title: Does the type of hormone replacement therapy influence the risk of deep vein thrombosis? A prospective case-control study.
abstract: BACKGROUND
  Although hormone replacement therapy (HRT) is associated with an increased risk of deep vein thrombosis (DVT), it is not clear if the risk differs in users of combined estrogen-progestin HRT and estrogen-only HRT.
  
  
  METHODS
  We prospectively studied postmenopausal women with suspected DVT in whom HRT use status was ascertained and who subsequently had objective diagnostic testing to confirm or exclude DVT. Cases were patients with idiopathic DVT, in whom there were no DVT risk factors, and controls were patients without DVT, in whom there were also no DVT risk factors. The risk of DVT was determined in users of estrogen-progestin HRT and estrogen-only HRT by comparing the prevalence of current HRT use in cases with idiopathic DVT and controls without DVT (reference group). Multivariable regression analysis was done to adjust for factors that might confound an association between HRT use and the risk of DVT.
  
  
  RESULTS
  One thousand one hundred and sixty-eight postmenopausal women with suspected DVT were assessed, from whom 95 cases of idiopathic DVT and 610 controls without DVT and no DVT risk factors were identified. Estrogen-only HRT was associated with an increased risk for DVT that was not statistically significant [odds ratio (OR) = 1.22; 95% confidence interval (CI) 0.57, 2.61]. Estrogen-progestin HRT was associated with a greater than 2-fold increased risk for DVT (OR = 2.70; 95% CI 1.44, 5.07).
  
  
  CONCLUSIONS
  The risk of developing DVT may be higher in users of combined estrogen-progestin HRT than in users of estrogen-only HRT.
authors.affiliation: Department of Medicine, McMaster University, Hamilton, Canada. jdouket@mcmaster.ca
authors.forename: J D
authors.initials: JD
authors.lastname: Douketis
authors.forename: J A
authors.initials: JA
authors.lastname: Julian
authors.forename: C
authors.initials: C
authors.lastname: Kearon
authors.forename: D R
authors.initials: DR
authors.lastname: Anderson
authors.forename: M A
authors.initials: MA
authors.lastname: Crowther
authors.forename: S M
authors.initials: SM
authors.lastname: Bates
authors.forename: M
authors.initials: M
authors.lastname: Barone
authors.forename: F
authors.initials: F
authors.lastname: Piovella
authors.forename: A G
authors.initials: AG
authors.lastname: Turpie
authors.forename: S
authors.initials: S
authors.lastname: Middeldorp
authors.forename: P
authors.initials: P
authors.lastname: van Nguyen
authors.forename: P
authors.initials: P
authors.lastname: Prandoni
authors.forename: P S
authors.initials: PS
authors.lastname: Wells
authors.forename: M J
authors.initials: MJ
authors.lastname: Kovacs
authors.forename: M R
authors.initials: MR
authors.lastname: MacGillavry
authors.forename: L
authors.initials: L
authors.lastname: Costantini
authors.forename: J S
authors.initials: JS
authors.lastname: Ginsberg
mesh_terms: D000368:Aged; D015992:Body Mass Index; D016022:Case-Control Studies; D015914:Estrogen Replacement Therapy / Q000009:adverse effects*; D004967:Estrogens / Q000009:adverse effects; D005260:Female; D006801:Humans; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D017698:Postmenopause; D011372:Progestins / Q000009:adverse effects; D011446:Prospective Studies; D012306:Risk; D012307:Risk Factors; D020246:Venous Thrombosis / Q000209:etiology*
chemical_list: D004967:Estrogens; D011372:Progestins