Extended Prophylactic Anticoagulation Following Spinal Surgery for Metastatic Disease

Inclusion Criteria: * Age 18 years or older * Undergone spinal surgery (any approach) for treatment of vertebral metastatic disease at UPMC Presbyterian, Shadyside, or Mercy Hospital * Planned for discharge to home or acute rehabilitation facility (not hospice) * Willing and able to provide written informed consent * Able to take oral medications * Access to a telephone for follow-up calls Exclusion Criteria: * Already receiving therapeutic anticoagulation for another indication (e.g., atrial fibrillation, prior VTE, mechanical heart valve) * Planned initiation of therapeutic anticoagulation within the next 30 days for another indication * Known allergy or hypersensitivity to apixaban * History of pathological bleeding (e.g., intracranial hemorrhage, gastrointestinal bleeding requiring transfusion or endoscopic intervention within the past 6 months) * Active bleeding at time of planned enrollment * Platelet count less than 50,000/mm³ at time of enrollment * Hemoglobin less than 8 g/dL at time of enrollment * Serum creatinine greater than 2.5 mg/dL * ALT or AST greater than 3 times the upper limit of normal * Total bilirubin greater than 2 times the upper limit of normal * Known severe hepatic impairment (Child-Pugh Class C) * Pregnancy or breastfeeding * Women of childbearing potential unwilling to use adequate contraception during study participation * History of proximal gastrointestinal resection (i.e., gastrectomy and/or proximal small bowel resection) that might alter oral drug absorption * Concurrent use of strong dual inhibitors of CYP3A4 and P-gp or moderate CYP3A4 inhibitors (ketoconazole, itraconazole, ritonavir, clarithromycin, diltiazem) * Concurrent use of strong dual inducers of CYP3A4 and P-gp (rifampin, carbamazepine, phenytoin, St. John's Wort) * Inability to safely discontinue all antiplatelet medications for the 30-day study drug period, as determined by the treating cardiologist or prescribing physician (aspirin, clopidogrel, ticagrelor) * Inability or unwillingness to discontinue chronic NSAID use during the 30-day study drug period (as-needed use less than 3 days per week is acceptable) * Planned surgery or invasive procedure within the next 30 days * Hospital length of stay 30 days or greater * Prisoner or incarcerated individual * Any other condition that, in the investigator's opinion, would make the subject unsuitable for study participation or unable to comply with study procedures