[Lessons from Korean Childhood Asthma Study Cohort and Needs for Long-term Prospective Study].

Asthma has heterogeneous groups with various pathophysiological mechanisms, and the course and the prognosis of the disease may vary depending on the specific phenotype or endotype. However, to date, no study has comprehensively investigated the clinical characteristics and natural history of childhood asthma according to phenotype or endotype. To address this gap in knowledge, we established the Korean childhood asthma study (KAS), a nationwide pediatric asthma cohort consisting of 1,009 children with asthma recruited from 19 hospitals from 2016 to 2018. Cluster analysis of the KAS cohort identified four distinct clusters: (1) male-dominant atopic asthma, (2) early onset atopic asthma with atopic dermatitis, (3) puberty onset, female-dominant atopic asthma, and (4) early onset, less atopic asthma. Recently, we have attempted to overcome the problem of missing data during tracking periods by linking KAS cohort clinical data and Health Insurance Review and Assessment Service (HIRA) data. We also found 4 clusters based on the frequency of asthma exacerbations in children aged 0-12 and the degree of asthma medication use in children aged 6-12, suggesting that frequent exacerbations during early childhood can affect airway growth during childhood. To establish evidence-based national policies for whole life asthma prevention and management, a long-term prospective follow-up study focusing on the remission of childhood asthma and its transition to adulthood is needed.