High blood-clot risk with obesity confirmed

NEW YORK (Reuters Health) – Obesity boosts the risk of
venous thromboembolism — the formation in veins of blood clots
that can travel to the lungs — and is a particularly strong
risk factor among men and women under 40 years old, according
to a new report.

Obesity was first tied to fatal lung clots (aka, pulmonary
embolisms) in 1927, Dr. Paul D. Stein of St. Joseph Mercy
Hospital in Pontiac, Michigan, and colleagues note in the
American Journal of Medicine. There is also evidence that
excess weight may also increase the risk of deep venous
thrombosis. But there have been a number of difficulties in
verifying this association.

To investigate whether obesity is in fact a risk factor for
venous thromboembolism, Stein and his team reviewed 1979-1999
data from the National Hospital Discharge Survey, which
included discharge information for more than 12 million obese
patients and nearly 700 million patients not classified as
obese.

Obese patients were 2.5 times more likely to have deep
venous thrombosis than non-obese individuals, and 2.21 times
more likely to suffer a pulmonary embolism. As past research
has suggested, women’s risk of deep venous thrombosis was
somewhat greater than men’s.

The effect of obesity rose substantially among individuals
younger than 40, who had a more than 5-fold greater risk of
deep venous thrombosis or pulmonary embolism compared with
older patients.

Again, this risk was greater among women, with obese
females under 40 having a 6-fold increased risk of deep venous
thrombosis compared to non-obese young women.

Because the diagnosis of pulmonary embolism is frequently
missed, Stein noted in a press release accompanying the study,
the findings should “alert physicians to the possibility of
this diagnosis” in obese patients.

SOURCE: American Journal of Medicine, September 2005.