title: Hormone therapy and recurrence of venous thromboembolism among postmenopausal women.
abstract: OBJECTIVE
  The route of estrogen administration is an important determinant of the risk of the first venous thromboembolism (VTE) event in postmenopausal women using hormone therapy (HT). However, the impact of transdermal estrogens on VTE recurrence risk has not been investigated. The aim of our study was to assess the impact of HT by route of estrogen administration on the risk of recurrent VTE.
  
  
  METHODS
  A total of 1,023 consecutive postmenopausal women aged 45 to 70 years with a confirmed first VTE were recruited from an outpatient clinic of a hemostasis hospital unit between January 2000 and December 2008 and were followed for an average of 79 months after discontinuation of anticoagulation therapy.
  
  
  RESULTS
  Recurrent VTE occurred in 77 women (1.1% per year). During the follow-up, 130 women used HT (12.7%), including 103 transdermal estrogen users (10.0%) and 10 oral estrogen users (1.0%). After adjustment for potential confounders, there was no significant association between recurrent VTE and use of transdermal estrogens (hazard ratio, 1.0; 95% CI, 0.4-2.4), with the nonusers as a reference group. In contrast, women using oral estrogens had an increased risk of recurrent VTE (hazard ratio, 6.4; 95% CI, 1.5-27.3). Consistently, no subgroup of women had evidence of a risk of recurrent VTE with transdermal HT that significantly differed from that observed for all women.
  
  
  CONCLUSIONS
  Oral but not transdermal estrogens are associated with a higher risk of recurrent VTE among postmenopausal women. This result provides further epidemiological evidence that transdermal estrogens may be safe with respect to VTE risk.
authors.affiliation: Hormones and Cardiovascular disease team, CEPH Centre for Research in Epidemiology and Population Health, U1018, Inserm, F94807, Villejuit, France. valerie.olie@inserm.fr
authors.forename: Valérie
authors.initials: V
authors.lastname: Olié
authors.forename: Geneviève
authors.initials: G
authors.lastname: Plu-Bureau
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Conard
authors.forename: Marie-Hélène
authors.initials: MH
authors.lastname: Horellou
authors.forename: Marianne
authors.initials: M
authors.lastname: Canonico
authors.forename: Pierre-Yves
authors.initials: PY
authors.lastname: Scarabin
mesh_terms: D000279:Administration, Cutaneous; D000368:Aged; D015914:Estrogen Replacement Therapy / Q000009:adverse effects* / Q000706:statistics & numerical data; D004967:Estrogens / Q000008:administration & dosage* / Q000009:adverse effects; D005260:Female; D006801:Humans; D008875:Middle Aged; D017698:Postmenopause / Q000187:drug effects*; D012008:Recurrence; D012189:Retrospective Studies; D054556:Venous Thromboembolism / Q000139:chemically induced* / Q000453:epidemiology
chemical_list: D004967:Estrogens