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Inflammatory phenotype classification using induced sputum appears attractive as it can be applied to inflammation-based management of the patients with asthma. The aim of the study was to determine the reproducibility of inflammatory phenotype over time in patients with asthma. In 66 adults asthma was categorized as steroid-naïve (SN,n=17), mild to moderate (MMA,n=33), and refractory treated with oral corticosteroids (RA,n=16). Clinical assessment, skin prick testing, spirometry, and two sputum inductions in 4–6-week interval were done. Inflammatory phenotypes were classified as eosinophilic (EA), consisting of eosinophilic and mixed granulocytic phenotypes, and noneosinophilic (NEA) consisting of paucigranulocytic and neutrophilic phenotypes. During study asthma treatment remained constant. In SN group 25% of patients changed phenotype from EA to NEA and 44% changed phenotype from NEA to EA. In MMA group 26% of patients changed phenotype from EA to NEA and 50% changed phenotype from NEA to EA. In 29% of RA patients inflammatory phenotype changed from EA to NEA and in 22% it changed from NEA to EA. Inflammatory classification, using induced sputum, is not fully reproducible in adults with asthma in short-term evaluation. EA seems to be more stable phenotype across all subgroups whereas NEA remained stable only in RA group.

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.