Phenotypic characteristics of asthma with small airways involvement

In healthy lung, distal airways represent under 25% of total airflow resistances and are the main site of airflow obstruction in asthmatics (up to 50%). Asthma is recognized as a heterogeneous disease and several asthma phenotypes have been described, however the contribution of small airways is poorly investigated. The aim of this study is to analyze the characteristics associated to the small airway phenotype among asthmatics. Our retrospective study took place from 11/2014 to 04/2015 in 2 French departments of lung diseases. In asthmatics, small airway obstruction (SAO) was defined by FEV1/FVCu003e70%, FEV1u003e80% and either RVu003epredicted value +1.64 RSD or DEM50 Among 69 asthmatics, 44 and 25 were respectively included in PAO and SAO groups. The main result was the predominance of atopy in SAO group. A family history of atopy was present in 5% and 20% of PAO and SAO patients respectively (p=0.044). A personal history of atopy was noted in 54.5% and 80% of PAO and SAO respectively (p=0.041). Additionally, SAO asthma was better controlled than PAO asthma (p=0.027). Finally, PAO was associated with more severe asthma than that observed in SAO group (p Our results demonstrate that asthma associated to SAO is predominantly linked to atopic characteristics, better controlled and less severe than PAO asthma. Taken together, these results suggest that SAO asthma may constitute a relevant asthma phenotype. However, larger and prospective studies are required.