Smoking increases bleeding strokes among women

American Heart Association
Thursday, 13 November 2003

Smoking increases a woman's risk of having an intracerebral hemorrhage, a severe and often fatal stroke, according to a study published in today's rapid access issue of Stroke: Journal of the American Heart Association.

Scientists have known that in women, smoking increases the risk of ischemic strokes – those caused by blood clots blocking the blood supply – and subarachnoid hemorrhage, caused by the rupture of a blood vessel on the brain's surface bleeding into the area around the brain.

They haven't known, however, whether smoking increased women's risk of intracerebral hemorrhage, said the study's lead author Tobias Kurth, M.D., Sc.D., instructor of medicine at Brigham and Women's Hospital, Harvard Medical School in Boston. An intracerebral hemorrhage occurs when an artery inside the brain bursts, flooding the surrounding tissue with blood. Intracerebral hemorrhage is more common than subarachnoid hemorrhage.

In a study published earlier this year, Kurth and colleagues found that intracerebral hemorrhage is a risk for male smokers.

In the latest study, Kurth and colleagues used data from the Women's Health Study, an examination of 39,783 U.S. women who reported their smoking habits and were followed by researchers for nine years for stroke occurrence. The researchers categorized the women as never smokers, past smokers, current smokers of less than 15 cigarettes a day and current smokers of 15 or more cigarettes a day.

There were 70 hemorrhagic strokes during the study period, and 40 were intracerebral hemorrhages. The researchers found that compared to never-smokers, women who smoked 15 cigarettes or more a day had a 3.3-fold increase in the risk of all types of bleeding, or hemorrhagic, strokes; a 2.7-fold increase of intracerebral hemorrhage; and a 4-fold increase of the subarachnoid bleeding.

The results of this study are similar to the results of Kurth's study of intracerebral hemorrhage in male smokers.

Kurth and colleagues found that people who said they were past smokers did not have increased risk of hemorrhagic stroke. "We interpret this finding as a suggestion that stopping smoking might be a preventive factor for hemorrhagic stroke, although we cannot give an exact timeframe of how long you have to stop smoking," he said.

The study adds to the scientific evidence that smoking is a risk factor among men and women for all stroke subtypes, Kurth said. "The problem with the occurrence of a hemorrhagic stroke is that it can be severe and sometimes very disabling. Anything that prevents that severe outcome is certainly helping not only people individually, but also cutting down healthcare costs and long-term disability."

Co-authors are Carlos S. Kase, M.D.; Kaus Berger, M.D., M.P.H., M.Sc.; J. Michael Gaziano, M.D., M.P.H.; Nancy R. Cook, Sc.D. and Julie E. Buring, Sc.D.

The National Institutes of Health funded the study.

For more information, or to contact American Heart Association, see their website at: www.americanheart.org