Risk factors for asthma after infant bronchiolitis

Five studies carried out after bronchiolitis at less than 24 months of age, with a follow-up of more than 10 years, reported that atopic dermatitis, family asthma, early-life exposure to tobacco smoke and rhinovirus aetiology were early-life risk factors for later asthma. This study evaluated the long-term outcome at 11-13 years of age of children who were hospitalized for bronchiolitis in early infancy.

We previously prospectively followed 166 children hospitalized for bronchiolitis at less than 6 months of age until 5-7 years of age. The current study included a structured questionnaire, parental interviews, clinical examinations and bronchodilation test of 138 of those children at 11-13 years of age.

Respiratory syncytial virus caused 66% of the bronchiolitis cases, and nearly half of the patients were exposed to tobacco smoke in early life. Doctor-diagnosed asthma was present in 13% of the former bronchiolitis patients at 11-13 years of age. Maternal asthma was the only independently significant risk factor in early life (adjusted OR 3.45, 95% CI 1.07-11.74), as was allergic rhinitis at 5-7 years of age (adjusted OR 4.06, 95% CI 1.35-12.25).

After bronchiolitis at less than 6 months of age, the risk of doctor-diagnosed asthma at 11-13 years was about twice that of the general Finnish population. Maternal asthma was the only independently significant early-life risk factor for current asthma at 11-13 years of age.