Venous thromboembolic (VTE) disease comprises of Deep venous thrombosis (DVT) and pulmonary thromboembolism (PTE) and are the major causes of morbidity and mortality in immobile patients. Here are some pertinent health statistics that may be of interest. This again reinforces the need to prepare using better primary health strategy’s for your next long-haul flight prior to your departure and importantly adopt good in-flight health skills. See flyinghealthprogram.com for more detail. 

There is observational evidence that intercontinental air travel is associated with a high incidence of DVT and PTE during or within 48 hours of long-distance flights. This may be more applicable with long-haul flights where flight time exceed 4 hours though we have entered the era of ultra-long-haul flights where flight time exceeds 14 hours with some traveling more than 18 hours.

Immobility together with several factors related to the aircraft cabin and the passenger, seem to act together to predispose to excessive blood coagulation, which can result in VTE.

More than a billion travellers fly each year; more than 225 million travel in and out of the UK each year (75% levels of 2019) and is increasing significantly. More than 5% of travellers may have chronic health problems and risk factors for VTE.

Interestingly it affects approximately 2–3 individuals per 1000 per year. VTE is the third cause of death by vascular diseases, only surpassed by myocardial infarction and ischemic stroke. In addition, it is the most common cause of preventable death in hospitalised patients. The annual incidence is 1/1,000 among the general population, 0.4–3/10,000 among travellers, and 1–2.5/10,000 among airplane passengers. In a cohort study of “healthy subjects”,  the absolute risk of VTE on flights lasting longer than 4 hours was found to be 1 in 6000. A meta-analysis involving 12 studies reported 4055 cases of VTE in trips lasting longer than 8 hours with studies including both air and overland trips with follow ups ranging from 2 to 8 weeks. The relative risk for VTE was 2.8 and at each increment of 2 hours in travel time, there was an approximate 10% increase in the risk of VTE. Considering only air travel, this risk increased to 26%, suggesting a cumulative effect of flight time in the genesis of VTE.

MacCallum et al. demonstrated that on flights lasting less than 4 hours, the risk of VTE was approx. 2X higher than patients who did not travel and remained high in the 4 subsequent weeks. In long-haul flights (greater than 12 hours as one or more flights), the risk of VTE was around 3X higher. After 12 weeks, no time0flight effect was observed in the occurence of thrombotic events. 

It is difficult to identify the true incidence owing to asymptomatic cases, and postmortem studies indicate higher incidence of deep vein thrombosis (DVT) than is known. Even though the incidence of symptomatic passenger thrombosis is unknown, it is believed that there are “30,000 cases per year” in the UK. This may be a significant impact on NHS resources with the current all time high waiting lists that we see today. 

Movement is key to life, to maintaining a healthy circulation and to flying long-haul.

Happy flying and keep safe.