Dose response of inhaled corticosteroids on bronchial hyperresponsiveness: a meta-analysis

Background: There is a relatively steep dose-response curve for effects of inhaled corticosteroids on conventional airway markers of asthmatic disease control. Objective: We sought to determine whether a dose-response effect exists for bronchial hyperresponsiveness. Methods: A meta-analysis of placebo-controlled trials in asthmatic patients was performed using a computerized systematic review of databases. Doubling dose/dilution protection of inhaled corticosteroid was compared with placebo. Studies which used direct (methacholine and histamine) and indirect (adenosine monophosphate) bronchial challenge stimuli were eligible for inclusion. Results: Twenty-five studies fulfilled eligibility criteria (963 patients). Values for doubling dose/dilution protection categorized by low/medium dose (< 1,000 mug) and high dose (greater than or equal to 1,000 mug) of inhaled corticosteroid amounted to a 1.25 (95% confidence interval 1.08 to 1.42) and 2.16 (95% confidence interval 1.88 to 2.44) shift, respectively. Conclusions: High doses of inhaled corticosteroids conferred greater improvements in bronchial hyperresponsiveness than low doses.