Is aspirin (acetylsalicylic acid) effective in preventing deep vein thrombosis (DVT) recurrence when apixaban (eliquis) is not affordable?

Aspirin for DVT Recurrence Prevention When Apixaban Is Not Affordable

Aspirin is less effective than apixaban for preventing DVT recurrence, but it is significantly better than no therapy and should be used when anticoagulants are not affordable or accessible. 1

Efficacy Comparison Between Aspirin and Anticoagulants

Relative Effectiveness

• Anticoagulants (including apixaban) are significantly more effective than aspirin for preventing recurrent VTE
• According to the 2021 CHEST Guidelines:
  • Reduced-dose DOACs prevent 46 fewer VTE events per 1,000 cases compared to aspirin or placebo 1
  • Rivaroxaban specifically prevents 39 fewer VTE events per 1,000 cases compared to aspirin 1
  • Aspirin prevents 53 fewer VTE events per 1,000 cases compared to no therapy 1

Numerical Benefit of Aspirin

• Aspirin reduces VTE recurrence by approximately 26% compared to placebo (hazard ratio 0.74) 2
• In real numbers, this translates to a recurrence rate of 4.8% per year with aspirin versus 6.5% per year with placebo 2

Clinical Decision Algorithm

1. First choice: Reduced-dose DOAC (apixaban 2.5mg twice daily) if affordable
2. Second choice: If DOACs unaffordable, aspirin 75-100mg daily
3. Worst option: No therapy at all

Dosing Considerations

• The recommended aspirin dose for VTE prophylaxis is 75-100mg daily 3
• Higher doses (>100mg) do not provide additional protection but may increase bleeding risk 3
• Multiple guidelines (ACCP, NICE, ESC) consistently recommend low-dose aspirin when anticoagulants cannot be used 1

Important Caveats and Considerations

Bleeding Risk

• Major bleeding rates are similar between aspirin and placebo (0.6% per year with placebo vs. 1.1% per year with aspirin) 1
• Bleeding risk with aspirin is generally lower than with full-dose anticoagulation

Patient Education

• Patients should understand that aspirin is significantly less effective than apixaban
• The decision to use aspirin represents a compromise between some protection and no protection
• Regular reassessment of ability to afford anticoagulation should be performed

Common Pitfalls to Avoid

• Mistaking aspirin as equivalent to anticoagulants in effectiveness 3
• Using unnecessarily high doses of aspirin (>100mg daily) which increases bleeding risk without improving efficacy 3
• Failing to reassess the possibility of returning to anticoagulation if financial circumstances change 1

Special Considerations

• For patients with unprovoked DVT who have completed initial anticoagulation therapy, aspirin provides a modest but meaningful reduction in recurrence risk 2
• The 2021 CHEST Guidelines explicitly state that aspirin should be considered over no therapy when anticoagulants are being discontinued 1

While aspirin is clearly inferior to apixaban for preventing DVT recurrence, it provides meaningful protection compared to no therapy and should be recommended when anticoagulants are unaffordable.