Initial improvements in lung function and bronchial hyperresponsiveness are maintained during 5 years of treatment...

Treatment with inhaled corticosteroids reduces bronchial hyperresponsiveness and relieves airways obstruction in patients with asthma. Up to now, it is unknown whether initial improvements are maintained over a long period of time. Therefore, we assessed whether initial improvements in FEV(1), provocative concentration of histamine causing a 20% fall in FEV(1) (PC(20)), and peak expiratory flow (PEF) persist with a constant dose of inhaled corticosteroids. Furthermore, we investigated whether FEV(1), PC(20), PEF indexes, and symptom scores improve after increasing the dose of inhaled corticosteroids in patients who did not respond sufficiently to treatment with beclomethasone dipropionate (BDP), 800 microg/d.

Sixty-eight patients with bronchial hyperresponsiveness and airways obstruction completed a previous study on 3 years of treatment with terbutaline, 500 microg qid, and BDP, 200 microg qid. Fifty-eight of these patients participated in the current extension of another 2.5 years of follow-up. Every 6 months, FEV(1) and PC(20) were measured. Five patients dropped out of the study, one for pulmonary reasons. Forty-four patients continued treatment with BDP, 800 microg/d (BDP-800 group), and 9 patients received a higher dose of BDP (500 microg tid; BDP-1,500 group) after the first 3 years because of a rapid decline in FEV(1) (> 50 mL/yr) despite BDP treatment during the previous study period.

After the initial improvement, the mean slope of individual regression lines for FEV(1), PC(20), and morning PEF were - 28 mL/yr, - 0.01 doubling concentrations per year, and 0.6 L/min/yr, respectively, in the BDP-800 group. In the BDP-1,500 group, there were no statistically significant improvements in FEV(1), PC(20), PEF indexes, and symptom scores after increasing the dose of BDP.

We conclude that initial improvements in FEV(1), PC(20), and PEF are well preserved over 5 years in patients with obstructive airways diseases who are treated with terbutaline and BDP. In the patients who responded sufficiently to 800 microg/d of BDP, there was no accelerated decline in FEV(1) compared with the general population. Increasing the dose of BDP in a small group of patients with an accelerated fall in FEV(1) (initially treated with a moderate dose of BDP) resulted in no significant improvement in FEV(1), PC(20), PEF indexes, and symptom scores.