Inhaled corticosteroids compared to placebo for prevention of exercise induced bronchoconstriction.

BACKGROUND

The pathogenesis of exercise induced bronchoconstriction is likely multifactorial and is not completely understood. Inflammation plays an important role in the pathogenesis of exercise induced bronchoconstriction in asthmatic subjects but the evidence seems less strong in non-asthmatic subjects. The management of exercise induced bronchoconstriction focuses on prevention, through both pharmacologic and non-pharmacologic interventions.

OBJECTIVES

The objectives of this review were to evaluate the use of inhaled corticosteroids in the treatment of exercise induced bronchoconstriction in a systematic way. Specifically, the review was designed to: determine whether inhaled corticosteroids (compared to placebo) has an attenuating effect on exercise induced bronchoconstriction in adult and pediatric asthmatic patients; estimate the magnitude of the attenuating effect.

SEARCH STRATEGY

We searched the Cochrane Airways Review Group Specialised Register of trials, the Cochrane Central Register of Controlled Trials, review articles, textbooks and reference list of articles.

SELECTION CRITERIA

Randomised trials in adults or children comparing inhaled corticosteroids with placebo to prevent bronchoconstriction in patients with exercise induced bronchoconstriction.

DATA COLLECTION AND ANALYSIS

Trial quality assessment and data extraction were conducted independently by two reviewers.

MAIN RESULTS

The results from six randomised controlled trials involving 123 participants were analyzed (two trials involving adults and four involving children). Combining results from the two parallel studies with at least 4 weeks duration of inhaled corticosteroids, the use of inhaled corticosteroids significantly attenuated the percent fall index in forced expiratory volume in 1 second (WMD = 14.07%; 95% CI: 11.62% to 16.52%). The result from one crossover study with duration of inhaled corticosteroids of 4 weeks revealed significant attenuation of percent fall in forced expiratory volume in 1 second ( WMD = 6.90%; 95% CI: 1.40% to 12.40%) and the percent fall in peak expiratory flow ( WMD =11.50%; 95% CI: 6.31% to 16.69%). The small amount of data from placebo-controlled trials using a single treatment do not currently allow conclusions to be drawn.

AUTHORS' CONCLUSIONS

Inhaled corticosteroids used for 4 weeks or more before exercise testing significantly attenuated exercise-induced bronchoconstriction. The relative benefits of inhaled corticosteroids compared to other forms of exercise induced bronchoconstriction treatment (sodium cromoglycate, nedocromil sodium, salbutamol, and other anti-inflammatory agents) remains unclear.