Introduction: Venous Thromboembolism (VTE) is a leading cause of mortality among hospitalized patients [1]. In the United States, Pulmonary Embolus (PE) causes almost 300,000 deaths per year [2]. 12% of annual deaths are due to VTE [3]. Major orthopaedic surgery (e.g., hip or knee replacement) is associated with a high risk for postoperative VTE [1,4,5]. In hip fracture surgery without thromboprophylaxis, the incidence of VTE reported is 35% with venography, and symptomatic VTE is about 3% [6].

Because the clinical diagnosis of VTE is unreliable and its first manifestation may be a life-threatening PE, it is recommended that patients undergoing hip or knee replacement receive routine thromboprophylaxis with anticoagulant therapy after surgery unless they have contraindications to anticoagulant therapy [1,4,7,8].

This study quantifies the efficacy and safety of enoxaparin (LMWH) versus dabigatran (Indirect Anti-X) in patients with hip fractures.

Material and Methods: This prospective randomized study compared daily doses of LMWH 40 mg subcutaneously with Indirect Anti-X 220 mg orally in consecutive patients with hip fractures. Patients were evaluated with Doppler scans for deep DVT on postoperative days 5 and 30 and with a clinical evaluation on postoperative days 30, 45, 90, and 120.

Results: 330 study patients. LMWH Group: 165 patients (males 38%). Average age 72.4 years (range 32 to 84 years). Day 5 postoperative Doppler scan detected 1 asymptomatic distal DVT. Another patient later (in the period between day 5 to 30 day control) presented with signs of a PE and had a Doppler scan positive for proximal DVT. The V/Q scan was positive and the patient was treated per standard guidelines. Day 30 Doppler scan detected 11 DVTs (3 proximal and 8 distal). 4 of these were symptomatic (1 proximal and 3 distal). All were evaluated in the emergency department. After diagnosis, 2 were readmitted for studies and treatment, and 2 were discharged home. All 4 of these patients were started on LMWH as suggested by local guidelines. The overall incidence of PE in this group was 0.6%. Doppler scan detected DVTs in 6.6% (symptomatic 2.4%) of the LMWH group. 2 patients returned for the evaluation of bleeding, 2 for superficial wound infections and 3 for thigh hematomas.

Anti-X Group: 165 patients (males 43.3%) enrolled. Average age 69.3 years (range 18 to 73 years). Day 5 postoperative Doppler scan detected no DVTs. The postoperative day 30 Doppler scan detected 5 DVTs (1 proximal and 4 distal). An additional patient was diagnosed with a PE (V/Q scan positive, Doppler scan negative). 2 symptomatic patients (one with distal DVT who developed symptoms during in-hospital rehabilitation and one with a proximal DVT) were readmitted and treated per standard guidelines. The incidence of PE in this group was 0.68%, with Doppler scan-detected DVTs 3% (1.2% symptomatic). 1 patient had an hematoma involving 2/3 of the thigh, 1 had a wound infection, and 2 had a rash.

There were no significant differences between the two thromboprophylactic treatments, and the Fishers exact test was not significant for any individual complication or total number of complications. No patient died during the study period.

Conclusion: Both LMWH and Anti-X appear to be equally effective prophylactic medications for the prevention of deep venous thrombosis after proximal femur fracture surgery. The cost benefits of using Anti-X may be considerable.