Objective: The Childhood Asthma Control Test (C-ACT), a seven-item, self-administered questionnaire, has been used as a tool to assess the control level in children with asthma. The aim of this study was to determine whether the C-ACT reflects airflow limitation and airway inflammation in addition to clinical manifestations.
Methods: Asthmatic children aged 5-11 years who were able to perform the lung function test and fractional exhaled nitric oxide (FeNO) evaluation correctly were recruited during their regular visits. Children and their parents were asked to answer the officially developed Japanese version of the C-ACT.
Results: Among 258 children (176 boys, median age 9 years), there was a significant positive correlation between the C-ACT score and the percent predicted forced expiratory volume in 1 s (%FEV(1)) (r = 0.317, p < .001). The accuracy of the C-ACT for identifying asthmatic subjects with normal lung function (%FEV(1) >80%) described as the area under the receiver operating characteristic curve was 71.5% (95% CI = 62.8-80.2%, p < .001), and based on the Youden index the optimal cutoff score was 23 (sensitivity of 78% and specificity of 54%). In contrast, there was no relationship between the C-ACT score and the FeNO value.
Conclusions: These results suggest that a cutoff score of 23 for the C-ACT could be useful for identifying children with well-controlled asthma and normal lung function. Further studies are warranted to develop an easy-to-use questionnaire to assess the extent of airway inflammation in children.