Effects of raloxifene and continuous combined hormone therapy on haemostasis variables: a multicenter, randomized, double-blind study

Introduction: Hormone replacement therapy is known to increase the risk of thromboembolic events. We compared the effects of HRT and raloxifene on some haemostasis variables. Materials and methods: In a multicenter, double-blind study, 54 healthy postmenopausal women were randomized to receive either continuous treatment with 2 mg 17h-estradiol plus 1 mg norethisterone acetate (n =30) or 60 mg raloxifene (n =24) daily for 12 months. Blood samples were collected at baseline and at 3, 6 and 12 months to evaluate therapy effects on some aemostasis variables (factor VII, factor VIII, prothrombin fragments 1 and 2, protein C, protein C activity, protein S, thrombin—antithrombin complex, D-dimer, antithrombin, fibrinogen and plasminogen activator inhibitor). Results: Both raloxifene and continuous combined hormone therapy modified the haemostasis variables toward a more prothrombotic profile. Factor VIII ( p b0.01) and fibrinogen ( p b0.05) plasma levels significantly increased at 6 months, prothrombin fragments 1 and 2 ( p b0.05) significantly increased at 12 months, whereas protein C activity ( p b0.001) and antithrombin ( p b0.01) significantly decreased at 12 months in both groups. Conclusions: Our results demonstrate that raloxifene and continuous combined hormone therapy exhibit the same prothrombotic profile. Both treatments induced an increase in procoagulant parameters at 6 months and a decrease in anticoagulant parameters at 12 months.