Idraparinux was noninferior to standard therapy for deep venous thrombosis but inferior for pulmonary embolism.

M e t h o d s Design: 2 randomized, controlled, noninferiority trials. Allocation: Concealed.* Blinding: Blinded (central outcome adjudication committee).* Follow-up period: 3 and 6 months. Setting: 318 centers in 25 countries in North and South America, Europe, Africa, and Australia/New Zealand. Patients: Patients ≥ 18 years of age with acute symptomatic DVT (n = 2904, mean age 58 y, 54% men) or PE (n = 2215, mean age 62 y, 52% women). Exclusion criteria included receipt of heparin for > 36 hours; need for thrombolysis, embolectomy, or a vena cava filter; another indication for a vitamin K antagonist; pregnancy; creatinine clearance < 10 mL/min; and uncontrolled hypertension. Intervention: Idraparinux, 2.5 mg subcutaneously once weekly (in patients with creatinine clearance < 30 mL/min, dose was 1.5 mg after the first injection) (n = 1452 in the DVT study and 1095 in the PE study), or standard therapy (tinzaparin, enoxaparin, or intravenous heparin followed by warfarin or acenocoumarol, with monitoring and dose adjustment as required) (n = 1452 in the DVT study and 1120 in the PE study). Treatment duration was either 3 mo (22% of patients in the DVT study and 9% in the PE study) or 6 months, based on the physician’s assessment of recurrence risk. Outcomes: Objectively confirmed symptomatic recurrent VTE, clinically relevant bleeding, and death from all causes. Patient follow-up: 99% (intention-to-treat analysis).