1250Grass pollen exposure and children’s asthma repeat admissions in Victoria, Australia

Abstract Background Paediatric asthma-related readmissions significantly challenge public health systems. As evidence suggests readmissions are possibly associated with ambient grass pollen levels, we sought to determine the relationship between grass pollen exposure and the risk of readmission for asthma among children in Victoria, Australia. Methods The Victorian Admitted Episodes Dataset 1st July 1997–30th June 2009 was used to identify primary admissions with a principal diagnosis of asthma for children aged 2-18 years. Total sample size was 48,068 admissions. Readmissions were defined as a subsequent admission within 28 days of index discharge. Multiple semi-parametric Poisson Generalized Additive Models were used to assess associations between the grass pollen season and daily grass pollen counts (lagged and cumulative) with repeat admissions, while controlling for meteorological factors and air pollutants. Results Readmissions totalled to 2,152 (4.47% of all admissions). Mean daily readmissions were 1.44 times higher during the grass pollen season (95%CI 1.03-2.02). Pollen season was associated with readmission only for the youngest age group (2-5), incident rate ratio 1.99 (95%CI 1.26-3.14). Daily readmission was non-linearly associated with same day pollen counts only for the 13-18-year age group. Lag 2 pollen counts were non-linearly associated with all daily readmissions for boys in gender-stratified and younger age groups (2-5, 6-12) in age-stratified analysis. Conclusions Grass pollen exposure was associated with higher readmission rates for paediatric asthma. Key messages Younger children and boys with severe or poorly controlled asthma need to be assessed for preventive therapies before the grass pollen season to reduce the repeat admissions.