Travel-related thrombosis.

Travel-related thrombosis is a serious public health concern considering the large and increasing number of travellers. Due to a lack of evidence, counselling air travellers on their venous thrombosis risk is not immediately straightforward, and advice will have to be based mostly on theoretical grounds. In this review a basis for these considerations is given. First of all it needs to be recognized that venous thrombosis is a multicausal disease, i.e. several risk factors have to be present before an event occurs. This is reflected in the literature where clearly increased risks have been described for certain groups, such as subjects with factor V Leiden, those who use oral contraceptives or are obese. Also, an increased risk for tall and short people has been reported. So, for subjects with a known risk factor who plan to travel, benefits and risks of thrombosis prophylaxis, (pharmacological or other), need to be weighed. This review provides some theoretical examples. For all other travellers, the advice to move and exercise as much as possible is likely to be sufficient.