title: The risk of recurrence in women with venous thromboembolism while using estrogens: a prospective cohort study.
abstract: BACKGROUND
  The optimal duration of anticoagulation for women who had venous thromboembolism (VTE) associated with estrogen use is unknown.
  
  
  OBJECTIVE
  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.
authors.affiliation: Department of Medicine I, Medical University of Vienna, Vienna, Austria.
authors.forename: L
authors.initials: L
authors.lastname: Eischer
authors.forename: S
authors.initials: S
authors.lastname: Eichinger
authors.forename: P A
authors.initials: PA
authors.lastname: Kyrle
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000368:Aged; D000925:Anticoagulants / Q000627:therapeutic use; D001317:Austria; D004967:Estrogens / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008875:Middle Aged; D011336:Probability; D011446:Prospective Studies; D012008:Recurrence; D012307:Risk Factors; D016896:Treatment Outcome; D054556:Venous Thromboembolism / Q000175:diagnosis* / Q000188:drug therapy* / Q000209:etiology
chemical_list: D000925:Anticoagulants; D004967:Estrogens
keywords: estrogens; hormone replacement therapy; pulmonary embolism; recurrence; venous thrombosis