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Abnormal Levels of Coagulation Factors Mean Increased Risk for Venous Thrombosis in Postmenopausal Women Who Take Hormones: Presented at ASH

By Sophie Bainbridge

ATLANTA, GA -- December 10, 2007 -- Preliminary data from two trials of the Women's Health Initiative (WHI) show that abnormalities in coagulation factor levels can identify postmenopausal women who are at increased risk of venous thrombosis (VT) if they elect to begin hormone replacement therapy (HRT).

Measurement of these factors may help women and their physicians make informed decisions about whether or not to take HRT, said Mary Cushman, MD, MSc, Professor of Medicine, University of Vermont, Burlington, Vermont, here at the 49th American Society of Hematology (ASH) Annual Meeting and Exposition.

Factors associated with an elevated VT risk in the presence of HRT included free protein S, D-dimer, and plasmin antiplasmin complex (PAP).

To determine if certain coagulation factors could identify women who would be at high risk of venous thrombosis if they take HRT, Dr. Cushman and colleagues conducted a nested case-control study that measured baseline levels of these factors in 215 women who developed VT and 867 age-matched controls. All of the women were participants in one of two placebo-controlled, double-blind, randomized WHI trials evaluating conjugated equine estrogens alone (E), or estrogen plus medroxyprogesterone acetate (E + P), or placebo.

The mean age of the women in this analysis was 66, and ranged from 50 to 79 years.

The investigators studied procoagulant, anticoagulant, and fibrinolysis markers in blood samples that were obtained at the time the women entered the WHI studies.

They found that women who had low levels of protein C and free protein S, and the highest levels of D-dimer, PAP, and prothrombin fragment 1-2 had an elevated risk of VTE.

The most important predictor of VTE risk was a high D-dimer level. For example, women with the highest levels of D-dimer who were on HRT had a 6-fold increase in their risk for VTE compared with women with the lowest levels of D-dimer who were randomized to placebo, Dr. Cushman said.

However, she cautioned that assays for D-dimer are currently problematic, with a lack of standardization. Because of this, "routine testing for D-dimer is not yet ready for prime time," she said.

"These results really are preliminary, and we need to do more studies to confirm our findings. But I think this is a first step in being able to tease out those women who will have an increased risk from hormonal therapy from those whose risk is comparatively small. Women want this information to help them make intelligent choices about whether or not to take HRT."


[Presentation title: Coagulation Factors, Postmenopausal Hormone Replacement Therapy and the Risk of Venous Thrombosis: The WHI Clinical Trials of Postmenopausal Hormone Therapy. Abstract 127]

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