First treatment with inhaled corticosteroids and the prevention of admissions to hospital for asthma

Background-Early treatment with inhaled corticosteroids appears to improve clinical symptoms in asthma. Whether a first treatment initiated in the yea r following the recognition of asthma can prevent major outcomes such as ad mission to hospital has yet to be studied. Methods-A case-control study nested within a cohort of 13 563 newly treated asthmatic subjects selected from the databases of Saskatchewan Health (197 7-1993) was undertaken to investigate the effectiveness of a first treatmen t with inhaled corticosteroids in preventing admissions to hospital for ast hma. Study subjects were aged between five and 44 years at cohort entry. Fi rst time users of inhaled corticosteroids were compared with first time use rs of theophylline for a maximum of 12 months of treatment. The two treatme nts under study were further classified into initial and subsequent therapy to minimise selection bias and confounding by indication. Odds ratios asso ciated with hospital admissions for asthma were estimated using conditional logistic regression. Markers of asthma severity, as well as age and sex, w ere considered as potential confounders. Results-Three hundred and three patients admitted to hospital with asthma w ere identified and 2636 matched controls were selected. Subjects initially treated with regular inhaled corticosteroids were 40% less likely to be adm itted to hospital for asthma than regular users of theophylline (odds ratio 0.6; 95% CI 0.4 to 1.0). The odds ratio decreased to 0.2 (95% CI 0.1 to 0. 5) when inhaled corticosteroids and theophylline were given subsequently. Conclusion-The first regular treatment with inhaled corticosteroids initiat ed in the year following the recognition of asthma can reduce the risk of a dmission to hospital for asthma by up to 80% compared with regular treatmen t with theophylline. This is probably due, at least in part, to reducing th e likelihood of a worsening in the severity of asthma.