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Heat stroke, climate change and the elderly

The increased attention to this topic in Australia and North America reflects the increasing incidence of heat deaths and the need for public health and community measures to address the issue.

This article reviews some key references and reports and is intended as a topic for DEA members to talk about at meetings and for medical students to study. It will be an increasing part of medical practice in future.

Let us go straight to the symptoms, signs, what the elderly can do to protect themselves and what we can do for them. This is detailed very clearly by the Center for Disease Control and Prevention in the US and sets the clinical scene.

The key Australian report is “Protecting human health and safety during severe and extreme heat events

The report makes it clear that climate change is increasing the number of heat deaths but the problem has existed since settlement and is the natural disaster that kills most people. Deaths in cities are estimated to double by 2050.

Modelling based on the 2011 population, indicates an average of approximately 80 excess deaths associated with heat events each year across the major capital cities. Taking into account changes in population size and demographic composition, it is estimated that this annual average number of heat-related deaths will increase to between 120 and 130 in 2030, and to between 170 and 200 in 2050.  Deaths will be greatest in the southern capitals and Brisbane.

The impacts of heat are complex:-

“It is important to note that not all heat events are created equal. They exist on a continuum, varying in terms of their impact. At one end, the potential impacts include increased rates of morbidity, as well as a range of social and economic effects (e.g. increased rates of violent crime). As we move along the continuum, the possible impacts of heat events become more severe with the potential to cause unexpected deaths. At the very end of the continuum are those heat events that, while rare, can potentially have extreme impacts on morbidity, mortality and the broader social and economic fabric. The consequences of such events tend to be systemic and exacerbate each other (e.g. electricity load shedding triggered by an extreme heat event can limit the ability of individuals to stay cool using electrical appliances)”.

The report foreshadows and national framework for action

Research from the Harvard Medical School indicates that it is the variability of climate that is dangerous for the susceptible ie those with congestive failure, lung disease or diabetes.

In this study those years with larger summer temperature swings had higher death rates than those with smaller swings. This was true for each city examined in the US. Essentially people do not adapt as well to increased fluctuations around the usual temperature. This might be why the death rates are high in Melbourne. Indeed the 15,000 deaths in the heat wave in France in 2003 occurred in a population that had never experienced such temperatures before.

Please add other key references to this article

(1) Morbidity and mortality during heatwaves in metropolitan Adelaide