Predictors of venous thromboembolism in patients with primary sarcoma of bone

Abstract

Venous thromboembolism (VTE) is known to be independently associated with both orthopaedic surgery and malignancy. Patients undergoing surgery for musculoskeletal malignancies are at an increased risk for thromboembolic events. Although VTE can lead to serious morbidity and mortality, the potential complications of prophylactic anticoagulation call for a greater understanding of a patient's risk factors, as well as more rigorous guidelines for prophylactic anticoagulation regimens. The aims of this study were to 1) Analyze the rate of VTE in patients surgically treated for primary bone sarcoma; 2) Identify risk factors for VTE in patients with primary bone sarcoma; 3) Discuss the complications associated with prophylactic anticoagulation in patients with primary bone sarcoma.

Methods: This retrospective study identified all patients 18 years and older treated surgically at our institution for a primary bone sarcoma between 1990 and 2015. All patients with at least 90 days of post-operative follow-up from the index surgery were analyzed for occurrence of VTE. Those with an event were compared to those without to identify predictors of VTE.

Results: 21 patients (5.5%) had a clinically symptomatic, radiographically confirmed VTE within 90 days of index surgery (12 DVT, 9 PE). Higher preoperative white blood cell count (OR 1.15, 95% CI 1.01-1.29) and post-operative wound complications (OR 5.01, 95% CI 1.93-13.55) were found to be independent risk factors for VTE. No differences in terms of efficacy were found among medications. The risk of wound complications increased significantly in patients who received chemical prophylaxis (OR 2.21, 95% CI 1.00-4.87).

Conclusions: Our patient population had a relatively low rate of VTE as compared to the literature. Preoperative white blood cell count (WBC) and post-operative wound complications were both found to be independently associated predictors for VTE in patients with primary bone sarcoma. An elevated WBC may reflect hemoconcentration which per se is prothrombotic in nature. Aggressive DVT prophylaxis may, counter intuitively, increase the risk of thromboembolic events due to prolonged immobilization and additional surgeries that usually occur when addressing postoperative wound complications such as postoperative hematoma and wound dehiscence that may relate to overanticoagulation. Prospective randomized trials comparing different medications in combination with compressive devices are needed to assess efficacy with the lowest complication profile. Simpler protocols may increase patient compliance to prophylactic treatment.

Keywords: Primary bone sarcoma; Prophylactic anticoagulation; Venous thromboembolism.