NEW ORLEANS (Reuters Health) - The rapidly rising incidence of stroke among Americans is primarily due to the increasing number of middle-aged women who are having strokes. The increasing incidence is also associated with abdominal obesity, investigators told attendees here at the American Stroke Association's International Stroke Conference 2008.
"The incidence of stroke is two-times higher in women than men between the ages of 35 and 54," announced Dr. Amytis Towfighi of the University of Southern California, Los Angeles.
Towfighi and colleagues analyzed data from the National Health and Nutrition Surveys (NHANES) collected between 1988 and1994 that included 5,112 participants, as well as NHANES data collected between 1999 and 2004 that included 4,594 participants.
Towfighi said that women 35 to 54 years old who reported a history of stroke accounted for 1.79 percent of the 1999-2004 study population, but only 0.63 percent of women in the same age group in the 1988-1994 survey.
"The number of middle-aged women with stroke tripled," she pointed out.
The rate of traditional stroke risk factors, such as diabetes, cardiovascular disease and high blood pressure, didn't change between the two surveys, Towfighi added. "However, waist circumference and body mass index increased significantly."
Waist circumference and body mass index - the ratio of height to weight often used to determine whether an individual is over- or underweight -- also increased among men in the same age bracket, but not as sharply as in women.
She said that 47 percent of women in the earlier survey qualified as having abdominal obesity, with a waist circumference of 88 centimeters or greater, while 59 percent of women had abdominal obesity in the later survey. The proportion of men with abdominal obesity also increased from 29 percent to 41 percent.
"There is no good explanation for why abdominal obesity has a greater impact on stroke in women, except that it is one of the defining features of the metabolic syndrome, and the metabolic syndrome has a significantly greater effect on women than men," Towfighi told Reuters Health.
The metabolic syndrome refers to a cluster of cardiovascular risk factors including obesity, high blood pressure and diabetes type II.
Stroke may be one of those effects that women experience, she added.