Ratio of inhaled corticosteroid to bronchodilator treatment and asthma hospitalisation

Background: Previous research based on aggregated data has led to conflicting interpretations of the relationship between the corticosteroid:bronchodilator (C:B) ratio and outcome measures. Objectives: To assess whether the C:B ratio is associated with hospital contact for asthma at individual patient level. Methods: The study was a retrospective multivariate analysis, using data from the UK General Practice Research Database from 1993 to 1996. The subjects were 3465 asthma-diagnosed patients receiving bronchodilator and corticosteroid medication. The 'main outcome measures were asthma-related hospital contacts. Results: There was an inverse association between the C:B ratio and hospital contact after controlling for age. The odds ratio for the C:B ratio was 0.87(95% CI 0.73-0.98) and 1.04 (95% CI 1.01-1.07) for five-year agebands among patients aged five years ann over. There was no systematic relationship between the C:B ratio and hospital contacts for patients aged under five years. Conclusion: The results of this study shaw that higher C:B ratios are associated with lower levels of hospital contacts at patient level, although there are exceptions possibly linked to disease severity. For patients under five years, the ratio may not be a good outcome measure, perhaps owing to the difficulty in diagnosing asthma or poor compliance.