Purpose : The goal of asthma control is to maintain well-controlled state. In this study, we investigated whether childhood asthma control test (C-ACT) may reflect lung function and whether fractional exhaled nitric oxide (FeNO) can be used to improve the accuracy of C-ACT in reflecting the asthma control level.
Methods : We reviewed the medical records of 155 patients with asthma underwent lung function tests and C-ACT upon visiting our outpatient clinic. We compared lung function test results according to the C-ACT score stratified by atopy and also examined FeNO according to C-ACT and the Global Initiative for Asthma (GINA) guidelines. The diagnostic accuracy of well-controlled asthma by C-ACT, FeNO, and C-ACT+FeNO was examined. We also calculated the cutoff value of FeNO and C-ACT for well-controlled asthma.
Results : Peak expiratory flow (PEF) showed a significant correlation with the C-ACT score. Stratified by atopy, PEF, and forced expiration in one second (FEV1) showed significant correlations with the C-ACT score in the atopic asthma group. There was no difference in FeNO between subjects with C-ACT≥20 and <20, but FeNO was significantly higher in the uncontrolled asthma according to the GINA guidelines. The diagnostic accuracy of well-controlled asthma was higher when FeNO was combined with the C-ACT score than C-ACT or FeNO. Our study showed that the cutoff values of C-ACT and FeNO 19 and 18.3 ppb (parts per billion), respectively, for well-controlled asthma.
Conclusion : C-ACT showed a significant correlation with PEF, and atopic asthma group showed significant correlations with PEF and FEV1. A combination of C-ACT with FeNO might reflect asthma control status more accurately.