Background: Little is known regarding possible association between lung clearance index (LCI) monitoring the lung heterogeneity and asthma control and exacerbation. The aim of the study was to determine the relationship between LCI, level of asthma control, and the C-ACT (Childhood Asthma Control Test) score in asthma patients.
Method: This study included 97 patients who visited the outpatient department and admitted to the Department of Pediatrics, the CHA Bundang Medical Center, CHA University from October 2013 to December 2014 due to asthma control and exacerbation. The level of asthma control was classified according to the GINA guideline and asthma exacerbation was applied to asthma patients who were hospitalized. We measured the baseline IOS (Impulse oscillometry system), FeNO (Fractional exhaled nitric oxide), spirometry, and LCI, and evaluated the C-ACT score for each subject.
Results: Of the 97 subjects, the numbers of patients in the asthma control group, the partly controlled group, the uncontrolled group, and the asthma exacerbation group were 33, 23, 18 and 23, respectively. The mean age of each group was 7.64 ± 2.66 years; there was no statistical difference across the groups (P=0.733). The Spearman correlation coefficients revealed a significant correlation between C-ACT and LCI 2.5% (P=0.001) and Scond VT (P=0.003), but no significant correlation between C-ACT and FEV1 (r=0.136, P=0.08), FEV1/FVC (r=0.086, P=0.47), Rrs5 (r=0.000, P=0.998), Xrs5 (r=0.017, p=0.872) Z score, and FeNO (r=0.015, P=1.00). There were significant differences in LCI 2.5% (P<0.001), ScondVT (P<0.001), FEV1 (P<0.001), and FEV1/FVC (P=0.010), but no difference in Rrs5 (P=0.949) and Xrs5 (P=0.077) between the controlled group and the uncontrolled group.
Conclusion: LCI and Scond VT were closely correlated with the C-ACT score and were good parameters in differentiating the level of asthma control.