Effect of inhaled corticosteroids on bronchial responsiveness in patients with "corticosteroid naive" mild asthma: a meta-analysis

Background-Inhaled corticosteroids are the most efficacious anti-inflammato ry drugs in asthma. International guidelines also advocate the early introd uction of inhaled corticosteroids in corticosteroid naive patients. A study was undertaken to assess the effects of inhaled corticosteroids on bronchi al hyperresponsiveness in patients with corticosteroid naive asthma by conv entional meta-analysis. Methods-A Medline search of papers published between January 1966 and June 1998 was performed and 11 papers were selected in which the patients had no history of treatment with inhaled or oral corticosteroids. Bronchial respo nsiveness to bronchoconstricting agents was considered as the main outcome parameter. Doubling doses (DD) df histamine or methacholine were calculated . Results-The total effect size of inhaled corticosteroids (average daily dos e 1000 mu g) versus placebo in the 11 studies was +1.16 DD (95% confidence interval (CI) +0.76 to +1.57). When only the eight short term studies (2-8 weeks) were analysed the effect size of the bronchoconstricting agent was 0.91 DD (95% CI +0.65 to +1.16). No relationship was found between the dose of inhaled corticosteroid used and the effect on bronchial responsiveness. Conclusion-This meta-analysis in patients with corticosteroid naive asthma indicates that, on average, high doses of inhaled corticosteroids decrease bronchial hyperresponsiveness in 2-8 weeks. It remains unclear whether ther e is a dose-response relationship between inhaled corticosteroids and effec t on bronchial hyperresponsiveness.