Pulmonary Research Institute at Lung Clinic Grosshansdorf, Airway Research Center North, Member of the German Center of Lung Research, Grosshansdorf, Germany. Respiratory Effectiveness Group, Ely, UK. Department of Respiratory Medicine, Antwerp University Hospital, Edegem, Denmark. Laboratory of Experimental Medicine and Paediatrics, University of Antwerp, Wilrijk, UK. CIUSSS de L'Ouest-de-L'Île-de-Montréal, Montreal Chest Institute, Meakins-Christie Laboratories, Oscillometry Unit and Centre for Innovative Medicine, McGill University Health Centre and Research Institute, Montreal, QC, Canada. Department of Respiratory Medicine, APHP-Centre University of Paris, UMR1016, Cochin Institute, Paris, France. Section of Cardiorespiratory and Internal Medicine, Department of Medical Sciences, University of Ferrara, Ferrara, Italy. Observational and Pragmatic Research Institute, Singapore, Singapore. Centre of Academic Primary Care, Division of Applied Health Sciences, University of Aberdeen, Aberdeen, UK. Pneumology Department, Hospital Universitari Vall D'Hebron, Vall D'Hebron Institut de Recerca (VHIR), CIBER de Enfermedades Respiratorias (CIBERES), Vall d'Hebron Barcelona Hospital Campus, Passeig Vall d'Hebron 119-129, 08035, Barcelona, Spain. marcm@separ.es.