Epidemiology, 2005; 16(5): S50.
This study investigates seasonal variation in paediatric hospitalisations and emergency room presentations for asthma and other (non-asthma) respiratory conditions. It also examines the association between these two conditions and climatic factors such as temperature and humidity. Back to Top | Article Outline Methods: Monthly hospital admissions (July 1992 to June 2003) and ER presentations (July 1998 to June 2003) for asthma and other (non-asthma) respiratory conditions in children younger than five years of age were aggregated in Canberra, Australia. We fitted log-linear models to describe these incidences in terms of calendar time, the current and previous month’s average temperature, and dew point average (a measure of humidity). A model with negative binomial errors was used to accommodate over-dispersion in the counts. The admissions and ER presentations of the previous month were also included in the models. Back to Top | Article Outline Results: Asthma comprised 2.7% of all child (<5 years) admissions and 3.6% of their ER presentations, while non-asthma respiratory conditions comprised 7.7% of child (<5 years) admissions and 17.7% of their ER presentations. Asthma admissions and ER presentations peaked in autumn; non-asthma respiratory conditions peaked in winter/spring and were lower in summer. There was a 250% increase between summer and winter in the number of non-asthma respiratory condition admissions and a 189% increase in ER presentations. There was only a 22% increase between summer and autumn in asthma admissions and a 25% increase in asthma ER presentations. An increase in temperature of the current month was significantly associated with a decrease in asthma admissions and ER presentations, and ER presentations for non-asthma respiratory conditions. An increase in the temperature of the previous month was significantly associated with a decrease in admissions for non-asthma respiratory conditions. Humidity was positively associated with increases in asthma admissions, and in ER presentations for both asthma and non-asthma respiratory conditions. These factors were significant after adjusting for season (which was also independently associated with non-asthma respiratory conditions, but not with asthma). This analysis will be extended to two other cities in Australia. Back to Top | Article Outline Conclusion: This study suggests that strategies to combat exacerbations of asthma and other (non-asthma) respiratory conditions should take into consideration climatic factors and seasonal effects on a population. The strength of the association of temperature and humidity with asthma and non-asthma respiratory conditions and a plausible biological pathway suggest that lower temperatures and higher humidity lead to higher asthma and respiratory hospital admissions and ER presentations. The association between other (non-asthma) respiratory conditions and high humidity may be related to asthma not being conclusively diagnosed in very young children when they present to the ER. Finally, understanding the influence of climatic factors on these conditions could assist hospital management with demand modeling and planning for services, especially staffing estimates and hospital beds. © 2005 Lippincott Williams & Wilkins, Inc.