Our aim was to evaluate the association between viral findings during bronchiolitis and the use of asthma controller medication (primary outcome) and systemic corticosteroids (secondary outcome) during the first post-bronchiolitis year.

We enrolled 408 children hospitalized for bronchiolitis at age <24 months in a prospective, 3-center, 1-year follow-up study in Finland. Viruses were detected with polymerase chain reaction in nasopharyngeal aspirates. The parents underwent a structured interview during hospitalization. Twelve months later, the use of asthma medication was asked in a structured questionnaire. Multivariable logistic regression was used for statistical analysis.

In total, 365 (89%) children completed the 1-year follow-up. The use of long-term asthma controller medication was highest in the rhinovirus-positive group (61% vs. 15% in RSV-positive group; adjusted OR 7.5, 95%CI 3.7-15.3), followed by children negative for both RSV and rhinovirus (36%; adjusted OR 2.6, 95%CI 1.3-5.3). Likewise, rhinovirus etiology was associated with more courses of systemic corticosteroids during the follow-up. The main findings were similar in a subset of infants aged <12 months with first wheezing.

Children hospitalized for rhinovirus-positive bronchiolitis used long-term asthma controller medication more often than those hospitalized for rhinovirus-negative bronchiolitis during first year after hospitalization.