Recurrent wheezing phenotypes after severe bronchiolitis and progression to asthma

BACKGROUND: Recurrent wheezing, a common diagnosis after severe bronchiolitis, has multiple phenotypes of uncertain relation to childhood asthma. OBJECTIVE: Among infants hospitalized for bronchiolitis, we investigated the relation of three 2020 recurrent wheezing phenotypes by age 4 years to asthma by age 6 years. METHODS: In a 17-center cohort study of infants hospitalized with bronchiolitis, we investigated the National Heart, Lung, and Blood Institute (NHLBI) 2020–defined recurrent wheezing phenotype and 2 additional phenotypes based on this definition: multitrigger and severe. As a sensitivity analysis, we examined the NHLBI 2007 recurrent wheezing phenotype. We calculated the proportion of study subjects who developed asthma by age 6 years and used multivariable logistic regression to examine characteristics associated with the highest-risk 2020 phenotype. RESULTS: Of 921 infants, 632 (69%) developed NHLBI 2020 recurrent wheezing, 734 (80%) developed multitrigger wheezing, and 165 (18%) developed severe wheezing by age 4 years; in addition, 296 (32%) developed NHLBI 2007–defined recurrent wheezing by age 3 years. Of 862 children with sufficient data (94%), 239 (28%) developed asthma by age 6 years. The proportions of children who progressed to asthma were as follows: 33% of those with NHLBI 2020–defined wheezing, 33% of those with multitrigger wheezing, 54% of those with severe wheezing, and 52% of those with NHLBI 2007–defined recurrent wheezing. The children with the severe phenotype who developed asthma had the associated characteristics preterm birth, child eczema, maternal asthma, and non–respiratory syncytial virus infection. CONCLUSION: Most infants with severe bronchiolitis developed the NHLBI 2020–defined recurrent wheezing phenotype by age 4 years. Depending on the phenotype, 33% to 54% will develop asthma by age 6 years. Future research will examine whether earlier treatment of high-risk phenotypes will improve wheezing symptoms and potentially prevent childhood asthma.