Recent correspondence by Michael Mant states that the association between air travel and venous thromboembolism is weak.1 However, more evidence has appeared in the literature in the last few months on this association. A recent study found that distance travelled is a significant contributing risk factor for pulmonary embolism associated with air travel.2 In this study, the rate of pulmonary embolism was 4.8 cases per 1 000 000 passengers for those travelling more than 10 000 km, and 1.5 cases per 1 000 000 for 5000 km of travel, as compared to 0.01 cases per 1 000 000 among those travelling less than 5000 km.
Symptomless deep vein thrombosis (DVT) might occur in up to 10% of long-haul airline travellers, and the wearing of elastic compression stockings during long-haul air travel is associated with a reduction in symptomless deep vein thrombosis.3
A report from the House of Lords in the United Kingdom entitled Fifth Report: Air Travel and Health has reviewed the evidence available and put forward certain recommendations to prevent deep vein thrombosis based on the baseline risk of the passengers.4
Finally, information for air travellers on ways to prevent venous thromboembolism is abundant on the Internet. The Web site www.airhealth.org has produced an excellent information sheet.5 Travellers can print it off and carry it with them. Some interesting tips on in-flight exercises can also be found from the Web site of Qantas.6
The jury is still out on this association, and we can expect a verdict as more high-quality evidence emerges in the literature.
Padmanabhan Badrinath Clinical Assistant Professor & Epidemiologist Faculty of Medicine & Health Sciences UAE University Al-Ain, United Arab Emirates