Actual use of inhaled corticosteroids and risk of hospitalisation: a case-control study
Background: The relationship between therapy and adverse outcome in asthma is debated especially for naturally occurring situations. This is due in part to insufficient information regarding actual use of medications. Objective: This study was conducted to clarify the relationship between actual intake of anti-asthma drugs and asthma hospitalisation, considered as an outcome. Methods: A case-control study was performed. Patients hospitalised for an asthma exacerbation were matched to community controls identified in surrounding general practices. Patients were questioned to identify prior use of anti-asthma medications, level of use of inhaled corticosteroids and attitude towards therapy. Results: Twenty-three cases and 31 matched controls were interviewed. Cases tended to have more severe asthma than controls, as judged by more frequent use of oral corticosteroids. Cases tended to make more frequent use of oral xanthines and inhaled anticholinergics, but the proportion of patients using inhaled β2-adrenoceptor agonists and inhaled corticosteroids was similar in both groups. Use of lower doses of inhaled corticosteroids was associated with an increased risk of hospitalisation, while higher dosage was associated with␣decreased risk. Cases and controls differed as to their answers to a questionnaire concerning attitudes: cases expressed less interest in optimal usage of inhaled␣corticosteroids than controls; they also expressed more confidence in inhaled β2-agonists. When both risks were combined, overconfidence in β2-agonists and suboptimal use of inhaled steroids, the relationship with hospitalisation was significant (OR 5.5, 95% CI 1.1; 26.1). Conclusion: The results suggest that patients' attitudes to inhaled corticosteroids and actual consumption of these medications are directly related to adverse outcome in asthma.