High risk of venous thromboembolism after orthopedic surgery in patients with thrombophilia.

OBJECTIVE This study aimed at evaluating the effect of thrombophilia on the risk of VTE in patients undergoing any type of orthopedic surgery. BACKGROUND Patients undergoing orthopedic surgery are at high risk for venous thromboembolism (VTE). Whilst patients with thrombophilia have an increased risk of VTE, it is currently unclear whether there is a synergetic effect in patients with thrombophilia who undergo orthopedic 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) were used. Odds ratios (ORs) with 95% confidence intervals (CIs), adjusted for age, sex and body mass index (BMI) (ORadj) were calculated for patients undergoing any orthopedic intervention. RESULTS Of 4,721 cases and 5,638 controls, 263 cases and 94 controls underwent orthopedic surgery. Patients who had any orthopedic intervention in the year prior to the index date were at higher risk of VTE (ORadj 3.7; 95% CI, 2.9-4.8) than those who did not undergo any orthopedic surgery. There was an additionally increased risk in patients with factor V Leiden (OR 17.5, 95% CI 4.1-73.6), non-O blood group (OR 11.2; 95%CI 3.4-34.0) or elevated plasma levels of factor VIII (OR 18.6; CI 7.4-46.9) all relative to patients without these defects, not undergoing orthopedic surgery. CONCLUSIONS Patients with factor V Leiden, high levels of factor VIII or blood group non-O were found to have a high risk of VTE after orthopedic surgery. Identification of these patients may enable individualized thromboprophylactic treatment, to efficiently reduce VTE risk.