Inhaled steroids are associated with reduced lung function decline in subjects with asthma with elevated total IgE.
Résumé
BACKGROUND: Few studies have investigated the long-term association between inhaled corticosteroids (ICSs) and lung function decline in asthma. OBJECTIVE: To evaluate whether prolonged treatment with ICSs is associated with FEV(1) decline in adults with asthma. METHODS: An international cohort of 667 subjects with asthma (20-44 years old) was identified in the European Community Respiratory Health Survey (1991-1993) and followed up from 1999 to 2002. Spirometry was performed on both occasions. FEV(1) decline was analyzed according to age, sex, height, body mass index, total IgE, time of ICS use, and smoking, while adjusting for potential confounders. RESULTS: As ICS use increased, the decline in FEV(1) was lower (P trend = .025): on average, decline passed from 34 mL/y in nonusers (half of the sample) to 20 mL/y in subjects treated for 48 months or more (18%). When adjusting for all covariates, there was an interaction (P = .02) between ICS use and total IgE: in subjects with high (>100 kU/L) IgE, ICS use for 4 years or more was associated with a lower FEV(1) decline (23 mL/y; 95% CI, 8-38 compared with nonusers). This association was not seen in those with lower IgE. CONCLUSION: Although confirming a beneficial long-term association between ICSs and lung function in asthma, our study suggests that subjects with high IgE could maximally benefit from a prolonged ICS treatment. CLINICAL IMPLICATIONS: This study adds further evidence to the beneficial effect of inhaled steroids on lung function in asthma; future studies will clarify whether calibrating the corticosteroid dose according to the level of total IgE is a feasible approach in asthma management.