Predictors of Symptoms are Different from Predictors of Severe Exacerbations from Asthma in Children.
Chest. 2011 Feb 3. Wu AC, Tantisira K, Li L, Schuemann B, Weiss ST, Fuhlbrigge AL; for the Childhood Asthma Management Program Research Group. 1Center for Child Health Care Studies, Department of Population Medicine, Harvard Pilgrim Health Care Institute and Harvard Medical School, Boston, MA.
BACKGROUND: Asthma therapy is typically prescribed and titrated based on patient or parent self-report of symptoms. No longitudinal studies have assessed the relationship between symptoms and severe asthma exacerbations in children. The goal of our study was to (1) to assess the association of asthma symptoms with severe asthma exacerbations and (2) to compare predictors of persistent asthma symptoms and predictors of severe asthma exacerbations.
METHODS: The Childhood Asthma Management Program (CAMP) was a multi-center clinical trial of 1041 children randomized to receiving budesonide, nedocromil, or placebo (as-needed beta-agonist). We conducted a post-hoc analysis of diary cards that were completed by subjects on a daily basis to categorize subjects as having persistent versus intermittent symptoms. We defined a severe asthma exacerbation as an episode requiring three or more days of oral corticosteroids, hospitalization, or emergency department visit due to asthma based on self-report at study visits every four months.
RESULTS: While accounting for longitudinal measures, having persistent symptoms from asthma was significantly associated with having severe asthma exacerbations. Predictors of having persistent symptoms compared to intermittent symptoms included not being treated with inhaled corticosteroids, lower FEV(1)/FVC ratio, and a lower lnPC(20). Predictors of having one or more severe asthma exacerbations included younger age, history of hospitalization or emergency department visit in the prior year, three days or more of oral corticosteroids in the prior three months, lower FEV(1)/FVC ratio, lower lnPC(20,) and higher log10Eosinophil count; being treated with inhaled corticosteroids was predictive of having no severe asthma exacerbations.
CONCLUSIONS: Patients with persistent symptoms from asthma were more likely to experience severe asthma exacerbations. Nevertheless, demographic and laboratory predictors of having persistent symptoms are different from predictors of severe asthma exacerbations. Although symptoms and exacerbations are closely related, their predictors are different. The current national asthma guideline's focus on the two separate domains of asthma control, impairment and risk, are supported by our analysis.