Ambulance dispatches and heatwaves in Tasmania, Australia: A case-crossover analysis

Climate change is causing an increase in the frequency and severity of heatwave events, with a corresponding negative impact on human health. Health service utilisation during a heatwave is increased, with a greater risk of poor health outcomes identified for specific population groups. In this study, we examined the impact of heatwave events on ambulance dispatches in Tasmania, Australia from 2008 to 2019 to explore health service utilisation and identify the most vulnerable populations at a local level. Methods: We used a time-stratified case-crossover analysis with conditional logistic regression to examine the association between ambulance dispatches and three levels of heatwave events (extreme, severe, and low-intensity). We examined the relationship for the whole study population, and by age, gender, socio-economic advantage and clinical diagnostic group. Results: We found that ambulance dispatches increase by 34% (OR 1.34, 95% CI 1.18–1.52) during extreme heatwaves, by 10% (OR 1.10, 95% CI 1.05–1.15) during severe heatwaves and by 4% (OR 1.04, 95% CI 1.02–1.06) during low-intensity heatwaves. We found significant associations for the elderly (over 65), the young (5 and under) and for regions with the greatest socio-economic disadvantage. Conclusion: Heatwaves were associated with increased demands on ambulance services in Tasmania. In subgroups of people aged over 65 or under 5 years of age, and those from areas of higher disadvantage, we generally observed greater effect sizes than for the population as a whole. •Heatwaves have been linked to increases in ambulance dispatches in some regions of the world.•In Tasmania, heatwaves are associated with increased ambulance dispatches for the elderly, the young and those from areas of greater disadvantage.•Quantification of the impact on service demand enables ambulance services to prepare for staffing and surge capacity during heatwaves.•Characterisation of population groups at greater risk enables public health messaging and action to be tailored to those with the greatest need.•This study uses a novel attribution method of temperature by suburb, increasing accuracy of and confidence in results.