1. Department of Medicine, Respiratory Medicine Unit and Section of Internal Medicine, University of Verona and Azienda Ospedaliera Universitaria Integrata of Verona, Verona, Italy
2. Department of Medicine and Surgery, Respiratory Disease and Lung Function Unit, University of Parma, Parma, Italy
3. Pneumology Department, Clinic Institute of Thorax (ICT), Hospital Clinic of Barcelona - Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) - University of Barcelona - Ciber de Enfermedades Respiratorias (CIBERES), Barcelona, Spain