May 8, 2010

Taller Men Have Higher Risk Of Blood Clots

A new study suggests that men who are over six feet tall have a higher risk of blood clots than shorter men do, while height seems to have no impact on risk to women.

The blood clots, known as venous thromboembolisms, include deep vein clots -- that usually occur in the legs -- and pulmonary embolism, a possibly fatal condition that occurs when a blood clot travels to the lungs.

Blood clots occur in some people in particular situations. Being immobilized after surgery, for instance, can lead to clots, and longer-than-average flights may also be a risk in others. Some factors may be related to a person's lifestyle, such as smoking and obesity, which can leave a person more vulnerable to clots.

Some studies have found that the taller a person is, the higher the risk clots could form.

In the new study, researchers followed the lives of nearly 27,000 adults for 12 years. They confirmed an association between height and clots among men, but found no similar patterns in women.

The tallest men -- those taller than 6 feet -- had double the risk of a blood clot than of men who were shorter than 5 ft, 8 inches. The conclusions took into account weight, smoking and diabetes factors. However, the findings do not prove that greater height itself is a risk factor for blood clots.

Lead researcher Dr. Sigrid K. Brakken, of the University of Tromso in Norway, said that they accounted for a number of factors that could have explained the link, but there also could be other variables involved that were not studied.  However, it is possible that taller height could affect the odds of clots in the veins due to a condition known as "venous stasis," or slowed blood flow in the veins, especially in the legs. The slower flow increases the risk for clotting, Brakken told Reuters in an email.

Brakken said that the reason the association is seen only in men, is most likely due to the fact that women, on average, do not grow as tall as men and, as such, is not as affected by clot risk.

The subjects in the study were Norwegian men and women between the ages of 25 and 96. They were followed for a 12-year period. During that time, 462 developed a first-time clot. The clots were often related to specific causes, like surgery or medical conditions such as cancer. Trauma was also a specific cause. In 42 percent of those cases, though, there were no "provoking" factors.

In men who were six feet or taller, there were 1.68 clots per 1,000 men per year. That number is double the amount of clots per 1,000 men who are shorter than 5 ft, 8 inches.

When weight and other factors were accounted for that affect clot risk, the tallest men still had twice the risk of the shortest men.

Besides height, which nothing can be done to decrease the risk, quitting smoking, losing excess weight, and getting regular exercise are all good measures to keep the risk of blood clots to a minimum.

Results of the study are found in the American Journal of Epidemiology.


On the Net: