The Use of Fondaparinux in Preventing Thromboembolism in High Risk Trauma Patients

Overview

Trauma patients are at high risk of developing deep vein thrombosis (DVT) and pulmonary embolism (PE). The incidence of DVT varies greatly from 5-63% among studies depending on patient's individual risk factors, modality of prophylaxis, and methods of detection. The incidence of PE may be as low (0.3-4.3%) but carries a mortality of 20-50% which makes prevention of DVT of the utmost importance. The current standard of care for DVT prophylaxis in the trauma patient with high risk of DVT is enoxaparin, a low molecular weight heparin, administered twice a day as long as anticoagulation in not contraindicated. Many studies have demonstrated its efficacy when compared to mechanical compression and to unfractionated heparin, however one of the most robust of these studies still reported an DVT incidence of 35% in patients treated with enoxaparin. Another drug, fondaparinux, is a selective factor Xa inhibitor that could offer added benefits over enoxaparin such as once daily dosing and a drastically reduced risk of heparin induced thrombocytopenia (HIT). Fondaparinux has been already be widely used in post-operative hip surgery and major knee surgery patients with good results. It has also been shown to be effective in DVT prophylaxis in patients who have had major abdominal surgery and also in acute medical patients. Fondaparinux has yet to be used in trauma patients. Trauma patients are a diverse and distinct population given the acuity of their injuries and their increased risk of bleeding who at this time still do not have a perfect method for DVT prophylaxis. We hypothesize that fondaparinux will be effective in decreasing the risk of DVT when used in the trauma patient population. This is a non randomized prospective cohort study designed to test the efficacy of fondaparinux in the prophylaxis of DVT and PE in trauma patients.

Patients with trauma admitted to San Francisco General Hospital and qualify for the study will be assigned to +fondaparinux and no fondaparinux arms based on guidelines that were developed for and are considered the standard of care for the use of low molecular weight heparin in the same group of patients for the same indication. These guidelines will separate patients at risk for DVT into those that are high risk and very high risk. The primary efficacy outcome measures will be DVT and PE. Presence of DVT will be assessed with serial color flow duplex ultrasound during the patients in hospital stay at weekly intervals up to 3 weeks and when the patient has symptoms of DVT. PE will be diagnosed according to clinical suspicion by the patients treating physicians and subsequent imaging by CT. We plan on enrolling approximately 100 patients in the +fondaparinux and 100 patients in the no fondaparinux arm. We will compare both the incidence of DVT and PE in these groups and to the incidences in the literature and historical controls. A second aim of the study is to evaluate the adverse outcomes such as increased bleeding in patients who receive fondaparinux. A third and final aim of the study is to describe the effect of fondaparinux on antifactor Xa levels in trauma patients.