Epidemiological association of airway inflammation with asthma symptoms and airway hyperresponsiveness in childhood

The role of airway inflammation in childhood asthma is not well defined, despite modern treatment approaches recommending potent anti-inflammatory therapy for an increasing number of children. In this study, induced sputum analysis was used to investigate the relationships among sputum inflammatory cells (eosinophils and mast cells), asthma symptoms, and airway hyperresponsiveness to hypertonic saline in a cohort of 170 children aged 8-14 years. Children who reported asthma symptoms in the past 2 wk had a 2.25-fold (95% to CI, 1.20-4.24) increased odds of having significant sputum eosinophilia. Hyperresponsiveness to hypertonic saline was strongly associated with higher levels of sputum eosinophils ([OR] 4.36, 1.70-11.20), sputum mast cells (OR 7.46, 2.48-22.75), and nasal eosinophils (OR 4.73, 1.89-11.86). Interestingly, boys were more likely than girls to have features of airway inflammation (sputum mast cells, OR 3.33,1.15-9.65; nasal eosinophils, OR 3.25, 1.72-5.97), which is consistent with the known increase in asthma prevalence in boys in this age group. Airway inflammation with eosinophils and mast cells is likely to be important in the pathogenesis of asthma in childhood. Induced sputum analysis can be used to evaluate this problem and has the potential to be a useful tool for monitoring therapy.