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Even in Warm Climates, Winter May Be Hazardous to Your Health

From the WebMD Archives

Oct. 11, 1999 (Atlanta) -- Balmy weather offers no real protection from death due to heart disease, according to a study in the Oct. 12 issue of Circulation: Journal of the American Heart Association. The findings add an interesting twist to prior theories on similar trends in northern, cooler areas.

The study, performed in southern California, shows that death due to heart disease is more likely to occur in December and January than in the remainder of the year, even in milder areas. Holiday-related overindulgence or stress may be to blame.

Previous studies in colder climates have found that there is an increase in rates of heart attacks and heart-related deaths during the winter. A prevailing theory was that the increase in incidents was explained by temperature-induced increases in blood clotting and blood pressure.

"The most important finding is that even in the mild climates, such as Los Angeles County, there are seasonal variations [in heart-related] death -- with 33% more deaths occurring in December and January than in June through September," lead author Robert A. Kloner, MD, PhD, tells WebMD. "We were surprised. ... I didn't think we'd see that much of a difference, but we did." Kloner is a professor of medicine at the University of Southern California. He is also the director of research in at The Heart Institute at the Good Samaritan Hospital in Los Angeles.

The researchers analyzed over 200,000 death certificates from 1985 through 1996 and found that there was an inverse relationship between the number of deaths and temperature. But during December and January, deaths rose around the holiday season and then fell; temperature alone did not explain this association. Over time, between 1985 and 1996, the number of monthly deaths fell.

Kloner says that, although cooler temperatures may play some role in the rise in death due to heart attacks in December and January, probably other factors contributed as well. The potential culprits, he says, may be holiday-related -- overindulgence (increased food, salt, and alcohol intake) and increased stress. High levels of particulate matter in the air due to wood burning in fireplaces may also be to blame, causing low oxygen levels in the blood which places stress on the heart. Other possibilities include changes in barometric pressure and respiratory infections.

So are there any preventive measures patients with heart disease can take during the winter? "I would avoid severe cold exposure," says Kloner. "Other things would be to reduce the known risk factors for coronary disease. Patients should stop smoking. If they have high cholesterol, high blood pressure, [or] diabetes, they should get that controlled. If they are overweight, they should lose weight." He also recommends that people with heart disease watch their holiday intake of food, salt, and alcohol.

"The good news is that there was about a 16% decrease in coronary deaths from 1985 to 1996," says Kloner. "This means we're making progress."

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