1 Respiratory Unit and Adult Cystic Fibrosis Center, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy.
2 Department of Internal Medicine, Section of Pulmonary, Critical Care Medicine, Center for Pulmonary Infection Research and Treatment, Yale School of Medicine, New Haven, CT, USA.
3 Clinical Epidemiology and Medical Statistics Unit, Department of Medical, Surgical and Experimental Sciences, University of Sassari, Sassari, Italy.
4 Department of Medicine, Division of Pulmonary and Critical Care Medicine, South Texas Veterans Healthcare System and UT Health San Antonio, San Antonio, TX 78258, USA. Electronic address: restrepom@uthscsa.edu.