Inhaled corticosteroids have become an integral part of asthma management. Multiple studies have shown that inhaled corticosteroids may improve pulmonary function and reduce symptoms within weeks of starting therapy. These medications also decrease airway hypersensitivity gradually over time, and this effect has been shown to last for at least one year. The results of studies of the effectiveness of inhaled corticosteroids in the treatment of chronic obstructive pulmonary disease (COPD) are conflicting. However, no studies have observed whether the benefit of inhaled corticosteroids lasts over a prolonged period. Douma and associates studied the effectiveness of inhaled corticosteroids in patients with asthma and COPD over a prolonged period and sought to determine whether those who did not respond to the initial dosage would benefit from an increase in the dosage.

Fifty-eight patients enrolled in a previous three-year study reviewing the effectiveness of asthma treatment were invited to participate in an extension of the study for an additional 2.5 years. The patients were treated with ter-butaline, 500 mcg four times per day, and beclomethasone dipropionate, 200 mcg four times per day. If the forced expiratory volume in one second (FEV₁) decreased 50 mL or more per year during the first phase of the study, the patient's dosage of beclomethasone was increased to 500 mcg three times per day. Outcomes measured included the impact of the treatment on pulmonary function studies, which were performed every six months, and the number of exacerbations. Exacerbations were defined as increased cough, wheezing, and/or dyspnea that required the use of a rescue inhaler more than four times per day.

After the initial improvement, the mean decline in FEV₁ in the patients receiving the standard dosage of beclomethasone was 28 mL per year, while the peak expiratory flow rate declined 0.6 L per minute per year. These declines are similar to those in the general population. In the patients without an initial response to beclomethasone treatment who were then given the higher dosage, no improvement was seen in any of the outcomes measured.

The authors conclude that the initial improvement in lung function with the addition of beclomethasone to the treatment regimens of patients with asthma and COPD were maintained for more than five years in patients with an initial response to treatment. Lung function in this group declined at the same rate as in the general population. Patients who did not respond to the standard dosage of beclomethasone received no benefit from an increased dosage.