Statistical and spatial analysis of ambulance callouts during heat waves: A health indicator of climate change?

Abstract

Introduction: Climate change will exacerbate existing health problems in people vulnerable to present day climatic conditions. Indicators to measure and track the impact of climate change on health and identify areas for intervention have not been developed in Australia. Data for use as indicators need to be readily available, reliable and able to show trends over long periods of time. Ambulance callout data are routinely available and the frequency and spatial distribution of callouts may be associated with climate variables and vulnerabilities. The aim of this paper was to assess ambulance callouts as a health indicator by association with heat waves. Methods: Ambulance callouts in metropolitan Adelaide, South Australia were examined for the period 1994-2014. Incidence rate ratios (IRR) in heatwave periods were compared with non-heat wave periods, and mapped using geospatial techniques to identify heat-susceptible suburbs. Results: IRRs were not uniform across suburbs. Spatial distributions were compared to a vulnerability map based on risk factors such as older age, living alone and low socioeconomic status. The relative risk of ambulance callouts during heatwaves was greatest in some disadvantaged suburbs. Conclusions: The results suggest that ambulance callouts can be used as health indicator of climate change, and are also associated with vulnerable populations. Spatial data can help to target mitigation and adaptation interventions. In addition, the effectiveness of both policy-level and community-level interventions can be monitored.