The relationship of airway inflammation with asthma severity remains unclear. Our aim was to correlate the results of recommended methods of assessment of inflammation with measures of asthma control, in children with a wide range of asthma severity. The study was a cross-sectional investigation of 58 children receiving a wide range of treatment, including 10 treated without regular maintenance therapy and 29 treated with high-dose inhaled corticosteroids (CS). Exhaled nitric oxide (NO), serum eosinophil cationic protein (ECP), and induced sputum (processed for eosinophil count and ECP level) were related to recent symptoms, lung function, and bronchial responsiveness. There was no significant correlation between the results of any
Method: Neither did any marker of airway inflammation relate to recent symptoms, unlike PC20, which did. There was a significant, inverse correlation between the forced expiratory volume in 1 s (FEV1) and both NO and sputum ECP (r=-0.46, p=<0.001; r=-0.48, p=0.004, respectively). Sputum eosinophils were inversely related to the dose of methacholine that corresponded to a 20% fall in FEV1 (PC20) (r=-0.57, p=0.02). Serum ECP did not relate to any measure of asthma control. There was no association of any recommended inflammation markers with current symptoms and only a weak relationship between them and physiological measures. The place of these markers remains unclear and their use in clinical practice needs further investigation by long-term longitudinal studies.