[1] Univ Bern, Inst Social & Prevent Med, Bern, Switzerland
[2] Childrens Hosp St Gallen, Div Paediat Pulmonol, St Gallen, Switzerland
[3] Univ Bern, Childrens Univ Hosp Bern, Paediat Resp Med, Bern, Switzerland
[4] Univ Bern, Dept Paediat, Univ Childrens Hosp, Bern, Switzerland
[5] Univ Childrens Hosp Zurich, Div Paediat Pulmonol, Zurich, Switzerland
[6] Kantonsspital Aarau, Dept Paediat, Aarau, Switzerland
[7] Childrens Hosp Lucerne, Div Paediat Pulmonol, Luzern, Switzerland