Estimating Venous Thromboembolism Risk in Foot and Ankle Surgical Patients: A Base-Population Case-Control Study

CATEGORY: Complications INTRODUCTION/PURPOSE: Venous thromboembolism (VTE) is the leading cause of preventable hospital death. There are several risk factors for VTE of which orthopedic surgery is an important one. VTE risk is highest following major orthopedic surgery and therefore some form of prophylactic therapy is usually recommended here. In contrast, the risk for VTE following foot and ankle surgery is less clear and so are guidelines on VTE prophylaxis in these patients. The purpose is to estimate the risk of VTE and the duration of the increased risk period after foot and ankle surgery. METHODS: Data from a large population-based case–control study (the Multiple Environmental and Genetic Assessment of risk factors for venous thrombosis [MEGA] study) on the etiology of venous thrombosis were used (5129 cases; 5882 controls). Odds ratios (ORs) with 95% confidence intervals (CIs), adjusted for age, sex and body mass index (ORadj) were calculated for patients undergoing any foot or ankle intervention before the index date (VTE date or control date). RESULTS: 286 cases and 96 controls underwent any orthopedic intervention in the year before the index date for an ORadj of 3.7 (95%CI 2.9-4.8) The ORadj in the first 90-days was 11.4 (95%CI 7.3-17.7). 57 cases and 20 controls had a foot or ankle intervention in the year before the index date, resulting in a three-fold increased risk for VTE (OR 3.3, 95% CI 1,9-5.5). VTE risk was highest in the first 30 (ORadj 10.2,95%CI 3.0-33.9) and 90-days following surgery (ORadj 12.4, 95% CI 4.4-34.8). In 34 patients the surgery was trauma related while 43 patients underwent elective surgery. Traumatic surgery was associated with a higher risk compared with elective surgery for an OR of 13.9 (95%CI 1.8-108.4) and 8.3 (95%CI 1.9-36.9), respectively at 30-days. CONCLUSION: Foot and ankle procedures were associated with an increased VTE risk which was highest in the first 90-days following surgery. Trauma related surgery was associated with a higher VTE risk than elective surgery. These results are important to decide on thromboprophylactic measures following foot and ankle surgery.