What is the preferred choice between Aspirin (acetylsalicylic acid) and Eliquis (apixaban) for venous thromboembolism (VTE) prophylaxis post hip orthopedic surgery?

Eliquis (Apixaban) vs. Aspirin for VTE Prophylaxis After Hip Surgery

For VTE prophylaxis after hip orthopedic surgery, low-molecular-weight heparin (LMWH) is the first-line recommendation, with apixaban (Eliquis) being a superior alternative to aspirin when LMWH cannot be used.

Comparative Efficacy and Safety

Apixaban (Eliquis)

• Dosage: 2.5 mg twice daily, starting 12-24 hours after surgery
• Duration: Recommended for 35 days after hip replacement 1, 2
• Efficacy: Superior to enoxaparin (LMWH) in preventing VTE in hip replacement surgery (1.4% vs 3.9% VTE incidence) 1
• Safety: Associated with lower rates of major bleeding compared to enoxaparin in clinical trials 1

Aspirin

• Efficacy: Considered less effective than anticoagulants for VTE prophylaxis 1, 3
• Evidence: ACCP guidelines specifically advise against aspirin as sole prophylaxis (Grade 2C recommendation) 1
• Status: Considered a third-line option after LMWH and direct oral anticoagulants (DOACs) 1

Decision Algorithm for VTE Prophylaxis After Hip Surgery

1. First-line: LMWH (if no contraindications) 1

   • Preferred for its established efficacy and safety profile
   • Extend prophylaxis up to 35 days for hip replacement

2. If LMWH is unavailable or contraindicated:

   • Preferred alternative: Apixaban 2.5 mg twice daily 1, 3
     • Advantages: Oral administration, no monitoring required, effective VTE prevention
     • Duration: 35 days for hip replacement surgery

3. Consider aspirin only if:

   • Patient has contraindications to both LMWH and DOACs
   • Patient has very low VTE risk and high bleeding risk
   • Used in combination with mechanical prophylaxis (IPCD)

Important Clinical Considerations

• Timing: Apixaban should be initiated 12-24 hours after surgery once hemostasis is established 3, 2
• Renal function: Apixaban is preferred over other DOACs in patients with moderate renal impairment (CrCl 30-50 mL/min) 3
• Drug interactions: Apixaban has potential interactions with CYP3A4 inhibitors and P-glycoprotein inhibitors 2, 4
• Bleeding risk: While apixaban has a favorable bleeding profile, there is no specific antidote readily available in all settings 4

Common Pitfalls to Avoid

1. Premature initiation: Starting apixaban too soon after surgery (before adequate hemostasis) increases bleeding risk
2. Inadequate duration: Stopping prophylaxis too early (before 35 days for hip replacement) increases VTE risk
3. Inappropriate dosing: Using treatment doses rather than prophylactic doses
4. Overlooking drug interactions: Failing to adjust for medications that affect apixaban metabolism
5. Aspirin limitations: Relying solely on aspirin when a patient has high VTE risk factors

In conclusion, while aspirin has been used for VTE prophylaxis, the evidence strongly supports apixaban as a more effective option after hip replacement surgery when LMWH cannot be used. The oral administration of apixaban offers convenience advantages over injectable LMWH while providing superior protection against VTE compared to aspirin.