Efficacy of low and high dose inhaled corticosteroid in smokers versus non-smokers with mild asthma

Background: Cigarette smokers with asthma are insensitive to short term inhaled corticosteroid therapy, but efficacy when given for a longer duration at different doses is unknown. Methods: Ninety five individuals with mild asthma were recruited to a multicentre, randomised, double blind, parallel group study comparing inhaled beclomethasone in doses of 400 mu g or 2000 mg daily for 12 weeks in smokers and non- smokers. The primary end point was the change in morning peak expiratory flow ( PEF). Secondary end points included evening PEF, use of reliever inhaler, number of asthma exacerbations, spirometric parameters, and asthma control score. Results: After 12 weeks of inhaled beclomethasone there was a considerable difference between the morning PEF measurements of smokers and non- smokers with asthma ( 218 ( 95% CI 235 to 21), adjusted p = 0.035). Among those receiving 400 mg daily there was a difference between the mean ( 95% CI) morning PEF ( 1/ min) in smokers and non- smokers ( 225 ( 95% CI 245 to 24), adjusted p = 0.019) and in the number of asthma exacerbations ( 6 v 1 in smokers and non- smokers, respectively, p = 0.007). These differences were reduced between smokers and non- smokers receiving 2000 mu g inhaled beclomethasone daily. Conclusions: Compared with non- smokers, smokers with mild persistent asthma are insensitive to the therapeutic effect of low dose inhaled corticosteroid treatment administered for a 12 week period. The disparity of the response between smokers and non- smokers appears to be reduced with high dose inhaled corticosteroid. These findings have important implications for the management of individuals with mild asthma who smoke.