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Keywords:

  • estrogens;
  • hormone replacement therapy;
  • pulmonary embolism;
  • recurrence;
  • venous thrombosis

Summary

Background

The optimal duration of anticoagulation for women who had venous thromboembolism (VTE) associated with estrogen use is unknown.

Objectives

To test the hypothesis that women who had a first VTE while using estrogens have a low risk of recurrence.

Methods

A Prospective cohort study of 630 women (333 estrogen users, 297 non-users) with a first VTE, who were followed for an average of 69 months after anticoagulation withdrawal. Women with a previous or secondary VTE, coagulation inhibitor deficiency, lupus anticoagulant, cancer, pregnancy, requirement of long-term antithrombotic therapy or homozygosity or double heterozygosity for factor V Leiden and/or the G20210A prothrombin mutation were excluded. The endpoint was objectively documented symptomatic recurrent VTE.

Results

VTE recurred in 22 (7%) estrogen users and in 49 (17%) non-users. After 1, 2 and 5 years, the cumulative probability of recurrence was 1% (95% confidence interval [CI], 0–2), 1% (95% CI, 0–2) and 6% (95% CI, 3–9) among estrogen users and 5% (95% CI, 2–7), 9% (95% CI, 6–13) and 17% (95% CI, 12–22) among non-users. Compared with non-users, estrogen users had an adjusted relative risk (RR) of recurrent VTE of 0.4 (95% CI, 0.2–0.8). Compared with non-users in the respective age groups, the RR of recurrence was 0.4 (95% CI, 0.2–0.8) among estrogen-containing-contraceptive users and 0.7 (95% CI, 0.3–1.5) among women using estrogen-containing menopausal hormone therapy.

Conclusions

Women who had their first VTE while using estrogens have a low risk of recurrent VTE. These women might not benefit from extended anticoagulant therapy.