Increased Risk of Recurrent Venous Thromboembolism during Hormone Replacement Therapy

Else Høibraaten; Erik Qvigstad; Harald Arnesen; Stig Larsen; Egil Wickstrøm; Per Morten Sandset

doi:10.1055/s-0037-1614156

Thrombosis and Haemostasis, Table of Contents

Thromb Haemost 2000; 84(06): 961-967
DOI: 10.1055/s-0037-1614156

Review Article

Schattauer GmbH

Increased Risk of Recurrent Venous Thromboembolism during Hormone Replacement Therapy

Results of the Randomized, Double-blind, Placebo-controlled Estrogen in Venous Thromboembolism Trial (EVTET)

Authors

Else Høibraaten
Erik Qvigstad

¹Department of Gynecology, Oslo, Norway
Harald Arnesen

²Department of Cardiology, Ullevål University Hospital, Oslo, Norway
Stig Larsen

³Parexel Medstat, Lillestrøm, Norway, and 4Novo Nordisk Pharma AS, Oslo, Norway
Egil Wickstrøm

⁴From the Department of Hematology, Hematological Research Laboratory, Oslo, Norway
Per Morten Sandset

Abstract

Summary

Recent observational studies suggest a 2-4 fold increased risk of venous thromboembolism (VTE) in women taking hormone replacement therapy (HRT). The present study was started before publication of these studies, and the aim was to determine if HRT alters the risk of VTE in high risk women. The study was a randomized, double-blind, and placebo-controlled clinical trial with a doubletriangular sequential design. Females with previously verified VTE were randomized to 2 mg estradiol plus 1 mg norethisterone acetate, 1 tablet daily (n = 71) or placebo (n = 69). The primary outcome was recurrent deep venous thrombosis (DVT) or pulmonary embolism (PE). Between 1996 and 1998 a total of 140 women were included. The study was terminated prematurely based on the results of circumstantial evidence emerging during the trial. Eight women in the HRT group and one woman in the placebo group developed VTE. The incidence of VTE was 10.7% in the HRT group and 2.3% in the placebo group. In the HRT group, all events happened within 261 days after inclusion. The sequential design did not stop the study, but strongly indicated a difference between the two groups. Our data strongly suggests that women who have previously suffered a VTE have an increased risk of recurrence on HRT. This treatment should therefore be avoided in this patient group if possible. The results also support those of recent epidemiological studies, which also indicate increased risk of VTE in non-selected female populations during HRT.

Key words

Clinical trial - venous thromboembolism - hormone replacement therapy - estrogen

Full Text

References

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