Women who smoke have a 25% higher risk of developing heart disease than male smokers do, according to a huge, new study.
Although the reason for the higher risk isn't known, researchers suspect there are biological differences in how women's bodies react to damaging cigarette smoke.
"Women may absorb more carcinogens and other toxic agents in cigarettes compared to men," said lead researcher Rachel R. Huxley, an associate professor of epidemiology at the University of Minnesota.
In addition, women have different smoking habits from men, she added. "Despite smoking fewer cigarettes than men on average, they may smoke more of the cigarette. They might smoke right to the end of the cigarette, compared to men - we just don't know," she said.
Smoking and heart disease
For the study, Huxley and her colleague, Mark Woodward from the department of epidemiology at Johns Hopkins University, gathered data from 75 studies, involving almost 4 million people, that looked at the risk of heart disease between smokers and nonsmokers.
This type of study is called a meta-analysis, the object of which is to pool data from a variety of sources to try to identify significant trends.
Combined, these studies included 3,912,809 people, more than 67,000 of whom had heart disease. In the 75 studies that included data on the differences between men and women and included 2.4 million people, the researchers found that women who smoked had a 25% higher risk of having a heart attack than men who smoked.
That risk increased by 2% for every year the women smoked, compared with men who smoked equally as long, Huxley and Woodward found.
Higher lung risk for women smokers
The risk to women could actually be greater than what was uncovered in this study, Huxley added. On average, women smoke fewer cigarettes than men and while the number of women who smoke has peaked in the United States, in developing countries women are just beginning to take up the habit, she said.
Huxley noted that they also found a higher risk for lung cancer among women who smoked, compared with men. "Women who smoked had twice the risk of dying from lung cancer, compared to men," she said.
"So this is not just a one-off thing," Huxley said. "There is some physiological or behavioural reason why women who smoke have a much greater risk of contracting illness, compared to their male counterparts," she said. The report was published in The Lancet.
What the research shows, Huxley added, is that anti-smoking campaigns need to be focused toward women as well as men. "Tobacco control programmes really need to have a female perspective; it can't be a generalised message, it has to be sex-specific," she said.
Dr Carolyn M. Dresler, director of the Tobacco Prevention and Cessation Program at the Arkansas Department of Health and coauthor of an accompanying journal editorial, agreed with that assessment.
Smoking a leading cause of death
"Women smoking in the world is a growth market for the tobacco industry," she said. Ways need to be found to "counter the very effective marketing of the tobacco industry," she added.
And she noted, "If we don't work to focus effective strategies for preventing and treating coronary heart disease in both sexes, we might improve only one of the sexes and leave the other behind."
Dr Gregg C. Fonarow, a cardiology professor at the University of California, Los Angeles and a spokesman for the American Heart Association, noted that "smoking remains the leading cause of preventable deaths in men and women worldwide."
It is very well-documented that smoking raises the risk of coronary heart disease in men and women, he added. "Complete cessation from smoking is by far the single biggest improvement to health that women and men who smoke can make," Fonarow said.
For more information on women and heart disease, visit the U.S. National Library of Medicine.
SOURCES: Rachel R. Huxley, Ph.D., associate professor of epidemiology, University of Minnesota, Minneapolis; Carolyn M. Dresler, M.D., director, Tobacco Prevention and Cessation Program, Arkansas Department of Health, Little Rock; Gregg C. Fonarow, M.D., professor, cardiology, University of California, Los Angeles, spokesman, American Heart Association; Aug. 10, 2011, The Lancet online .
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