Hospital LOS is associated with rhinovirus etiology of bronchiolitis. Our data call attention to the importance of both RSV and rhinovirus testing in clinical research.

What is already known about this topic? Respiratory syncytial virus (RSV)-and rhinovirus (RV)-induced bronchiolitis are associated with an increased risk of asthma.What does this article add to our knowledge? Compared with children with RSV-induced bronchiolitis, children with RV-Ae or RV-Ceinduced bronchiolitis start asthma control medication earlier and are more likely to use it 4 years later. The risk is especially high among patients with RV-C, atopic dermatitis, and fever.How does this study impact current management guidelines? Secondary prevention strategies targeting rhinoviruses, especially RV-C, might help to prevent childhood asthma.BACKGROUND: Respiratory syncytial virus (RSV)-and rhinovirus (RV)-induced bronchiolitis are associated with an increased risk of asthma, but more detailed information is needed on virus types. OBJECTIVE: To study whether RSV or RV types are differentially associated with the future use of asthma control medication. METHODS: Over 2 consecutive winter seasons (2008-2010), we enrolled 408 children hospitalized for bronchiolitis at age less than 24 months into a prospective, 3-center, 4-year follow-up study in Finland. Virus detection was performed by real-time reverse transcription PCR from nasal wash samples. Four years later, we examined current use of asthma control medication. RESULTS: A total of 349 (86%) children completed the 4-year follow-up. At study entry, the median age was 7.5 months, and 42% had RSV, 29% RV, 2% both RSV and RV, and 27% non-RSV/-RV etiology. The children with RV-A (adjusted hazard ratio, 2.3; P [ .01), RV-C (adjusted hazard ratio, 3.5; P < .001), and non-RSV/-RV (adjusted hazard ratio, 2.0; P [ .004) bronchiolitis started the asthma control medication earlier than did children with RSV bronchiolitis. Four years later, 27% of patients used asthma control medication; both RV-A (adjusted odds ratio, 3.0; P [ .03) and RV-C (adjusted odds ratio, 3.7; P < .001) etiology were associated with the current use of asthma medication. The highest risk was found among patients with RV-C, atopic dermatitis, and fever (adjusted odds ratio, 5.0; P [ .03). CONCLUSIONS: Severe bronchiolitis caused by RV-A and RV-C was associated with earlier initiation and prolonged use of asthma control medication. The risk was especially high when bronchiolitis was associated with RV-C, atopic dermatitis, and fever. Ó

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.