BCS Guidance on thromboprophylaxis for flying

1. Travelling for >4 hr doubles the risk of VTE compared with not travelling.
2. The risk is highest in the first week following travel but persists for 2 months
3. The risk is similar to that incurred by travelling by car, bus or train over a similar period. Factor V Leiden mutation, height (>1.90 m and <1.6 m) and oral contraceptive use increase the risk of VTE, notably with air travel. Likewise, obesity (BMI >30 kg/m2) is associated with increased risk.
4. The relative risk of VTE is 3.45 for a flight of 4h. This risk is increased for multiple and for prolonged flights. The absolute risk of VTE in a fit person is of the order of 1/6000 for a flight of >4h.
5. Aspirin is not currently recommended in this context for DVT/VTE prophylaxis

Guidance for the avoidance of DVT and VTE
	Risk criteria	Risk reduction advice for passengers
Low risk	No History of DVT/VTE. No recent surgery (4 weeks). No other known risk factor.	Keep mobile. Drink plenty of non-­‐alcoholic drinks. Do not smoke. Avoid caffeine and sedative drugs.
Moderate risk	History of DVT/VTE. Surgery lasting >30 mins 4-8 weeks ago. Known clotting tendency. Pregnancy. Obesity (BMI > 30kg/m2).	As for ‘low risk’ with the addition of compression stockings.
High risk	Previous DVT with known additional risk including known cancer. Surgery lasting > 30 mins within the last 4 weeks.	As for ‘moderate risk’ but subcutaneous injection of Enoxaparin 40mg before the flight and on the following day*.
BMI= Body Mass Index. DVT= Deep Vein Thrombosis. VTE= Venous Thromboembolism.

*Note re Enoxaparin in high risk patients:

• Should be administered as Enoxaparin (Clexane) 40mg single dose syringe on the morning of the flight and on the following day.
• In severe renal impairment (eGFR <30 reduce dose to 20mg single dose syringe)
• Although rare compared with unfractionated heparin, complications including bleeding and thrombocytopenia can occur so it is only recommended in those at high risk.