RSV increases the risk of first paediatric asthma hospitalisation: whole-of-population cohort study

Backgroud: There is ongoing debate on the contribution of respiratory syncytial virus (RSV) disease to subsequent development of childhood asthma. We determined the risk of first asthma hospitalisation in children who developed severe RSV disease. Method: We performed a retrospective cohort analysis using population-based linked data for all children born in New South Wales, Australia between 2000-2010. The exposure was any RSV associated respiratory hospitalisation before the age of 2 years in the cohort child; the outcome was first episode of asthma hospitalisation after the age of 2 until the end of follow-up period. To account for non-proportional hazard of first asthma hospitalization, we used a time dependant Cox model to determine hazard ratio (HR) for first asthma hospitalisation in children who had RSV hospitalisation in the first 2 years of life compared to those who did not. Results: The cohort comprised 847,516 children. In total 22,379 (3%) cohort children had 36,560 episodes of asthma hospitalisations between ages 2-11 years. The adjusted HR for first asthma hospitalisation in children who had a RSV hospitalisation compared to those who did not, at age 24-30 months was 4.5 (95% CI 4.2-4.8), at 31-36 months was 3.4 (95% CI 3.2-3.7), at 37-49 months was 3.0 (95% CI 3.2-2.8), 2.6 (95% CI 2.4-2.7) beyond 4 years and persisted till 7 years of age. Conclusion: This large population-based study demostrates an increased risk of first asthma hospitalisation which persisted upto 7 years of life in children who had severe RSV disease in the first 2 years of life . An effective RSV vaccine in infancy may have a significant impact on paediatric asthma hospitalisations.