Risk factors associated with irreversible airway obstruction in nonsmoking adult patients with severe asthma.

Persistent airways obstruction (PAO) may affect some patients with severe asthma and may significantly worsen the prognosis. This study was designed to detect risk factors associated with persistent airflow limitation in nonsmoking adult patients with severe asthma. A total of 68 adults with severe asthma were recruited and followed prospectively for four to six weeks during the stable phase of disease. For all patients, at every visit spirometry with reversibility test was performed. Based on the results, patients were stratified into group 1 (reversible obstruction) or group 2 (PAO). In both cohorts, associations of postbronchodilatator forced expiratory volume in one second/forced vital capacity ratio (FEV1/FVC) with patients' age, gender, asthma duration, history of atopy and allergy, family history, medications, frequency of previous exacerbations, infections, hospitalizations, and artificial ventilation due to the asthma attack-related respiratory failure were investigated. Using a univariate logistic regression analysis, we have shown that older age, more than six exacerbations per year, artificial ventilation in the past, at least one hospitalization per year, the presence of atopic dermatitis, and exposure to domestic visible mold were all independent risk factors of PAO. Furthermore, multivariate regression analysis demonstrated that especially those with domestic exposure to visible molds, with very frequent exacerbations and with at least one hospitalization throughout the last year, were at risk for developing PAO. Domestic exposure to molds, hospitalization during the last year, and very frequent exacerbations were associated with PAO in patients with severe asthma. These factors may help in predicting fixed airflow limitation in nonsmoking patients with severe asthma.