Blood Clot Risk Higher In Apple-Shaped Men And Pear-Shaped Women, Danish Study

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Main Category: Obesity / Weight Loss / Fitness
Also Included In: Cardiovascular / Cardiology;  Women's Health / Gynecology;  Men's health
Article Date: 29 Oct 2009 - 3:00 PDT

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New research from Denmark suggests that where middle-aged men and women carry excess body fat affects their risk of developing blood clots like deep vein thrombosis (DVT) , with apple-shaped men who carry excess fat mainly around the waist and pear-shaped women who carry excess fat mainly around the hips having the highest risk.

The study was the work of lead author Dr Marianne Tang Severinsen, a researcher in the Department of Clinical Epidemiology at Aarhus University Hospital in Aalborg in Denmark, and colleagues, and was published online in Circulation: Journal of the American Heart Association on 26 October.

Venous thromboembolism (VTE), also called deep vein thrombosis (DVT), is a significant cause of death in adults. It happens when a blood clot breaks free from one blood vessel and blocks the flow of blood in another. A typical VTE blood clot will travel from a vein in the leg to the lungs.

Previous studies have shown that obesity measured using Body Mass Index (BMI) as a marker of excess weight is linked to increased risk of developing life-threatening blood clots, but what remained unclear was how this related to the distribution of excess body fat in men and women.

Other studies have also suggested that increased hip size protects against arterial bloods clots, whereas this study now questions that in the case of middle aged women at least.

For the 10-year prospective study, which was funded by grants from the Herta Christensens Research Foundation and the Danish Obesity Research Center (DanORC), Severinsen and colleagues assessed the link between body mass, weight distribution and incidence of VTE in 27,178 men and 29,876 women who were between 50 and 64 years old at the start of the study.

The results showed a statistically significant positive link between any type of VTE and all measurements of body size, including body weight, BMI, total mass of body fat, waist size and hip size, in both men and women.

Severinsen and colleagues also found a direct relationship between VTE and weight distribution in both men and women.

And when they adjusted for waist and hip size, they found hip circumference was positively linked with VTE incidence in women but not men and waist circumference was positively linked to VTE incidence in men but not women. The link was just as strong when they took out the effect of possible confounders like smoking, exercise, height, blood pressure, diabetes, cholesterol and in the women, hormone replacement therapy (HRT).

Severinsen told the press that:

"The implications to the public are that all types of obesity increase the risk for VTE, but the location of body fat also plays some unknown role."

"For health professionals, the implication is that all types of fat distribution should be taken into account when evaluating risk for VTE," she stressed.

The researchers said the results challenge previous suggestions that large hips can protect against arterial thrombosis.

"Our study clearly shows that this is not the case for venous thrombosis," said Severinsen.

Severinsen and colleagues did not look at different types of fat tissue, but the results suggest that there is some difference between the type of fat distribution in VTE and that which puts people at higher risk of coronary heart disease.

She explained that studies have not reported any links between peripheral obesity as measured by hip size and coronary heart disease:

"Until now, the importance of fat distribution and VTE risk has not been evaluated," she said, adding that:

"Our hypothesis was that fat tissue was a risk factor for VTE, independent of the distribution of the fat, and we established this."

The researchers recommend that further studies be done to explore the underlying mechanisms of these links.

We should bear in mind that the study has at least one limitation in that it did not take into account possible weight change among the participants during follow up. For instance, if some obese participants gained more weight than the slim ones during follow up, the analysis would then underestimate the effect of obesity on the figures.

"Anthropometry, Body Fat, and Venous Thromboembolism. A Danish Follow-Up Study."
Marianne Tang Severinsen, Søren Risom Kristensen, Søren Paaske Johnsen, Claus Dethlefsen, Anne Tjønneland, and Kim Overvad.
Circulation published October 26, 2009.
DOI:10.1161/CIRCULATIONAHA.109.863241

Additional Sources: American Heart Association.

Written by: Catharine Paddock, PhD
Copyright: Medical News Today
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