1 Department of Public Health, University of Liège, Belgium. Electronic address: glouis@uliege.be.
2 Department of Pneumology, GIGAI3, University of Liège, Belgium.
3 Department of Public Health, University of Liège, Belgium.
4 Department of Community Medicine, Information and Health Decision Sciences; Faculty of Medicine, University of Porto, Porto, Portugal.
5 Institute of Allergology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany; Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Allergology and Immunology, Berlin, Germany; University Hospital Montpellier, France.
6 Croix Rousse University Hospital, Lyon, France & INSERM U-1290, Lyon, France.