Single-inhaler triple therapy improves small airway dysfunction in moderate to severe asthma and asthma-COPD overlap: a retrospective cohort study.

Medium- or high-dose fluticasone furoate (FF)/vilanterol (VI)/umeclidinium (UMEC) is associated with an improvement in forced expiratory volume in one second (FEV1), a marker of large airway dysfunction. However, the effect of FF/VI/UMEC on small airway dysfunction (SAD) remains unknown. To clarify the effect of FF/VI/UMEC on SAD in moderate to severe asthma and asthma-chronic obstructive pulmonary disease overlap (ACO) in a retrospective cohort study. Subjects included 18 moderate to severe asthma and ACO patients who switched from inhaled corticosteroid/long-acting-β2 agonist (ICS/LABA) to FF/VI/UMEC. Asthma Control Test (ACT), Asthma Control Questionnaire (ACQ), blood eosinophil counts, total IgE, fractional exhaled nitric oxide, spirometry, and oscillometry were measured and compared before and after FF/VI/UMEC treatment. Markers of SAD, including forced vital capacity (FVC), forced expiratory flow at 25-75% of FVC, respiratory system reactance at 5Hz (X5), resonant frequency, and low-frequency reactance area (AX), improved significantly after the induction of SITT, in addition to ACT, ACQ, FEV1, and FEV1/FVC. Improvements in FEV1, X5, and AX correlated with improvements in ACT, and improvements in FEV1 and FEV1/FVC correlated with improvements in ACQ. FF/VI/UMEC improved SAD, and its improvement was correlated with improved asthma control in moderate to severe asthma and ACO patients.