Heart Disease Risk Increases With Temperature Extremes

Michael Harper for redOrbit.com — Your Universe Online

The crazy weather we´ve been submitted to in recent years is more than a nuisance or even the subject of small talk down at the local coffee shop. According to new research today in Circulation: Cardiovascular Quality and Outcomes, an American Heart Association journal, the extreme temperatures, which often accompany unpredictable weather, can also increase the risk of premature cardiovascular disease (CVD) death.

To test this hypothesis, researchers traveled to Brisbane, Australia to analyze the association between the years of life lost as a result of CVD and the average daily temperature in the region. To determine the estimate of years of life lost, the team compared the age of death with the average life expectancy.

According to the study´s lead researcher and Ph.D. scholar, Cunrui Huang, M.Med., M.S.P.H., it is important to understand how these extreme temperature changes, a result of climate change, affect humans, especially those who are obese.

As the temperatures rise and fall dramatically, says Huang, so too does our blood pressure, blood thickness, cholesterol and even heart rate.

“With increasing rates of obesity and related conditions, including diabetes, more people will be vulnerable to extreme temperatures and that could increase the future disease burden of extreme temperatures,” said Huang.

Huang and his research team collected temperature data in Brisbane from 1996 to 2004, then compared this data to the number of CVD-related deaths which occurred during the same time frame.

The summers in Brisbane are normally hot and humid, while the winters remain largely dry and mild. Altogether, the average daily temperature in Brisbane between 1996 and 2004 came in at 68.9 degrees Fahrenheit, or 20.5 Celsius. Huang and team then characterized a cold snap and heat wave as the coldest and hottest 1% of all these days.

For every 1 million people, said Huang, 72 years of life were lost as a result of CVD.

Whenever the temperatures began to climb towards their upper peaks for 2 or more days, however, the risk of premature CVD death also rose.

“This might be because people become exhausted due to the sustained strain on their cardiovascular systems without relief, or health systems become overstretched and ambulances take longer to reach emergency cases,” said co-author of the study and professor of biostatistics at Queensland University of Technology, Dr. Adrian G. Barnett.

“We suspect that people take better protective actions during prolonged cold weather, which might be why we did not find as great a risk of CVD during cold spells.”

According to the American Heart Association, cold weather can be just as dangerous for your heart as warm weather.

When body temperature drops below 95 Fahrenheit, hypothermia sets in, meaning the body can´t create enough energy to keep itself warm. When this happens, the heart usually fails first, causing most hypothermia deaths.

In conclusion, Mr. Huang and Dr. Barnett suggest that, when the temperatures begin to spike or plummet, it´s best to remain indoors under temperate conditions. This way, the risk of premature CVD death is kept to a minimum.

The researchers are, however, willing to admit that the results of this study might be specific to the people of Brisbane, and might not have universal implications.

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