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

BACKGROUND: Asthma is an inflammatory disease of the airways, but in clinical practice inflammation is rarely monitored. The aim of this study was to assess the level of airway inflammation in steroid naïve adult and pediatric patients with intermittent asthma over one year. METHODS: 54 children and 50 adults with intermittent asthma (GINA step 1) were included. On up to 6 visits lung function, airway hyperresponsiveness to methacholine (PC(20)FEV(1)), sputum eosinophils and exhaled nitric oxide (FeNO) were assessed. RESULTS: 36 pediatric and 34 adult patients were able to produce at least three adequate sputum samples over the study period and were included into the analysis. In 8 children (22%) the percentage of sputum eosinophils was always below 2.5%. A higher level of eosinophils (>2.5%) was found on at least one visit in 16 (44%) and always >2.5% in 12 children (33%). In the adult group the respective numbers were 14 patients (41%) with always low (<2.5%), 17 (50%) with at least once over 2.5% and three patients (9%) were always above the threshold of 2.5% sputum eosinophils. CONCLUSION: These results demonstrate that a substantial number of children and adults with intermittent asthma under ß-agonist treatment only, have variable or persistently high levels of eosinophilic airway inflammation. Long-term studies are needed to observe the progression of asthma severity in such patient populations. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/1756-0500-7-925) contains supplementary material, which is available to authorized users.