Inhaled corticosteroid doses in asthma: an evidence-based approach.

OBJECTIVE To define the evidence for doses of inhaled corticosteroids in asthma and describe this in clinically meaningful, evidence-based terms. DATA SOURCE Cochrane Database of Systematic Reviews. STUDY SELECTION AND DATA EXTRACTION We identified systematic reviews of randomised controlled trials of dosing of inhaled corticosteroids in asthma. Data on efficacy and safety of different doses were extracted from meta-analyses and summarised as the number needed to treat (NNT) and number needed to harm (NNH). DATA SYNTHESIS Inhaled corticosteroids were highly efficacious, with a relatively flat dose-response curve. Three patients needed to be treated with fluticasone 100 microg daily to prevent worsening asthma (NNT 3), and for fluticasone 1000 microg the NNT was 2.1 patients. The dose-response curve for side effects was steep. For a dose of fluticasone 100 microg, oral candidiasis developed in one of every 90 subjects treated (NNH 90). In contrast, the NNH for fluticasone 1000 microg and 2000 microg daily were 23 and 6, respectively. CONCLUSION Level 1 evidence supports the use of low-dose inhaled corticosteroids in asthma. Clinicians should review doses of inhaled corticosteroids used for treating patients with asthma.