Lifetime stroke risk higher for women
Framingham Heart Study, Canadian Heart and Stroke Foundation - February 10, 2004

Women aged 55 and older have a one in five chance of suffering a stroke during their lifetime, while men the same age have a one in six chance, according to the latest data from an ongoing heart study.

‘This data estimates categories defined by age, sex and baseline blood pressure, and may identify risk factors that may motivate adults to adopt a healthier lifestyle,’ said Dr. Sudha Seshadri, assistant professor of neurology at the Boston University School of Medicine, and lead author of the Framingham Heart Study.

Researchers studied 4,883 participants from the original Framingham Heart Study who survived stroke-free to age 55. The participants were followed at two-year intervals for up to 40 years or until they had a first stroke, developed Alzheimer's disease or died. Data from a total of 114,300 person-years was collected.

Among the participants, 859 participants developed a stroke, 86 percent of which were ischemic (caused by blood clots that cut off blood supply to the brain).

Researchers calculated stroke risk at ages 55, 65, 75 and 85.

‘In women the lifetime stroke risk was 21 percent at age 55; while in men it was 17 percent at age 55. This risk was roughly the same at ages 65 and 75,’ she said. But risk declined slightly to 9 percent for men and 16 percent for women at age 85.’

The relationship between blood pressure and stroke risk was also striking: At every age the risk of stroke was higher for those who had higher blood pressure at age 55. ‘This is an important message that underlines the importance of lifetime control of blood pressure,’ she said.

‘People who had stage one hypertension, which is defined as a systolic blood pressure of 140 or higher or a diastolic blood pressure of 90 or higher had more than twice the risk for stroke than people who had normal blood pressure,’ she said.

Of note, the lifetime stroke risk was lowest for men and women whose blood pressure at age 55 was less than 120/80.

‘Blood pressure is known to be the single most important modifiable risk factor for stroke,’ Seshadri said. ‘Despite this knowledge, it is estimated that more than 65 percent of all hypertension remains either undetected or inadequately treated. This is the first time we have looked at the effect of blood pressure on the lifetime risk of stroke.'

According to the Canadian Heart and Stroke Foundation, stroke is the fourth leading cause of death in Canada. Each year, about 16,000 Canadians die from stroke, and more women than men die from stroke.

Findings from the Framingham Heart Study were presented this month at the American Stroke Association's 29th International Stroke Conference.