Study designs of evaluations included in the review
The inclusion criteria specified randomised placebo-controlled trials (RCTs) with either a placebo arm or placebo run-in period.
Specific interventions included in the review
The inclusion criteria specified interventions in which the doubling dose/dilution protection with inhaled corticosteroid was compared with a placebo. Interventions in which airway bronchoprotection was evaluated with either direct (methacholine and histamine) or indirect stimuli (adenosine monophosphate) were included. In all trials, BHR was tested after a steady state of at least 2 weeks was reached. All doses, delivery devices and type of inhaled corticosteroid were permissible.
Participants included in the review
The inclusion criteria specified asthmatic patients with BHR.
Outcomes assessed in the review
The inclusion criterion was the estimated doubling dose/dilution shift.
How were decisions on the relevance of primary studies made?
Two authors independently selected papers for the review from the lists of titles and abstracts. All authors then read the full papers to decide whether the studies should be included or excluded. Any discrepancies were resolved by discussion.