[1] Univ Zurich, Epidemiol Biostat & Prevent Inst, Zurich, Switzerland
[2] Clin Barmelweid, Dept Pulm Med, Barmelweid, Switzerland
[3] Berner Reha Zentrum Heiligenschwendi, Heiligenschwendi, Switzerland
[4] Zurcher RehaZentrum Wald, Wald, Switzerland
[5] Kantonsspital Winterthur, Dept Pneumol, Winterthur, Switzerland