Clinical and Demographic Characteristics of Participants.

aDetermined by Ct scan.bLung Volume Reduction Surgery (LVRS).cPercentage of Forced expiratory volume (FEV1) in one second is *significantly different (pdPacks per years (PPY), quitting time (QT) and age values are similar among the three groups.eQuitting time: continue time without smoking since quitting.f, The patients had no history of allergy or asthma and had not received oral/systemic or inhaled corticosteroids during the last six months. At the time of study, all patients were free of acute symptoms suggestive of upper or lower respiratory tract infection in the 6 weeks preceding the study.