Feb. 6, 2004 (San Diego) — Cigarette smokers are four times more likely to develop subarachnoid hemorrhage (SAH) than are nonsmokers and the risk appears to be dose-dependent, according to results presented here today at the 29th International Stroke Conference.
The results of the study were also published in the online edition of Stroke, a journal of the American Heart Association.
SAH is more common in women and the link between smoking and SAH is strongest in women smokers, lead author Craig S. Anderson, PhD, FRACP, FAFPHM, professor in the Clinical Trials Research Unit at the University of Auckland in New Zealand, told Medscape.
Compared with persons who have never smoked, the odds ratio for SAH was 2.8 for those who smoke a pack or less a day and 5.2 for smokers who consume more than a pack a day.
Regardless of age, the SAH risk increases "as soon as a person starts smoking. But even though smoking is a very potent risk factor, as soon as one quits smoking the risk recedes very rapidly," he said. Within five years of quitting smoking SAH risk returns to roughly the same as the risk for nonsmokers. Thus, the risk "appears to be from acute rather than cumulative exposure," he said.
Dr. Anderson and colleagues studied medical records from 2.8 million residents (aged 15 years and older) of four cities in Australia and New Zealand from 1995 through 1998. They identified 432 cases of SAH and matched those to 473 healthy adults. In addition to demographic data on age, sex, income, and education, the researchers obtained information about smoking, exercise, alcohol consumption, history of heart disease, and presence of risk factors such as hypertension, diabetes, and family history of SAH.
Smokers were classified as current if they smoked cigarettes, cigars, or pipes at least once a day, with light smokers consuming less than a pack a day. People who lived with smokers were classified as passive smokers.
Of the 432 SAH cases, 62% were women in their mid-50s. Smoking history was available from 391 of the cases and 469 of the controls. Of the 165 current smokers who had SAH, 95 were women. "A third of the cases of SAH can be attributed to smoking," Dr. Anderson said.
He theorized that the inflammatory response to tobacco smoke may weaken endothelial structure. The weakened vessels are then at increased risk for rupture. "Sex hormones may also play a role in this process since SAH often occurs in women who are still producing sex hormones," Dr. Anderson said. The mean age for SAH was 49 years among smokers, 58 years among past smokers, and 62 years for people who never smoked.
29th International Stroke Conference: Abstract 63. Presented Feb. 6, 2004.
Reviewed by Gary D. Vogin, MD
Medscape Medical News © 2004 Medscape
Cite this: Peggy Peck. Smoking Linked to Increased Risk of Subarachnoid Hemorrhage - Medscape - Feb 06, 2004.
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