Causal direction between respiratory syncytial virus bronchiolitis and asthma studied in monozygotic twins

This study compared long-term asthma, allergy, and pulmonary function outcomes in 37 pediatric monozygotic twin pairs who were discordant for hospitalization with verified RSV bronchiolitis in infancy. Endpoints of interest included lung function, bronchial responsiveness, FeNO, asthma diagnosis, asthma medication usage, and sensitivity to inhaled allergens. FEV1 in children aged ≥7 years was evaluated using a Vitalograph spirometer using Spirotrac software.