Genetic thrombophilia, 'the pill' hike VTE risk.(Clinical Rounds)

TORONTO -- A combination of inherited and acquired risk factors puts certain women in danger of developing venous thromboembolism, said Dr. Susan R. Kahn at the annual meeting of the Society of Interventional Radiology.

The incidence of venous thromboembolism (VTE) in women of child-bearing age with genetic thrombophilia who also take oral contraceptives is 2.85 per thousand--35 times higher than women of the same group with neither risk factor, whose incidence rate is a comparatively low 8 per 100,000.

"A woman between the ages of 28 and 45 with [genetic thrombophilia], such as the Factor V Leiden mutation, and who also uses oral contraceptives has an increased risk of thrombosis, but she may ultimately manage to avoid having a thrombotic episode. However, if she happens to undergo knee surgery at age 35, the added risk factor may tip her over the thrombosis threshold, and she may develop clinical VTE," said Dr. Kahn, a researcher of thromboembolic disorder epidemiology at McGill University, in Montreal.

The clinical complications from VTE--which is manifested as either deep-vein thrombosis (DVT) or pulmonary embolism (PE)--include death from PE, postphlebitic syndrome, and recurrent VTE. Some of the long-term complications include postthrombotic syndrome, which develops in 30%-40% of DVT patients despite treatment with anticoagulants, as well as chronic pulmonary hypertension, which develops in about 2% of PE patients.

Despite advances in thromboprophylaxis and treatment, the annualized incidence of VTE in the general population has remained one to two patients per 1,000 persons over the last 25 years. On average, a person can expect a 5% chance of developing VTE in their lifetime, and the incidence increases twofold with each decade of age. The incidence is also far greater in African and Caucasian populations than in Asians.

According to Dr. Kahn, understanding the etiology of ...