Longitudinal asthma exacerbation phenotypes in the Korean childhood asthma study cohort

Background Asthma exacerbation (AE) leads to social and economic costs and long‐term adverse outcomes. We aimed to predict exacerbation‐prone asthma (EPA) in children. Methods The Korean childhood Asthma Study (KAS) is a prospective nationwide pediatric asthma cohort of children aged 5–15 years followed every 6 months. Patients with AE during the 6 months prior to all three visits, with AE prior to one or two visits, and without AE prior to any visit were defined as having EPA, exacerbation‐intermittent asthma (EIA), and exacerbation‐resistant asthma (ERA), respectively. Risk factors and prediction models of EPA were explored. Results Of the 497 patients who completed three visits, 42%, 18%, and 15% had exacerbations prior to visits 1, 2, and 3 and 5%, 47%, and 48% had EPA, EIA, and ERA, respectively. Univariate and multivariable logistic regression revealed forced expiratory volume in 1 s (FEV1) z‐score, forced vital capacity (FVC) z‐score, white blood cell (WBC) count, and asthma control test (ACT) score as relevant EPA risk factors. The EPA prediction model comprised FVC z‐score, WBC count, ACT score, sex, and parental education level (area under the receiver operating characteristic curve [AUROC] 0.841 [95% confidence interval (CI): 0.728–0.954]). Conclusion With appropriate management, AE decreases over time, but persistent AEs may occur. Apart from asthma control level, baseline lung function and WBC count predicted EPA.