Low incidence of respiratory syncytial virus hospitalisations in haemodynamically significant congenital heart disease

Background: Haemodynamically significant congenital heart disease (CHD) is a risk factor for severe respiratory syncytial virus (RSV) disease in young children. Population based data on the incidence of RSV hospitalisations in CHD patients are needed to estimate the potential usefulness of RSV immunoprophylaxis using palivizumab. Aims: ( 1) To obtain population based RSV hospitalisation rates in children,24 months of age with CHD. ( 2) To compare these rates with non-CHD patients and with previous studies. ( 3) To determine the number of patients needed to treat (NNT) with palivizumab to prevent one RSV hospitalisation. Methods: Six year, longitudinal, population based study at an institution, which is the sole provider of primary to tertiary in-patient care for a precisely defined paediatric population. Results: RSV hospitalisation rates ( per 100 child-years) in CHD patients aged <6, <12, 12 - 24, and <24 months of age were 2.5 (95% CI 0.8 to 5.6), 2.0 ( 0.8 to 3.8), 0.5 (0.1 to 1.8), and 1.3 (0.6 to 2.3), respectively, and the relative risk (RR) in comparison with non-CHD patients was 1.4 ( 0.6 to 3.1), 1.6 ( 0.8 to 3.2), 2.7 (0.7 to 9.7), and 1.8 (1.0 to 3.3), respectively. NNT was between 80 ( 35 to 245) and 259 ( 72 to 2140) for various age groups. Conclusion: RSV hospitalisation rates in CHD patients were fourfold lower than reported from the USA. Based on these low rates and RR, unrestricted use of palivizumab does not appear to be justified in this study area.