1 Clinical Epidemiology and Medical Statistics Unit, Department of Biomedical Sciences, University of Sassari - Research, Medical Education and Professional Development Unit, AOU Sassari, Sassari, Italy.
2 Scottish Centre for Respiratory Research, University of Dundee, Dundee, UK.
3 Department of Pathophysiology and Transplantation, University of Milan, Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico, Milan, Italy. [email protected].