Usefulness of bronchodilator response as an index of asthma control in children

ABSTRACT

PURPOSE: Assessing asthma control is important for proper management, and various indices for objective assessment of asthma control, such as fractional exhaled nitric oxide (FeNO) and asthma control test (ACT) score have been proposed. Recently, bronchodilator response (BDR) was reported as a marker of poor asthma control in adults. This study aimed to assess the usefulness of BDR as a biomarker for childhood asthma. METHODS: A total of 305 children diagnosed with asthma were included. Spirometry with bronchodilator test was done at the time of diagnosis and about 14 months after asthma treatment. All children were evaluated by childhood asthma control test (c-ACT) and FeNO after asthma treatment. The patients were divided into 2 groups according to BDR results: the positive and negative BDR groups. Various biomarkers for asthma control, such as c-ACT, FeNO and changes of forced expiratory volume in 1 second (FEV1), were compared between the 2 groups. RESULTS: Of the 305 patients, 143 (46.9%) were positive and 162 (53.1%) were negative for BDR. The BDR-positive group showed lower FEV1. In the BDR positive group, FEV1 was significantly increased after asthma treatment, especially in children with airflow limitation which was defined as below 80% of FEV1 or atopy. In atopic children, BDR showed a significant negative correlation with c-ACT and a positive correlation with FeNO. CONCLUSION: In asthmatic children with airflow limitation at the time of diagnosis, BDR can be a useful index for predicting improvement in lung function by asthma maintenance treatment. BDR could be a reliable marker for the assessment of asthma control in atopic children.