title: Risk factors for recurrent venous thromboembolism in young and middle-aged women.
abstract: BACKGROUND
  It is a matter of debate whether women with an episode of VTE associated with estrogen have a lower risk of recurrence than women with an unprovoked VTE.
  
  
  OBJECTIVE
  To identify risk factors for recurrent VTE in women and to assess the risk of recurrent VTE associated with combined oral contraceptives (CHC) or menopausal hormone treatment (HT), compared to surgery-related and unprovoked VTE.
  
  
  METHODS
  A cohort of 974 women aged 18-64 years with a first episode of VTE were followed-up for a median time of 5.2 years. All women were previously included as cases in the Swedish nation-wide case-control study "Thrombo Embolism Hormone Study" (TEHS). Hazard ratios for recurrence were calculated using univariable and multivariable Cox proportional hazards model.
  
  
  RESULTS
  A total of 102 patients (10%) suffered from recurrent VTE. The annual rate of recurrence was 1.0% in patients with surgery/cast, 2.0% in patients with CHC/HT and 3.2% in patients with unprovoked first VTE. Adjusted hazards ratio (HRa) for recurrence was 0.35 (95% CI 0.20-0.61) in women with VT provoked by surgery/cast while women with estrogen-associated VTE had a HRa of 0.70 (95% CI 0.43-1.20) compared to women with unprovoked VTE.
  
  
  CONCLUSIONS
  Women 18-64 years are at low risk of recurrent VTE. Women with hormone associated VTE had a lower risk of recurrence than women with unprovoked VTE, but not as low as surgery/cast provoked VTE.
authors.affiliation: Department of Clinical Science and Education, Internal medicine, Södersjukhuset, Karolinska Institutet, Stockholm, Sweden. Electronic address: maria.ljungqvist@ki.se.
authors.forename: Maria
authors.initials: M
authors.lastname: Ljungqvist
authors.affiliation: Department of Clinical Science and Education, Internal medicine, Södersjukhuset, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Kristina
authors.initials: K
authors.lastname: Sonnevi
authors.affiliation: Centre for Pharmacoepidemiology, Department of Medicine, Solna, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Annica
authors.initials: A
authors.lastname: Bergendal
authors.affiliation: Coagulation Unit, Hematology Centre Karolinska, Department of Medicine Solna Karolinska Institutet, Stockholm, Sweden.
authors.forename: Margareta
authors.initials: M
authors.lastname: Holmström
authors.affiliation: Centre for Pharmacoepidemiology, Department of Medicine, Solna, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Helle
authors.initials: H
authors.lastname: Kieler
authors.affiliation: Department of Clinical Science and Education, Internal medicine, Södersjukhuset, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Gerd
authors.initials: G
authors.lastname: Lärfars
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D015331:Cohort Studies; D004967:Estrogens / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008875:Middle Aged; D012008:Recurrence; D012307:Risk Factors; D013548:Sweden / Q000453:epidemiology; D054556:Venous Thromboembolism / Q000453:epidemiology*; D055815:Young Adult
chemical_list: D004967:Estrogens
keywords: Estrogens; Recurrence; Risk Factors; Venous Thromboembolism; Women