To quantify the risk of venous thromboembolism (VTE) following air travel and assess methods of prevention.
Review of literature.
We reviewed Pubmed, Medline, Embase and Cochrane Databases for studies that have assessed the risk of VTE associated with air travel.
There is an association of VTE with air travel with pooled odds ratio of 1.59 (confidence interval 1.04-2.43) from three case control studies and relative risk of 2.93 (confidence interval 1.5-5.58) from two controlled cohort studies. The incidence of symptomatic pulmonary embolism (PE) is extremely low but there is substantial increase when the distance travelled is more than 5,000 miles (1.5 PE per million passengers) or time of flight is more than 8h duration (2.57 PE per million passengers). The quantitative risk of lower limb venous thrombosis in high-risk subjects is 5% per flight and 1.6% per flight for low risk subjects following long haul flights. All six randomised trials to test the below knee compression stockings with ankle pressures of 14-30 mmHg have shown reduction in lower limb venous thrombosis.
VTE is more common in those with additional risk factors when the risk is about 5% per air travel for long haul flights. Class I or II below knee compression stockings are effective in the prevention of lower limb venous thrombosis.