Predictors of poor response during asthma therapy differ with definition of outcome

Abstract

Aims: To evaluate phenotypic and genetic variables associated with a poor long-term response to inhaled corticosteroid therapy for asthma, based independently on lung function changes or asthma exacerbations. Materials & methods: We tested 17 phenotypic variables and polymorphisms in FCER2 and CRHR1 in 311 children (aged 5–12 years) randomized to a 4-year course of inhaled corticosteroid during the Childhood Asthma Management Program (CAMP). Results: Predictors of recurrent asthma exacerbations are distinct from predictors of poor lung function response. A history of prior asthma exacerbations, younger age and a higher IgE level (p < 0.05) are associated with recurrent exacerbations. By contrast, lower bronchodilator response to albuterol and the minor alleles of RS242941 in CRHR1 and T2206C in FCER2 (p < 0.05) are associated with poor lung function response. Poor lung function response does not increase the risk of exacerbations and vice versa (p = 0.72). Conclusion: Genetic and phenotypic predictors of a poor long-term response to inhaled corticosteroids differ markedly depending on definition of outcome (based on exacerbations vs lung function). These findings are important in comparing outcomes of clinical trials and in designing future pharmacogenetic studies.