The prebronchodilator FEV1 value improved in both the placebo- and budesonide-treated populations but significantly more so with budesonide treatment. The beneficial effect of budesonide is consistent with many previous studies demonstrating an improvement in prebronchodilator FEV1 over time with inhaled corticosteroids. The improvement in the placebo-treated group is likely due to the either the benefit that patients achieve from just being enrolled in clinical trials (the Hawthorne effect), or the fact that patients were allowed to be treated with other antiasthma medications, including inhaled or systemic corticosteroids, during the study, at the investigator’s discretion, to achieve asthma control (indeed, by the end of year 1, 21.4% of placebo-treated patients had been administered a nonstudy, inhaled or systemic corticosteroid treatment), or a combination of these two effects. Link
In the planning of this study, the effect of inhaled budesonide on the postbronchodilator FEV1 was used as evidence that the inhaled corticosteroid influenced processes leading to the decline in lung function. The CAMP trial, in which asthmatic children were enrolled with a mean duration of asthma of 5.5 years and with approximately 300 patients in each treatment group, did not demonstrate an effect of treatment for 4 years with inhaled budesonide on the postbronchodilator FEV1 when compared to placebo. As a result, the investigators concluded that inhaled corticosteroids did not influence airway remodeling in asthma.
In contrast, the present, much larger study did demonstrate a statistically significant, almost 1%, difference in the postbronchodila-tor FEV1 between the budesonide and placebo treatment groups. This suggests that early introduction of inhaled corticosteroids in newly diagnosed asthma can partially prevent the airway remodeling and its clinical consequence, loss in postbronchodi-lator FEV1. The finding that the treatment effect was more marked in adults (> 18 years old), who received 400 ^g/d of budesonide (42% less decline), than in children < 11 years old, who received 200 ^g/d of budesonide (21% less decline), suggests that the dose of inhaled budesonide may be important. The difference between the budesonide and the placebo treatment groups lessened over the 3 years of the study. This is likely related to the fact than > 25% of patients in the placebo arm of the study had been started on additional inhaled corticosteroids by the end of the 3 years of the study.