Venous thrombosis after long-haul flights

Area of Science:

• Vascular Medicine
• Public Health
• Epidemiology

Background:

• The association between long-haul flights and venous thromboembolism (VTE) is a debated topic.
• Assessing the incidence of flight-associated thrombosis is crucial for understanding travel-related health risks.

Purpose of the Study:

• To prospectively evaluate the incidence of venous thrombosis in passengers undertaking long-haul flights.
• To compare thrombosis rates between long-haul travelers and a non-traveling control group.

Main Methods:

• A prospective, controlled cohort study involving 964 long-haul flight passengers (≥8 hours) and 1213 controls.
• Exclusion criteria included anticoagulant use and compression stocking use.
• Outcomes measured: ultrasonographically diagnosed calf muscle and deep vein thrombosis, symptomatic pulmonary embolism, and death.

Main Results:

• Venous thrombotic events occurred in 2.8% of passengers versus 1.0% of controls (Risk Ratio [RR], 2.83).
• Isolated calf muscle venous thrombosis was diagnosed in 2.1% of passengers and 0.8% of controls (RR, 2.52).
• Deep venous thrombosis occurred in 0.7% of passengers and 0.2% of controls (RR, 4.40); all cases had pre-existing risk factors.

Conclusions:

• Flights of 8 hours or longer significantly increase the risk of isolated calf muscle venous thrombosis.
• This elevated risk extends to deep venous thrombosis, particularly in individuals with established risk factors.
• Flight-associated thrombosis was exclusively identified in passengers with known risk factors for venous thrombosis.