title: The effect of prothrombotic blood abnormalities on risk of deep vein thrombosis in users of hormone replacement therapy: a prospective case-control study.
abstract: BACKGROUND
  Few studies have assessed the effect of prothrombotic blood abnormalities on the risk of deep vein thrombosis (DVT) with hormone replacement therapy (HRT).
  
  
  METHODS
  We studied postmenopausal women with suspected DVT in whom HRT use and prothrombotic blood abnormalities were sought. Cases had unprovoked DVT and controls had no DVT and without DVT risk factors. The risk of DVT was determined in women with and without prothrombotic abnormalities.
  
  
  RESULTS
  A total of 510 postmenopausal women with suspected DVT were assessed; 57 cases and 283 controls were identified. Compared to HRT, nonusers without the factor V Leiden mutation, the risk of DVT was increased in estrogen-progestin HRT users (odds ratio [OR], 3.2; 95% confidence interval [CI]: 1.2-8.6) and in nonusers with the factor V Leiden mutation (OR, 5.3; 1.9-15.4) and appears multiplied in users of estrogen-progestin HRT with the factor V Leiden mutation (OR, 17.1; 3.7-78). Compared to HRT, nonusers with normal factor VIII, the risk of DVT was increased in estrogen-progestin HRT users with normal factor VIII (OR, 2.8; 1.0-7.9) and in HRT nonusers with the highest factor VIII quartile (OR, 6.0; 2.1-17), and appears to be multiplied in women who are users of estrogen-progestin HRT with the highest factor VIII quartile (OR, 17.0; 3.6-80).
  
  
  CONCLUSIONS
  In postmenopausal women who are estrogen-progestin HRT users, the presence of the factor V Leiden mutation or an elevated factor VIII level appears to have a multiplicative effect on their overall risk of DVT, increasing it 17-fold compared to women without these blood abnormalities who are HRT nonusers.
authors.affiliation: Department of Medicine, McMaster University, Hamilton, Canada. jdouket@mcmaster.ca
authors.forename: Jim D
authors.initials: JD
authors.lastname: Douketis
authors.forename: Jim A
authors.initials: JA
authors.lastname: Julian
authors.forename: Mark A
authors.initials: MA
authors.lastname: Crowther
authors.forename: Clive
authors.initials: C
authors.lastname: Kearon
authors.forename: Shannon M
authors.initials: SM
authors.lastname: Bates
authors.forename: Marisa
authors.initials: M
authors.lastname: Barone
authors.forename: Franco
authors.initials: F
authors.lastname: Piovella
authors.forename: Saskia
authors.initials: S
authors.lastname: Middeldorp
authors.forename: Paolo
authors.initials: P
authors.lastname: Prandoni
authors.forename: Marilyn
authors.initials: M
authors.lastname: Johnston
authors.forename: Lorrie
authors.initials: L
authors.lastname: Costantini
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Ginsberg
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001769:Blood; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005165:Factor V / Q000235:genetics; D005260:Female; D020022:Genetic Predisposition to Disease; D020249:Hormone Replacement Therapy / Q000009:adverse effects / Q000379:methods*; D006801:Humans; D008875:Middle Aged; D017698:Postmenopause / Q000097:blood / Q000235:genetics; D011446:Prospective Studies; D011516:Prothrombin / Q000235:genetics*; D012307:Risk Factors; D020246:Venous Thrombosis / Q000097:blood* / Q000235:genetics
chemical_list: D005165:Factor V; D011516:Prothrombin