Extrafine ICS/LABA Versus As-Needed SABA for Small Airway Dysfunction in Symptomatic Patients With Preserved Spirometry

This study evaluates whether 4 weeks of extrafine inhaled corticosteroid/long-acting β2-agonist (beclomethasone dipropionate/formoterol fumarate, BDP/FOR) therapy improves clinical, physiological, and type 2 inflammatory outcomes compared with as-needed short-acting β2-agonist (SABA, salbutamol) alone in symptomatic patients who have preserved conventional spirometry but impulse oscillometry (IOS)-defined small airway dysfunction (SAD) and small airway reversibility (SAR) after bronchodilator inhalation. Participants were randomized 1:1 to receive extrafine BDP/FOR plus as-needed salbutamol, or as-needed salbutamol alone, for 4 weeks. Symptom score (Asthma Control Test), spirometry, IOS parameters, type 2 inflammatory biomarkers (FeNO, blood eosinophils, IgE), and rescue medication use were assessed before and after treatment.