VPB1382 - Prolonged Post-operative Hypercoagulability Can be Defined Using Serial Thrombelastography in Patients with Metastatic Bone Disease

Background: Presence of malignancy places patients with metastatic bone disease (MBD) undergoing orthopaedic surgery at 7-fold higher risk for post-operative venous thromboembolism (VTE) compared to non-cancer orthopaedic patients. Thromboprophylaxis guidelines are undefined for this vulnerable group, as the extent and duration of post-operative hypercoagulability (and concomitant VTE risk) remain unknown.

Thrombelastography (TEG) is a point-of-care blood test that can evaluate coagulation, from clot formation to lysis. Maximal amplitude (MA) measures clot strength and values ≥65 mm can define hypercoagulability and predict VTE events in orthopaedic surgery patients.

Aims: Quantify the extent and duration of post-operative hypercoagulability and evaluate coagulation profiles in those with and without VTE events.

Methods: Consecutive adults with MBD undergoing orthopaedic surgery for fracture treatment were enrolled into this single-centre, prospective cohort study (HREBA.CC-20-0147). Patients provided informed consent to collect blood samples (pre-operatively; on post-operative day (POD) 1, 3, and 5; and 2-, 6-, and 12-weeks post-operatively) and undergo a bilateral lower extremity screening Doppler ultrasound on POD3. TEG analysis was performed using TEG®6s haemostasis analyzers (Haemonetics Corporation). Image-confirmed VTE was captured throughout the study and defined as symptomatic or asymptomatic. Thromboprophylaxis prescription and compliance were recorded. Descriptive statistics and one-sample t-tests were performed to compare MA values at VTE diagnosis with mean MA of patients without VTE complications.

Results: Nineteen participants (68±12 years) were enrolled. VTE incidence rate was 21.1% (Table1). At the time of VTE diagnosis, mean MA was 68.3±5.3 mm and all VTE events occurred by POD5. Within this timeframe, regardless of VTE incidence, most patients were hypercoagulable (POD3: 82.4%; 2-weeks: 91.7%). Hypercoagulability persisted at 6-weeks (mean MA: 65.0±4.7 mm) and normalized at 12-weeks (mean MA: 63.1±5.1 mm) post-operatively (Fig.1).

Conclusion(s): Patients with MBD are at highest risk for VTE complications within 2-weeks post-operatively. Duration of hypercoagulability may extend beyond 6-weeks post-operatively, warranting further investigation into disease-specific hypercoagulability thresholds.