Is Using Fondaparinux (Blood Thinner) to Treat Lung Clot Cheaper Than Traditional Therapy

1. Patients 18 years of age or older who present with acute symptomatic pulmonary embolism and who require antithrombotic therapy

2. Diagnostic confirmation based on the following criteria

   1. intraluminal filling defect on spiral computed tomography (CT) or pulmonary angiography
   2. a high-probability ventilation-perfusion lung scan, or a nondiagnostic lung scan with documentation of deep-vein thrombosis, either by compression ultrasonography or by venography.
3. Primary outpatient MD of record is an SMDC MD or patient did not have an outpatient MD when this event occurred.
4. For the matched control (UFH) cohort only: unfractionated heparin utilized for initial antithrombotic therapy. (LMWH use is allowed initially in the fondaparinux arm.) Patient willingness to have fondaparinux injections administered as an outpatient by themselves, family members, or other caregivers.

Exclusion Criteria:

1. Patients will be ineligible for the study if they had received therapeutic doses of UFH or LMWH or oral anticoagulants for more than 24 hours;
2. Patient required thrombolysis, embolectomy, or a vena cava filter;
3. Anticoagulant therapy was contraindicated - for example, because of active bleeding or thrombocytopenia (a platelet count below 100,000 per cubic millimeter).
4. Patients are ineligible if they had an estimated creatinine clearance \< 30 mL/min.
5. Uncontrolled hypertension (systolic blood pressure greater than 180 mm Hg or diastolic blood pressure greater than 110 mm Hg);
6. Pregnancy
7. Physician has estimated the life expectancy to be less than three months.
8. Patients weighing > 150 kg
9. Indwelling epidural catheter
10. Inability to give informed consent