Risk factors associated with RSV hospitalisation in the first 2 years of life, among different subgroups of children in NSW: a whole-of-population-based cohort study.

Background Data on risk factors for respiratory syncytial virus (RSV)-associated hospitalisation in Australian children may be informative for preventive measures. Methods A whole-of-population-based study was conducted to identify comparable risk factors for RSV hospitalisation in different subgroups of children aged <2years in New South Wales. The cohort was divided into Indigenous children and high-risk and standard risk non-Indigenous children. Data on risk factors were obtained from the Perinatal Data Collection. RSV hospitalisations were ascertained from the Admitted Patient Data Collection. Adjusted HRs were calculated for each subgroup. Population-attributable risk associated with risk factors was estimated. Results Four factors were associated with increased risk of RSV hospitalisation: maternal smoking during pregnancy, male sex, multiparity and birth during the first half of the RSV season. Increase in relative socioeconomic advantage was associated with decreased risk of hospitalisation. Among high and standard risk non-Indigenous children, the hazard was approximately double for children born to multiparous women compared to those born to primiparous women and among Indigenous children the hazard was approximately double among those born during the first half of the RSV season. Maternal smoking during pregnancy was associated with a 26-45% increased risk across subgroups and accounted for 17% (95% CI 9.3% to 24%) of RSV hospitalisations in Indigenous children, 5% (95% CI 2.5% to 8%) in high-risk and 6% (95% 5% to 7%) in standard risk non-Indigenous children. Discussion Promoting avoidance of smoking during pregnancy may help in lowering the disease burden, with Indigenous children likely to benefit most.