This study aims to analyze whether bronchiolitis in children younger than one-year-old contributes to subsequent asthma. Medical data were retrieved from the National Health Insurance Research Database of Taiwan. Participants were divided into study (N = 65,559) and control (N = 49,656) groups, depending on whether they had early bronchiolitis. Incidences of asthma, potential comorbidities, and associated medical conditions were compared. The incidence of childhood asthma was significantly higher in the study group (aHR = 1.127, 95% CI: 1.063-1.195). Children with bronchiolitis hospitalization displayed higher asthma risk in the period between two and four years of age. The risk diminished as the children grew up. No relevant synergistic effects were found between bronchiolitis and atopic dermatitis. In conclusion, bronchiolitis before one year of age exhibits predictive value for development of preschool asthma, especially in children with bronchiolitis hospitalizations.
