Background: Previous work has suggested that the long-term regular use of inhaled beta2-agonist bronchodilators might lead to a deterioration in asthma control. The aim of TRUST (The Regular Use of Salbutamol Trial) was to study the effects of regular use of inhaled salbutamol, the most widely prescribed bronchodilator in the UK, on the control of asthma.
Methods: A randomised, double-blind, placebo-controlled trial was undertaken in 983 patients with asthma being treated at least twice a week with short-acting beta2-agonist, alone or in combination with inhaled steroids (2 mg or less) daily. Patients were aged 18 years and over and were recruited from 115 general practices in the UK. 90% (881) of the patients used inhaled corticosteroid therapy, and all patients continued to use their usual inhaled beta2-agonist for symptomatic relief. Patients were randomised to receive 400 microg salbutamol or matched placebo via a Diskhaler four times per day for 12 months. The primary outcome measure was rate of exacerbations of asthma, with criteria based on data from diary cards completed daily by each patient, treatment with additional corticosteroids, or both.
Findings: There were no differences in the annual rate, timing, or duration of exacerbations between the two groups. The mean morning peak expiratory flow was similar for the two groups. The mean evening peak expiratory flow (p<0.001) and the diurnal variation (p<0.001) were greater, and the use of rescue bronchodilator was less (p<0.001), in the group receiving regular salbutamol.
Interpretation: There was no evidence that regular use of inhaled salbutamol 400 microg four times daily for a year increased the exacerbation rate of asthma in the population studied.