[1] Univ Milan, Dept Hlth Sci, ASST Santi Paolo & Carlo, Resp Unit, Milan, Italy
[2] Univ Cattolica Sacro Cuore, Fdn Policlin Univ Agostino Gemelli IRCCS, Div Pulm Med, Rome, Italy
[3] Univ Catania, Reg Referral Ctr Rare Lung Dis, AOU Policlin San Marco, Dept Clin & Expt Med, Catania, Italy
[4] ASST Papa Giovanni XXIII, Resp Unit, Bergamo, Italy
[5] Univ Milan, Dept Hlth Sci, Milan, Italy
[6] Univ Sassari, Dept Med Surg & Expt Sci, Clin Epidemiol & Med Stat Unit, Sassari, Italy