1. Healthcare Professions Department, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milano, Italy
2. Laboratory of Medical Statistics and Biometry, 'Giulio A. Maccacaro', Department of Clinical Sciences and Community Health, University of Milan, Milano, Italy
3. Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Cystic Fibrosis Centre, Milano, Italy
4. Department of Pathophysiology and Transplantation, University of Milan, Milano, Italy