What are the clinical features associated with Small-Airway Dysfunction in Asthma?
Published online: November 11, 2019
The involvement of small bronchial airways (internal diameter < 2 mm) is often associated with poorer asthma control and frequently overlooked in patients with asthma. In fact, conventional spirometry measurements, including forced expiratory flow at 25% to 75% of forced vital capacity (FEF25-75%), reflect mostly variability of airway obstruction and are unable to sensitively evaluate small airways. Impulse oscillometry (IOS) is a simple and noninvasive method based on the forced oscillation technique, for the detection of small-airway dysfunction (SAD).
In a paper recently published in The Journal of Allergy and Clinical Immunology: In Practice, Cottini and colleagues characterized SAD in a cohort of community-treated patients with asthma and identified the baseline clinical predictors that may help to distinguish patients with SAD among other patients with asthma.
The authors found that SAD was present in 62% of the cohort. The subjects with SAD had less well-controlled asthma according to the Global Initiative for Asthma (GINA) definition, and used higher mean inhaled corticosteroid dosage compared with patients without SAD. Increased fractional exhaled nitric oxide (FeNO), female sex, exercise-induced asthma symptoms, overweight, asthma-related night awakenings, smoking, and older age were independently associated with SAD in patients with community-managed asthma. A classification tree analysis confirmed most of these associations, showing that most of these variables have potential for clinical use in distinguishing patients with SAD from those without it.
Overall, these clinical features may be of help in distinguishing subjects with SAD within patients with asthma, especially when IOS can be performed.
The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.