The effects of inhaled budesonide on lung function in smokers and nonsmokers with mild persistent asthma.

Background: Previous studies have suggested a reduced benefit from therapy with inhaled corticosteroids (ICSs) in asthmatic patients who smoke. The objective of this post hoc study was to study the effects of low-dose inhaled budesonide on lung function in smokers and nonsmokers with mild persistent asthma.
Methods: Adult patients (age, >or= 18 years) in the inhaled Steroid Treatment As Regular Therapy in early asthma (START) study, a 3-year, randomized, placebo-controlled, double-blind study, were stratified according to their smoking habits. The effects on lung function of therapy with budesonide vs placebo were compared in 492 asthmatic patients who smoked habitually and 2,432 nonsmokers.
Results: When treated with placebo, newly diagnosed asthmatic patients who smoke had a greater 3-year decline in post-bronchodilator therapy FEV(1), the change being -263.9 mL (SE, 21.8), when compared with nonsmokers on placebo, which was -180.8 mL (SE, 10.6), the mean difference being -83.1 mL (p < 0.001). Budesonide treatment was associated with a statistically significant 3-year increase in post-bronchodilator therapy FEV(1) in both groups. The effect of budesonide vs placebo was 71.5 mL (p = 0.011) in smokers and 46.5 mL (p = 0.001) in nonsmokers. The corresponding effect in pre-bronchodilator therapy FEV(1) was 118.1 mL (p = 0.002) in smokers and 72.9 mL (p < 0.001) in nonsmokers.
Conclusions: Asthmatic patients who smoke, and are not treated with ICSs, have a greater decline in lung function than asthmatic patients who do not smoke. The benefits of therapy with inhaled budesonide on preventing lung function decline are similar in smokers and nonsmokers with mild persistent asthma.