1 Respiratory Diseases Unit, Department of Medicine and Surgery, University of Milan-Bicocca Fondazione IRCCS San Gerardo, Monza, Italy. fabrizio.luppi@unimib.it
2 Division of Pulmonary Medicine, Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta and Alberta Health Services, Edmonton, Alberta, Canada
3 Respiratory Diseases Unit, Department of Medicine and Surgery, University of Milan-Bicocca Fondazione IRCCS San Gerardo, Monza, Italy