Viral and Non-viral Episodes of Wheezing in Early Life and the Development of Asthma and Respiratory Phenotypes Among Urban Children

Background: Viral wheeze is an important risk factor for asthma, which comprises several respiratory phenotypes. We sought to understand if the etiology of early life wheezing illnesses relates to childhood respiratory and asthma phenotypes. Methods: Data were collected prospectively on 429 children in the Urban Environment and Childhood Asthma (URECA) birth cohort study through age 10 years. We identified wheezing illnesses and the corresponding viral etiology (PCR testing of nasal mucus) during the first three years of life. Six phenotypes of respiratory health were identified at 10 years of age based on trajectories of wheezing, allergic sensitization, and lung function. We compared etiology of early wheezing illnesses on these respiratory phenotypes and the development of asthma. Results: In the first three years of life, at least one virus was detected in 324 (67%) of the 483 wheezing episodes documented in the study cohort. Using hierarchical partitioning we found that non-viral wheezing episodes accounted for the greatest variance on asthma diagnosed at both 7 and 10 years of age (8.0% and 5.8% respectively). Rhinovirus wheezing illnesses explained the most variance on respiratory phenotype outcome followed by non-viral wheezing episodes (4.9% and 3.9% respectively) at 10 years of age. Conclusion and Relevance: Within this high-risk urban-residing cohort early life, non-viral wheezing episodes were frequently identified and associated with asthma development. Though rhinovirus wheezing illnesses had the greatest association with phenotype outcome, the specific etiology of wheezing episode in early life provided limited information about subsequent wheezing phenotypes.