Association of Age at First Severe Respiratory Syncytial Virus Disease With Subsequent Risk of Severe Asthma: A Population-Based Cohort Study.

ABSTRACT

OBJECTIVE: In a population-based cohort study, we determined the association between the age at first severe respiratory syncytial virus (RSV) disease and subsequent asthma. METHODS: Incidence rates and rate ratios of the first asthma-associated hospitalization after 2 years of age in children hospitalized for RSV disease at <3 months, 3 to <6 months, 6 to <12 months, and 12-24 months of age were calculated. RESULTS: The incidence of asthma-associated hospitalization per 1000 child-years among children hospitalized for RSV disease at <3 months of age was 0.5 (95% confidence interval [CI], .2-.7); at 3 to <6 months of age, 0.9 (95% CI,.5-1.3); at 6 to <12 months of age, 2.0 (95% CI, 1.4-2.7); and at 12-24 months of age, 1.7 (95% CI, 1.0-2.5). The rate ratio of hospitalization for asthma was 2-7-fold greater among children hospitalized for RSV disease at ages ≥6 months than that among those hospitalized for RSV disease at ages 0 to <6 months. CONCLUSIONS: Although the burden of RSV disease is highest in children aged <6 months, the burden of subsequent asthma is higher in children who develop RSV disease at ages ≥6 months.