This report provides an analysis of the health impacts of the January 2009 Victorian heatwave. This was a period during which Victoria experienced the most extreme temperatures, with many records set for high day and night-time temperatures, as well as for the duration of extreme heat.
Over the five days, 27–31 January 2009, maximum temperatures were 12–15°C above normal over much of Victoria. The temperature was above 43°C for three consecutive days from 28 to 30 January, reaching a peak of 45.1°C on 30 January 2009.
The January 2009 heatwave in Victoria was of unprecedented intensity and duration, with maximum temperatures 12–15°C above normal for much of Victoria, while Melbourne endured three consecutive days of temperatures above 43°C.
The population health impact of this extreme heat event has been assessed by collecting available data from five different sources: assessments by Ambulance Victoria (AV) metropolitan paramedics; locum doctor visits by the Melbourne Medical Deputising Service (MMDS); public hospital emergency department presentations as collected in the Victorian Emergency Minimum Dataset (VEMD); reportable deaths to the State Coroner’s Office (SCO); and death registrations collated by the Victorian Registry of Births, Deaths and Marriages (BDM).
Data for the week of the heatwave, 26 January to 1 February 2009, was compared with the same period in previous year(s). The results of this analysis have shown that there was substantial morbidity and mortality related to the heatwave, with associated demands on health services.
The following key findings were reported.
Ambulance Victoria metropolitan emergency caseload:
- a 25 per cent increase in total emergency cases and a 46 per cent increase over the three hottest days
- a 34-fold increase in cases with direct heat-related conditions (61 per cent in those aged 75 years or older)
- a 2.8-fold increase in cardiac arrest cases.
Locum GP attendances by MMDS:
- an almost fourfold increase in attendances for direct heat-related conditions (65 per cent in those aged 75 years or older)
- an almost twofold increase in calls to attend a deceased person.
Emergency department presentations:
- a 12 per cent overall increase in presentations, with a greater proportion of acutely ill patients and a 37 per cent increase in those aged 75 years or older
- an eightfold increase in direct heat-related presentations (46 per cent in those aged 75 years or older)
- an almost threefold increase in patients dead on arrival (69 per cent being 75 years or older).
Total all-cause mortality:
- There were 374 excess deaths over what would be expected – a 62 per cent increase in total all-cause mortality. The total number of deaths was 980 compared with a mean of 606 for the previous five years. The greatest number of deaths occurred in those aged 75 years or older, representing a 64 per cent increase.
- Included in these total deaths were 179 deaths reported to the SCO – a 77 per cent increase from the 101 deaths reported for the same period in 2008. Reportable deaths in those aged 65 years or older more than doubled.
Mortality during heatwaves can be difficult to measure, as deaths tend to occur from exacerbations of chronic medical conditions as well as direct heat-related illness, particularly in the frail and elderly.
Excess mortality provides a measure of impact but does not provide information specifically on the underlying cause of death.
This report provides a snapshot of a significant impact on mortality, morbidity and health service utilisation, with the greater burden of illness and death falling on the elderly. The insights gained will inform strategies already being developed to improve the resilience of Victorian communities to the impacts of extreme heat events.