Seventh of strokes blamed on smoking
Chinese study pins down tobacco risk
Reuters and Mary Ann Benitez – Updated on Mar 08, 2008
One in seven strokes among Chinese men are due to cigarette smoking, researchers in China and the United States found in a large-scale study that identified the habit as a major risk factor.
In an article published in Stroke: Journal of the American Heart Association, the researchers said prevention and kicking the smoking habit could reduce stroke deaths by almost 5 per cent on the mainland.
“Of the stroke risk factors that can be modified, cigarette smoking is probably second only to hypertension,” said Jiang He at Tulane University’s school of public health and tropical medicine, which led the study.
The study involved 83,533 men and 86,336 women over the age of 40 from 17 provinces. Nearly 60 per cent of the men and 13 per cent of the women were smokers at the start of the study in 1991.
The researchers tracked them over an average of 8.3 years, during which there were 6,780 strokes, 3,979 of them fatal.
After adjusting for factors such as age and blood pressure, smoking accounted for 14.2 per cent of strokes and 7.1 per cent of stroke fatalities in men, and 3.1 per cent of strokes and 2.4 per cent of stroke deaths in women.
Lam Tai-hing, head of the department of community medicine at the University of Hong Kong, said smoking was well established as a cause of stroke, but the significance of the study was that it was based on a large population sample.
“That is why their estimates of risk will be more precise than previous studies,” Professor Lam said.
A 2001 study by Professor Lam’s team estimated that the excess risk of death in Hong Kong smokers was from 58 to 120 per cent, depending on the number of cigarettes they smoked per day. In an average year, strokes occur in 0.19 per cent of the Hong Kong population aged 15 and over, according to the Department of Health.
“Smoking can kill by causing various fatal diseases such as strokes and heart diseases. People are advised not to start smoking,” a spokesman said.
Wong Tze-wai, of Chinese University’s department of community and family medicine, said smoking could lead to a narrowing of blood vessels in the brain, leading to strokes.
The chairman of the Hong Kong Council on Smoking and Health, Homer Tso Wei-kwok, said he hoped a smoke-free Beijing Olympics would be “the beginning of tobacco control policy for the mainland”.
“We have the largest smoking population in the world – 350 million. If we can just keep it at that number and not let it grow, that will be quite an achievement. Hong Kong is setting a good example [in tobacco control],” Dr Tso said.
The link between smoking and stroke was the strongest for ischemic stroke, which is caused when a blood clot blocks the circulation of blood to the brain.
Participants who smoked a pack or more per day were 51 per cent more likely to suffer an ischemic stroke.
Previous studies have shown that the Chinese are more prone to ischemic stroke than westerners.
