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Impact of two recent extreme heat episodes on morbidity and mortality in Adelaide, South Australia: a case-series analysis.

Nitschke M, Tucker GR, Hansen AL, Williams S, Zhang Y, Bi P - Environ Health (2011)

Bottom Line: During the 2009 heatwave, direct heat-related admissions increased up to 14-fold compared to a three-fold increase seen during the 2008 event and during previous heatwaves.Only the 2009 heatwave was associated with considerable increases in total mortality that particularly affected the 15-64 year age group (1.37; 95% CI, 1.09, 1.71), while older age groups were unaffected.It is important that risk factors contributing to the adverse health outcomes are investigated to further improve preventive strategies.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Health, South Australia, 11 Hindmarsh Square Adelaide, South Australia 5000, Australia. monika.nitschke@health.sa.gov.au

ABSTRACT

Background: Extreme heatwaves occurred in Adelaide, South Australia, in the summers of 2008 and 2009. Both heatwaves were unique in terms of their duration (15 days and 13 days respectively), and the 2009 heatwave was also remarkable in its intensity with a maximum temperature reaching 45.7 °C. It is of interest to compare the health impacts of these two unprecedented heatwaves with those of previous heatwaves in Adelaide.

Methods: Using case-series analysis, daily morbidity and mortality rates during heatwaves (≥ 35 °C for three or more days) occurring in 2008 and 2009 and previous heatwaves occurring between 1993 and 2008 were compared with rates during all non-heatwave days (1 October to 31 March). Incidence rate ratios (IRRs) were established for ambulance call-outs, hospital admissions, emergency department presentations and mortality. Dose response effects of heatwave duration and intensity were examined.

Results: Ambulance call-outs during the extreme 2008 and 2009 events were increased by 10% and 16% respectively compared to 4.4% during previous heatwaves. Overall increases in hospital and emergency settings were marginal, except for emergency department presentations in 2008, but increases in specific health categories were observed. Renal morbidity in the elderly was increased during both heatwaves. During the 2009 heatwave, direct heat-related admissions increased up to 14-fold compared to a three-fold increase seen during the 2008 event and during previous heatwaves. In 2009, marked increases in ischaemic heart disease were seen in the 15-64 year age group. Only the 2009 heatwave was associated with considerable increases in total mortality that particularly affected the 15-64 year age group (1.37; 95% CI, 1.09, 1.71), while older age groups were unaffected. Significant dose-response relationships were observed for heatwave duration (ambulance, hospital and emergency setting) and intensity (ambulance and mortality).

Conclusions: While only incremental increases in morbidity and mortality above previous findings occurred in 2008, health impacts of the 2009 heatwave stand out. These findings send a signal that the intense and long 2009 heatwave may have exceeded the capacity of the population to cope. It is important that risk factors contributing to the adverse health outcomes are investigated to further improve preventive strategies.

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Duration and intensity of heatwaves in Adelaide. Distribution of daily maximum temperatures and number of days by heatwaves in Adelaide, 1993-2009.
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Figure 1: Duration and intensity of heatwaves in Adelaide. Distribution of daily maximum temperatures and number of days by heatwaves in Adelaide, 1993-2009.

Mentions: According to the definition, a total of 38 heatwave events occurred during the study period. The distribution of maximum temperature and duration during the Adelaide heatwaves is depicted in Figure 1. When excluding the two extreme events, the mean duration of heatwaves was 3.9 days with the longest duration of eight days occurring only twice. The 2008 event was the longest heatwave on record for any Australian capital city with 15 days over 35°C and a maximum daily temperature of 40.5°C. The average minimum temperature was 22.9°C and the highest minimum was 30.2°C. In comparison, the 2009 heatwave was more intense with the maximum temperature soaring to 45.7°C. The average minimum temperature was 26.1°C and the highest minimum was 33.9°C.


Impact of two recent extreme heat episodes on morbidity and mortality in Adelaide, South Australia: a case-series analysis.

Nitschke M, Tucker GR, Hansen AL, Williams S, Zhang Y, Bi P - Environ Health (2011)

Duration and intensity of heatwaves in Adelaide. Distribution of daily maximum temperatures and number of days by heatwaves in Adelaide, 1993-2009.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3116460&req=5

Figure 1: Duration and intensity of heatwaves in Adelaide. Distribution of daily maximum temperatures and number of days by heatwaves in Adelaide, 1993-2009.
Mentions: According to the definition, a total of 38 heatwave events occurred during the study period. The distribution of maximum temperature and duration during the Adelaide heatwaves is depicted in Figure 1. When excluding the two extreme events, the mean duration of heatwaves was 3.9 days with the longest duration of eight days occurring only twice. The 2008 event was the longest heatwave on record for any Australian capital city with 15 days over 35°C and a maximum daily temperature of 40.5°C. The average minimum temperature was 22.9°C and the highest minimum was 30.2°C. In comparison, the 2009 heatwave was more intense with the maximum temperature soaring to 45.7°C. The average minimum temperature was 26.1°C and the highest minimum was 33.9°C.

Bottom Line: During the 2009 heatwave, direct heat-related admissions increased up to 14-fold compared to a three-fold increase seen during the 2008 event and during previous heatwaves.Only the 2009 heatwave was associated with considerable increases in total mortality that particularly affected the 15-64 year age group (1.37; 95% CI, 1.09, 1.71), while older age groups were unaffected.It is important that risk factors contributing to the adverse health outcomes are investigated to further improve preventive strategies.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Health, South Australia, 11 Hindmarsh Square Adelaide, South Australia 5000, Australia. monika.nitschke@health.sa.gov.au

ABSTRACT

Background: Extreme heatwaves occurred in Adelaide, South Australia, in the summers of 2008 and 2009. Both heatwaves were unique in terms of their duration (15 days and 13 days respectively), and the 2009 heatwave was also remarkable in its intensity with a maximum temperature reaching 45.7 °C. It is of interest to compare the health impacts of these two unprecedented heatwaves with those of previous heatwaves in Adelaide.

Methods: Using case-series analysis, daily morbidity and mortality rates during heatwaves (≥ 35 °C for three or more days) occurring in 2008 and 2009 and previous heatwaves occurring between 1993 and 2008 were compared with rates during all non-heatwave days (1 October to 31 March). Incidence rate ratios (IRRs) were established for ambulance call-outs, hospital admissions, emergency department presentations and mortality. Dose response effects of heatwave duration and intensity were examined.

Results: Ambulance call-outs during the extreme 2008 and 2009 events were increased by 10% and 16% respectively compared to 4.4% during previous heatwaves. Overall increases in hospital and emergency settings were marginal, except for emergency department presentations in 2008, but increases in specific health categories were observed. Renal morbidity in the elderly was increased during both heatwaves. During the 2009 heatwave, direct heat-related admissions increased up to 14-fold compared to a three-fold increase seen during the 2008 event and during previous heatwaves. In 2009, marked increases in ischaemic heart disease were seen in the 15-64 year age group. Only the 2009 heatwave was associated with considerable increases in total mortality that particularly affected the 15-64 year age group (1.37; 95% CI, 1.09, 1.71), while older age groups were unaffected. Significant dose-response relationships were observed for heatwave duration (ambulance, hospital and emergency setting) and intensity (ambulance and mortality).

Conclusions: While only incremental increases in morbidity and mortality above previous findings occurred in 2008, health impacts of the 2009 heatwave stand out. These findings send a signal that the intense and long 2009 heatwave may have exceeded the capacity of the population to cope. It is important that risk factors contributing to the adverse health outcomes are investigated to further improve preventive strategies.

Show MeSH
Related in: MedlinePlus