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Severe bronchiolitis and childhood asthma: what’s the risk?

Published Online: August 11, 2016

Bronchiolitis is a common viral respiratory illness during infancy, leading to approximately 130,000 hospitalizations in the U.S. each year (i.e., severe bronchiolitis). While severe bronchiolitis is a known risk factor for childhood asthma, the probability of these infants developing asthma is not clear. To date, most studies of the association between severe bronchiolitis and asthma have been limited by small cohorts and conducted outside the U.S.

A study by Balekian and colleagues in The Journal of Allergy and Clinical Immunology: In Practice examined the risk of developing childhood asthma after severe bronchiolitis during infancy. The study was based on the Massachusetts General Hospital Obstetric Maternal Study (MOMS) cohort, which enrolled pregnant mothers receiving prenatal care at the Massachusetts General Hospital between 1998-2006. The investigators used data collected by the MOMS study, as well as longitudinal data collected from the electronic health records (EHR) of the mothers’ newly-born children. They collected information about admission to the hospital for severe bronchiolitis during infancy, as well as any diagnosis of asthma between ages 3 and 5 years. They collected demographic information including age, sex, race/ethnicity, as well as the presence of other related health conditions (such as atopic dermatitis, or heart and lung problems). They then assessed the risk of developing childhood asthma among children who had severe bronchiolitis during infancy, and compared this risk with that of children who did not experience severe bronchiolitis during infancy.

The study included 3,653 children who were born to women in the MOMS cohort. Overall, 2.9% of the children had severe bronchiolitis during infancy, which is comparable to prior studies. Of these children admitted to the hospital with severe bronchiolitis in the first year of life, 28% developed asthma by age 5 years. This risk of developing asthma was lower than in prior studies (40-50%), but still quite high. Severe bronchiolitis remained a significant risk factor for developing childhood asthma after adjusting for many other potential risk factors for childhood asthma.

Since asthma is one of the most common respiratory diseases of childhood, this study serves to reassure families and clinicians that most children who experience severe bronchiolitis are not destined to develop asthma. The reasons why almost 30% of the children developed asthma, while the other 70% did not, are the focus of ongoing studies. This research is not only of direct relevance for more than 100,000 children and their families each year, but it may provide valuable clues about asthma that apply to all U.S. children.

The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.