Is Delayed Introduction of Inhaled Corticosteroids Harmful in Patients With Obstructive Airways Disease (Asthma and COPD)?

The institution of inhaled corticosteroids is generally advocated for effective treatment of patients with asthma. It is yet unknown what is the best time to start inhaled corticosteroid therapy and especially whether delayed introduction is harmful. In a previous study in patients with asthma and COPD, we found that 2.5 years of treatment with a β2-agonist plus inhaled corticosteroid (BA+CS) was more effective in improving the FEV1 and the provocative concentration of histamine causing a 20% reduction in FEV1 (PC20) than treatment with a β2-agonist plus anticholinergic (BA+AC) or placebo (BA+PL). We extended this study with 6 months to investigate whether delayed introduction of inhaled CS therapy (800 pg beclomethasone dipropionate) in the groups previously not treated with inhaled CS (BA±AC) could also improve FEV1 and PC20 to the same degree. A distinction was made between patients with predominantly asthma (high baseline reversibility, ΔFEV1 ≥9% of predicted), and predominantly COPD (low baseline reversibility, AFEV1