Obesity linked to increased risk of stroke: Study

According to a new study, obesity is a significant risk factor for stroke irrespective of race, gender and how it is measured.

Lead author of the study Dr Hiroshi Yatsuya, a visiting associate professor at the University of Minnesota, Minneapolis stated, “It has not been clear whether overweight and obesity are risk factors for stroke, especially among blacks.

“There are also questions about which measure of excess weight (body mass index - BMI, waist circumference or waist-to-hip ratio) is most closely associated with disease risk.”

Role of obesity in stroke rates across sex and race
In an effort to explore the potential contributions of obesity to stroke prevalence rates across sex and race, the researchers analyzed 13, 549 participants (5930 men and 7619 women; 3694 blacks and 9855 whites) with an average age of 53 years from four regions participating in the Atherosclerosis Risk in Communities (ARIC) study.

None of the subjects had any cancer or cardiovascular disease at the beginning of the study.

All the participants underwent three measures of obesity—body-mass index (BMI), waist circumference, and waist-to-hip ratio (WHR) and were tracked from 1987 to 2005.

Outcome of the study
During the follow-up period of 19 years, imaging studies and hospital records confirmed 598 ischemic strokes. The researchers noted that the results only varied slightly across race and sex and the elevated risk linked to weight was evident in every ethnic group.

“This was the first study that shows consistently that obesity increases the risk of stroke in both blacks and whites,” said Yatsuyu.

Obese black males were had nearly eight times higher incidence of stroke. White women were at the lowest risk and were 2.2 times as likely to have a stroke if obese.

The stroke rate in the lowest BMI category was 1.2 per 1,000 people for white women and 4.3 per 1,000 people for black women while that in the highest BMI category was 2.2 for white women and 8.0 for black men.

Yatsuyu stated, “Black women had about 3 times higher incidence of stroke than white women in the lowest as well as in the highest BMI categories. But the correlation between increasing stroke incidence and increasing degree of obesity was apparent in both races and genders.”

Obesity control vital for stroke prevention
The results of the study reveal that no matter which obesity measure was used, the risk of stroke was doubled among patients in the highest category compared with those in the lowest.

It reinforces the point that obesity causes ailments like hypertension and diabetes thereby elevating the risk factor for stroke.

Commenting on the study Dr Ralph L Sacco from the University of Miami, FL. said, “This [new] study is much larger and has much more statistical power and was able to show that BMI, as well as waist circumference and waist-to-hip ratio, all great markers for obesity, increased risk in both blacks and whites.”

The ARIC study was funded by the National Heart, Lung, and Blood Institute and was published online in Stroke: Journal of the American Heart Association.


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