CONTINUOUS AND ON DEMAND USE OF BRONCHODILATORS IN PATIENTS WITH NONSTEROID DEPENDENT ASTHMA AND CHRONIC-BRONCHITIS - 4-YEAR FOLLOW-UP RANDOMIZED CONTROLLED-STUDY

Background. A previous two-year study of continuous and on demand bron chodilator therapy in patients with moderate asthma and chronic bronch itis showed a deterioration in lung function in those on continuous th erapy. Aim. A two-year follow-up study was undertaken of patients who had been shown in the previous study to have non-steroid dependent (mi ld) asthma and chronic bronchitis, in order to investigate the effect of continuous and on-demand treatment with bronchodilator therapy. Met hod. Patients for the study were drawn from 29 general practices in th e catchment area of the University of Nijmegen, the Netherlands. A tot al of 83 patients (27 with asthma and 56 with chronic bronchitis) were selected from a group of 160 patients who had completed the previous two-year bronchodilator trial. During these first two years the select ed subjects had been shown to be non-steroid dependent (no rapid decli ne in lung function and a low number of exacerbations of their conditi on per year), and they were followed up for another two years of treat ment with bronchodilator therapy. At the start of the four-year study, patients were randomly assigned to one of two parallel treatment grou ps: continuous treatment (dry powder inhalations of either salbutamol 1600 mu g or ipratropium bromide 160 mu g daily) or treatment on deman d (only during exacerbations or periods of dyspnoea). Outcome paramete rs were the annual decline in lung function, changes in peak flow rate , bronchial hyper-responsiveness, exacerbation rate, respiratory sympt oms and reported health. Results. After correction for possibly confou nding variables and for regression to the mean, the decline in lung fu nction was 49 ml year(1) in patients taking bronchodilators continuous ly and 51 ml year(1) in patients using bronchodilators on demand, irre spective of the drug used. Continuously treated patients, whether suff ering from asthma or chronic bronchitis, did not differ from patients treated on demand with respect to mean morning peak flow rate, diurnal (and week to week) Variation of the peak flow rate, bronchial hyper-r esponsiveness, exacerbation rate and reported health. There was no dif ference between the long-term effects of salbutamol and ipratropium. C onclusion. Continuous use of bronchodilators over four years in patien ts with non-steroid dependent asthma or chronic bronchitis does not in crease the decline in lung function which had been observed previously in patients with moderate asthma or chronic bronchitis during two yea rs of continuous treatment with bronchodilators.