What is the recommended prophylaxis for patients at high risk of Venous Thromboembolism (VTE)?

VTE Prophylaxis for High-Risk Patients

For patients at high risk of VTE, pharmacologic prophylaxis with LMWH, low-dose unfractionated heparin (UFH), or fondaparinux is strongly recommended throughout hospitalization unless active bleeding or high bleeding risk contraindicates anticoagulation. 1, 2

Risk Stratification

Use validated risk assessment tools to identify high-risk patients:

• Padua Prediction Score ≥4 indicates high VTE risk (11% incidence without prophylaxis vs 2.2% with prophylaxis) 2
• IMPROVE VTE score ≥2 indicates increased VTE risk 2
• High-risk features include: acute medical illness with reduced mobility, active cancer, recent VTE (<3 months), obesity, age >60 years, thrombophilia, and immobilization 1, 2

Pharmacologic Prophylaxis Regimens

Acutely Ill Medical Patients (Non-Surgical)

Select one of the following options 1, 2:

• Enoxaparin 40 mg subcutaneously once daily 1
• Dalteparin 5000 IU subcutaneously once daily 1
• Fondaparinux 2.5 mg subcutaneously once daily (reduce to 1.5 mg once daily if CrCl 30-50 mL/min) 1
• UFH 5000 units subcutaneously three times daily (particularly for cancer patients) 1, 2

Duration: Continue throughout hospitalization (typically 6-14 days); do not extend beyond hospital discharge 1, 2

Surgical Patients (Non-Orthopedic)

For patients undergoing major surgery for cancer or other conditions 1:

• Enoxaparin 40 mg subcutaneously once daily starting preoperatively 1
• Dalteparin: Low risk: 2500 IU once daily; High risk: 2500 IU 12 hours after surgery, then 5000 IU once daily 1
• Fondaparinux 2.5 mg subcutaneously once daily 1
• UFH 5000 units subcutaneously twice or three times daily 1

Duration: Minimum 7-10 days; extended prophylaxis for 4 weeks (up to 35 days) is strongly recommended for major abdominal/pelvic surgery in cancer patients with high-risk features (restricted mobility, obesity, history of VTE) 1

Orthopedic Surgery Patients

For hip or knee replacement 1:

• Enoxaparin 30 mg subcutaneously twice daily starting 12 hours before or after surgery 1
• Rivaroxaban 10 mg orally once daily starting 6-10 hours after surgery once hemostasis established 1, 3

Duration: 10-14 days minimum; consider extending to 35 days for hip replacement 1

Cancer Patients (Specific Considerations)

Hospitalized cancer patients with acute illness or reduced mobility 1:

• LMWH or fondaparinux (when CrCl ≥30 mL/min) or UFH are recommended 1
• Direct oral anticoagulants are NOT recommended routinely in this setting 1

Ambulatory cancer patients receiving chemotherapy 1:

• Pancreatic cancer (locally advanced/metastatic): LMWH or direct oral anticoagulants (rivaroxaban or apixaban) recommended 1
• Khorana score ≥2: Direct oral anticoagulants (rivaroxaban or apixaban) recommended if not actively bleeding 1
• Multiple myeloma on immunomodulatory drugs: Use LMWH, low-dose aspirin (100 mg daily), or apixaban at prophylactic doses 1

Mechanical Prophylaxis

For patients with active bleeding or high bleeding risk (platelet count <50,000/mcL, recent CNS/spinal bleeding) 1, 2:

• Intermittent pneumatic compression (IPC) devices are preferred over graduated compression stockings 1, 2
• Graduated compression stockings (15-30 mmHg) are an alternative 2
• Mechanical methods should NOT be used as monotherapy unless pharmacologic prophylaxis is contraindicated 1

Critical Pitfalls to Avoid

Underdosing in obese patients: Standard fixed-dose LMWH may be inadequate in obese patients (BMI >30); consider weight-adjusted dosing (0.5 mg/kg enoxaparin every 12 hours) 4, 5

Premature discontinuation: Stopping prophylaxis too early significantly increases thrombotic risk; ensure minimum duration is met 1, 3

Rivaroxaban in medical patients: Do NOT use rivaroxaban for VTE prophylaxis in acutely ill general medical patients—the MAGELLAN trial showed increased bleeding risk without clear benefit 1

Bridging anticoagulation: For patients on chronic anticoagulation requiring surgery, only bridge if moderate-to-high thrombotic risk (recent VTE <3 months, active cancer); use LMWH when INR <2.0, stop morning before surgery, resume prophylactic LMWH 12 hours post-op and therapeutic LMWH at 48 hours once hemostasis assured 1

Renal impairment: Avoid fondaparinux and LMWH if CrCl <15 mL/min; use UFH instead 1, 3