Persistent Airflow Obstruction: A Marker of a Severe Asthma Cohort – Inflammatory, Functional and Pathological Features

In our previous severe asthma cohort, 82% had fixed obstruction. Although they had greater airway smooth muscle area with decreased periostin, inflammation and remodeling weren’t associated with symptom control. High-resolution computed tomography (HRCT) and measures of small airways could be important tools for exploring asthma severity. Our aim was to describe characteristics associated to airflow obstruction in our non-controlled severe asthmatics according to obstruction profile. Persistent obstruction subgroups were also evaluated comparing disease severity. Methods: Patients were evaluated using asthma control questionnaire, induced sputum, spirometry, plethysmography, and Single Breath N2 washout test, at baseline, after oral corticosteroid (OC) and at the end of the treatment. They also underwent thorax HRCT and bronchoscopy with endobronchial biopsy. Results: Sixty-two were included and 77.4% classified as having persistent obstruction; 75% and 25% with moderate and severe obstruction, respectively. Pulmonary function values (FEV1) improved in both subgroups, except in severe. Patients with bronchial thickening, according to RB1 WA% and pi10, had significantly higher airway smooth muscle area. Conclusion: Patients with severe obstruction had greater lung function impairment, no response to OC or bronchodilator. This could be explained by airway remodeling characterized by higher airway smooth muscle area and bronchial thickness assessed by thorax HRCT.