Longitudinal measurement of airway inflammation over one year in children and adults with intermittent asthma

RATIONAL: Asthma is an inflammatory disease of the airways. In clinical practice, however, airway inflammation is rarely measured to monitor the patient and to adjust medication. The aim of this study was to assess the level of airway inflammation in adult and pediatric patients with steroid naive, intermittent asthma over one year and to determine the proportion of patients with persistently increased levels of sputum eosinophils. METHODS: 36 pediatric and 34 adult patients with intermittent asthma (GINA step 1) were included into the analysis. On up to 6 visits over one year lung function, airway hyperresponsiveness to methacholine (PC20FEV1), sputum eosinophils and fractional exhaled nitric oxide (FeNO) were assessed. These patients were under standard supervision of their pneumologist, who were blinded to the results obtained in this study and treated them based on symtoms and lung function according to recent GINA guidelines. RESULTS: 53% of the children had a median percentage of sputum eosinophils >2.5%. These children had lower airway hyperresponsiveness (median (IQR) 4.0 (5.9) vs. 0.7 (1.5), p<0.01), but did not differ with respect to FeNO or lung function from to the children with normal sputum composition. 29% of the adults had >2.5% sputum eosinophils. These adults had a comparable lung function, but, showed a significantly lower PC20FEV1 (0.4 (0.7) vs. 2.1 (7.0), p=0.01) and higher FeNO concentrations (81.4 ± 100.8 ppb vs.28.9 ± 20.8 ppb, p<0.05) compared to adults with normal sputum composition. CONCLUSION: A substantial number of children and adults with intermittent asthma under ß-agonist treatment have persistently high levels of airway inflammation. As continued airway inflammation may lead to airway remodeling, anti-inflammatory treatment even for patients in the mild stage of the disease should be considered.