Low-Dose Aspirin for DVT Prevention During Air Travel
Low-dose aspirin is not recommended as a first-line preventive measure for DVTs during air travel for most travelers, as there is insufficient evidence supporting its effectiveness compared to other interventions. 1, 2
Risk Assessment for Travel-Related VTE
The absolute risk of developing a symptomatic DVT from air travel is very low:
- Approximately 1 in 4,600 flights for journeys >4 hours 1
- Estimated absolute risk for symptomatic DVT is ~0.05% 1
- Risk increases with flight duration, particularly for flights >8-10 hours 1
Risk Stratification
Low-Risk Travelers (no additional risk factors):
- No pharmacological prophylaxis recommended 1
- Non-pharmacological measures should be employed:
- Frequent ambulation
- Calf muscle exercises
- Aisle seating when possible 1
- Maintaining adequate hydration
High-Risk Travelers (one or more risk factors):
Risk factors include:
- Previous VTE
- Recent surgery or trauma
- Active malignancy
- Pregnancy or postpartum status
- Estrogen use
- Advanced age
- Limited mobility
- Severe obesity
- Known thrombophilic disorder 1
Prevention Recommendations Based on Risk
For Low-Risk Travelers:
- Non-pharmacological measures only
- Aspirin is not recommended 1
For High-Risk Travelers (in order of preference):
- First choice: Properly fitted below-knee graduated compression stockings (15-30 mmHg) 1, 2
- Second choice: Prophylactic LMWH for flights >4 hours 1, 2
- Third choice (if options 1 and 2 are not feasible): Aspirin rather than no prophylaxis 1, 2
Evidence on Aspirin Effectiveness
- The LONFLIT3 study showed that in high-risk subjects, aspirin reduced DVT incidence to 3.6% compared to 4.8% in controls, but this was not statistically significant 3
- LMWH was significantly more effective than aspirin, with DVT rates of 0% versus 3.6% 3
- One analysis estimated that 17,000 travelers would need to be treated with aspirin to prevent one additional DVT if the baseline rate is 20 per 100,000 travelers 4
Important Considerations and Caveats
- Aspirin is not considered a reasonable alternative to anticoagulant therapy for those at high risk 1
- The American Society of Hematology specifically states that graduated compression stockings or LMWH should be used before considering aspirin 1
- Aspirin may cause gastrointestinal side effects in some patients (reported in 13% of patients in one study) 3
- The British Journal of Haematology guidelines recommend anticoagulants over anti-platelet drugs when pharmacological prophylaxis is considered appropriate 5
Conclusion
For most travelers, the risk of DVT during air travel is very low and does not warrant aspirin prophylaxis. For high-risk travelers, properly fitted compression stockings or LMWH are more effective than aspirin. Aspirin should only be considered as a third-line option when compression stockings and LMWH are not feasible.