Characteristic features of airflow limitation and airway inflammation in stable school-aged asthmatics without requiring medication

Different phenotypes of airflow limitation and airway inflammation may be present in stable asthmatic adolescents without requiring any medication. We wanted to know the details of the airway function in these subjects. Thirty-four stable asthmatics (aged 8 - 18 years old) were studied by both airway reversibility test (ART), which compares flow volume curves before and after bronchodilator (BD) inhalation, and the fractional exhaled nitric oxide (FENO) level. They were free from asthmatic attacks for at least 12 months and without any medication for asthma for, at least, 3 months (range: 3-102 months) before examinations. As a control group, 51 age-matched and stable asthmatics currently receiving medication (aged 8 - 18 years old) were also examined. In both groups, the % predictive values of all lung function parameters were approximately 100% after BD. However, when dividing the subjects according to their responsiveness to BD, the number of high responders at both the central and peripheral airways were significantly higher in the group without medication than in the group with current medication (p<0.01). Furthermore, the % predictive value of FEV1.0 after BD in this subtype was significantly lower than the low responder subtype in the corresponding group (p<0.05). The FENO levels in subjects without medication were high (mean 63.9 ± 6.9 ppb), irrespective of the subtypes in ART. Regularly measuring lung function and controlling daily symptoms of asthma by anti-inflammatory agents may be helpful in inhibiting the progression of remodeling.