Difference in time-course of improvement in asthma control measures between budesonide and budesonide/formoterol

Combinations of inhaled corticosteroids (ICS) and inhaled long-acting beta₂-agonists (LABA) have become widely used for the initiation of maintenance treatment for asthma. However, it has not been fully elucidated whether ICS/LABA alters the time-course of different control outcome measures in steroid-naive patients with asthma compared to the treatment with ICS alone.We compared the time-response in Asthma Control Questionnaire (ACQ), forced expiratory volume in 1 s (FEV1), exhaled nitric oxide fraction (FE_NO), and airway responsiveness to methacholine (PD₂₀₀) between budesonide (BUD) and budesonide/formoterol (BUD/FM).BUD/FM therapy significantly improved the ACQ score at week 2 and week 4 (p < 0.01 and p < 0.05), and increased FEV1 and the methacholine threshold at week 8 and week 24 (all p < 0.05) compared to BUD alone. A logistic function model showed that the BUD/FM combination significantly improved ACQ, FEV1, FE_NO and PD₂₀₀ at a faster rate than BUD over 24 weeks (p < 0.001 for ACQ, FEV1, PD₂₀₀, and p < 0.05 for FE_NO, z-test). A significant variance in the time-response was also found in the outcomes of the two treatment groups (FE_NO and ACQ > FEV1 and PD₂₀₀, p < 0.001, z-test).The present study provides evidence that ICS/LABA combination therapy results in a more rapid improvement in asthma symptoms, lung function, and airway inflammation compared to ICS monotherapy in steroid-naive patients with asthma.