Prevalence of tracheobronchomalacia and excessive dynamic airway collapse in bronchial asthma of different severity

Background: Tracheobronchomalacia (TBM) is a pathologic condition in which softening of tracheal and bronchial cartilage causes the dynamic narrowing of transverse or sagittal diameters of tracheobronchial lumen; an excessive dynamic airway collapse (EDAC) may also be associated, with a substantial invagination of the posterior membrane of trachebronchial tree. The aim of this study was to assess the prevalence of both TBM and EDAC in a population of asthmatics with different degrees of disease severity compared to a reference group of subjects without any bronchial obstruction. Methods: A cohort of 202 asthmatics was investigated by means of a dynamic flexible videobronchoscopy: 74 mild persistent (MPA - age 18–68 ys; 35 males; mean FEV1 = 88.6% pred. ± 8.3 sd); 63 moderate (MA - age 21–71 ys; 30 males; mean FEV1 = 71.3% pred. ± 9.1 sd), 65 severe asthmatics (SA - age 33–70 ys; 25 males; mean FEV1 = 48.5% pred. ± 7.6 sd), and 62 non obstructed subjects (NO - age 18–71 ys; 38 males; mean FEV1 98.6% pred. ± 2.7 sd). TBM and EDAC were classified according to FEMOS classification. Results: TBM and EDAC were observed in only 1/62 subjects (both 1.61%) of NO group, while their prevalence was 2.70% and 6.75% in MPA group; 7.93% and 19.04% in MA group; 18.46% and 69.23% in SA group, respectively. The crude prevalence of thyroid disorders in the population was 12.9%. In particular, the prevalence of thyroid disorders was significantly higher in females than in men, but 54-fold higher in females than in men in the presence of EDAC. Conclusions: 1) The prevalence of both TBM and EDAC is directly related to age, gender (females), and asthma severity; 2) EDAC is much more frequent than TBM in all asthma patients; 3) both tracheal abnormalities proved to be more represented in asthmatics with thyroid disorders, and particularly in female asthmatics with EDAC.