1 Department of Pneumology, Institut Clinic de Respiratori, Hospital Clinic of Barcelona-Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), University of Barcelona (UB), Ciber de Enfermedades Respiratorias (CIBERES) Villarroel 170 (08036), Barcelona, Spain.
2 Department of Pneumology, Institut Clinic de Respiratori, Hospital Clinic of Barcelona-Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), University of Barcelona (UB), Ciber de Enfermedades Respiratorias (CIBERES) Villarroel 170 (08036), Barcelona, Spain. Electronic address: atorres@ub.edu.