Relationships of bronchodilator response with asthma control and fractional exhaled nitric oxide in children with atopic asthma

ABSTRACT

PURPOSE: Because bronchodilator response (BDR) is variable among asthmatic patients, there are practical limitations in using BDR to assess asthma control. We investigated the relationships of BDR with asthma control status and fractional exhaled nitric oxide (FeNO) in children with atopic asthma. METHODS: One hundred ninety-one patients aged 8 to 16 years with atopic asthma were enrolled. Pulmonary function tests including BDR and FeNO were serially measured 10 times or more over 2 years when subjects were not receiving controller medications. During the last year of follow-up, the loss of asthma control was assessed in all participants. RESULTS: We identified 114 children (60%) with at least 1 positive BDR (> or =12%) over the 2-year observation period. Higher levels of BDRs and higher rates of positive BDRs were associated with lower lung function and lower methacholine PC20 (provocative concentration of methacholine causing a 20% fall in forced expiratory volume in one second). The loss of asthma control occurred in 106 of individuals (93%) who had positive BDRs, as compared to 52 of 77 (68%) with negative BDRs (P21 parts per billion than those who maintained asthma control (all P<0.001). CONCLUSION: Positive BDRs are linked to a higher probability of asthma control loss in children with atopic asthma. In addition, high FeNO is associated with asthma control loss in asthmatic children with negative BDRs.