AMSTERDAM – Women with an unprovoked index venous thromboembolism while they are on estrogen treatment have a low recurrence risk as long as they stop estrogen, and therefore don’t need prolonged anticoagulant treatment, based on a review of 630 cases.
Women whose index venous thromboembolism (VTE) occurred while on estrogen had 4 recurrences for every 10 among the women who had unprovoked VTE and were not on estrogen during an average follow-up of more than 6 years, Dr. Lisbeth Eischer said at the 24th Congress of the International Society on Thrombosis and Haemostasis.
"We propose that these women [whose index VTE occurred while on estrogen] should receive anticoagulant treatment for no longer than 3 months," said Dr. Eischer of the division of hematology and hemostasis at the Medical University of Vienna.
"I think the recommendation [for duration of anticoagulation] should be comparable to women who have undergone surgery, not more than 3 months," she said. In the review she presented, which included 630 women treated for a VTE since 1992, the average duration of anticoagulant treatment was 7 months among women whose VTE occurred when on estrogen as well as those not on estrogen at the time of their VTE.
Dr. Eischer and her associates studied women enrolled in the prospective Austrian Study on Recurrent Venous Thromboembolism (AUREC). The group of 630 included women aged 18 years or older who had a first VTE and received at least 3 months of anticoagulant treatment. The study excluded women with another identifiable cause of VTE, such as surgery, trauma, pregnancy, cancer, or significant thrombophilia. Women were not excluded if they were heterozygous for a factor V Leiden mutation. They averaged 46 years old; 361 (57%) had deep vein thrombosis as their index case, and 269 (43%) had pulmonary embolism as their index case. The average length of follow-up was 76 months (6.3 years).
Three hundred thirty-three (53%) women were on estrogen treatment at the time of their VTE. These women were significantly younger, averaging 38 years compared with an average of 55 among the women not receiving estrogen at the time of their VTE. The prevalence of women with a single factor V Leiden mutation was 48 (16%) among those not on estrogen and 98 (28%) among those on estrogen, a statistically significant difference.
During follow-up, the incidence of recurrent VTE was 22 (7%) among the 333 women whose index VTE occurred while on estrogen, and 49 (16%) among the 297 with an unprovoked index VTE. In a multivariate analysis that adjusted for age, location of the VTE (pulmonary or deep vein), and presence of a factor V Leiden mutation, women whose index VTE occurred while they were taking estrogen had a statistically significant 60% reduced rate of having a recurrent VTE during follow-up compared with the women whose index VTE occurred when they were not on estrogen.
Dr. Eischer said she had no relevant financial disclosures.
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