Sex May Affect Obesity-Blood Clot Link

Oct. 26, 2009 -- Obesity is a risk factor for blood clots in veins, and that may be especially true for men with big waists and women with big hips.

That's according to a new study of the condition, known as venous thromboembolism, published online in Circulation.

The study included more than 56,000 men and women in Denmark who were followed for about a decade.

When the study started, participants got their height, weight, waist, and hips measured. They also answered questions about their health and lifestyle factors.

During the study, the group had 641 cases of venous thromboembolism (VTE). VTE can be life-threatening if the blood clots travel to the lungs.

As expected, obesity was linked to a greater likelihood of developing a VTE. But where the weight gain occurred was key and affected men and women differently.

Obese men with big waists were particularly likely to develop VTEs. But for women, hip size mattered, not waist size. This relationship was independent of other risk factors, such as smoking, physical activity, height, hypertension, diabetes, cholesterol, and among women, the use of hormone replacement therapy.

"In women, hip circumference is more informative than waist circumference when predicting the risk of VTE ... whereas waist circumference is more informative than hip circumference in men," write the researchers, who included Marianne Tang Severinsen, MD, of Denmark's Aarhus University Hospital.

The reason for those patterns isn't clear from this study.