NON-O BLOOD TYPE IS RISK FACTOR FOR VENOUS THROMBOEMBOLISM IN ORTHOPAEDIC TRAUMA PATIENTS

Patients with a non-O blood type are at increased risk for venous thromboembolism (VTE) based on data from large non-orthopaedic studies. The association between non-O blood type and major provoked VTE, including symptomatic deep vein thrombosis (DVT) and pulmonary embolism (PE) following major orthopaedic surgery is less well defined, especially in trauma patients with different injury types. Therefore, the aim of this study was to compare blood group and VTE incidence in trauma patients who required surgical treatment. Consecutive adult patients undergoing surgery for acute acetabular, pelvic, hip, femur, or humerus fractures at a Level 1 trauma centre were included from several prospective cohort studies. Exclusion criteria were prior VTE, pre-injury therapeutic anticoagulation, or pregnancy. Following informed or surrogate consent, patients underwent blood work that included blood typing and patients were followed for 3-months post-operatively. All patients received low-molecular weight-heparin (LMWH) thromboprophylaxis for 14 days post-operatively for upper extremity injuries, or 28 days for pelvic or lower extremity injuries. VTE was defined as symptomatic and image-confirmed PE or DVT, or asymptomatic DVT found on screening Doppler ultrasound on postoperative day three. T-tests, chi-square and Fisher's Exact tests were used to compare between those with and without VTE and logistic regression was used to evaluate potential risk factors for VTE. A total of 268 patients were included in this pre-planned analysis. There was a total of 13 VTE events (4.9%) in this cohort. There were no differences in age and sex between those with and without VTE (Table 1). Compared with type-O blood type, type-A blood carried a 16-fold increased risk for VTE, type-B carried a 17-fold, and type AB carried at 61-fold increased risk for VTE (Table 2). Sustaining an acetabular fracture was associated with the highest VTE risk, based on fracture type (Table 2). This study supports that non-O blood type is associated with a higher risk of provoked VTE following major orthopaedic fracture requiring surgical intervention. Further investigation, including von Willebrand factor and factor VIII levels, is warranted to better understand this relationship. For any figures or tables, please contact the authors directly.