen, Sect Thorac Med, Inst Med, Bergen, Norway
[3] Haukeland Hosp, Clin Res Ctr, N-5021 Bergen, Norway
[4] Univ Bergen, Res Grp Lifestyle Epidemiol, Dept Publ Hlth & Primary Hlth Care, Bergen, Norway
[5] Haukeland Hosp, Dept Thorac Med, N-5021 Bergen, Norway