Severe Respiratory Syncytial Virus Infection in Preterm Infants and Later Onset of Asthma.

Abstract

Respiratory syncytial virus (RSV) is the leading cause of viral lower respiratory tract infections in infants. Preterm infants are at increased risk for hospitalization with RSV (RSV-H), but there are few data on the relationship between RSV-H and asthma in preterm infants, or any data stratified by gestational age, and most studies have short follow-up periods. We sought to evaluate the relationship between serious RSV illness and onset of asthma up to 5 years of age in a cohort of preterm children and to quantify this association. A retrospective birth cohort of preterm infants (29 weeks 0 days to 35 weeks 6 days gestational age) was constructed from a provincial population-based database, and children were followed forward for 5 years. Incidence rates of RSV-H and asthma were determined. In a Cox proportional hazards model, controlled for putative confounding factors for asthma, the hazard ratio and 95% CI of asthma in children with and without RSV-H was evaluated. Among 3916 premature children, the incidence rate of RSV-H was 25/1000 infants. The cumulative incidence rate of asthma at 5 years of age in children with RSV-H was 57.9/1000 person-years compared with 36.7 in those without RSV-H; the adjusted hazards ratio for asthma in RSV-H infants was elevated at 1.58 (95% CI: 1.03-2.41). In prematurely born children, there is a moderate association between severe RSV infection, as measured by RSV-H in the first year of life, and asthma up to 5 years of age.