Travel and the risk of symptomatic venous thromboembolism
Marije ten Wolde(1), Roderik A. Kraaijenhagen(1), Jan Schiereck(2), Petronella J. Hagen(3), Joost J. Mathijssen(1), Melvin R. Mac Gillavry(4, 5), Maria M.W. Koopman(1), Harry R. Büller(1)
(1)Department of Vascular Medicine, Academic Medical Center, Amsterdam,The Netherlands (2)Department of Radiology, University Medical Center, Utrecht,The Netherlands (3)Department of Pulmonary Medicine, Vrije Universiteit Medical Center, Amsterd
Summary Whether long-distance travel and symptomatic venous thromboembolism(VTE) are associated is debated. On the basis ofthe available literature a fair risk estimate cannot be obtained.We estimated an accurate odds ratio for the relationshipbetween recent travelling and symptomatic VTE.From three case-control studies consisting of 788 and 170patients with clinically suspected deep vein thrombosis (DVT)and 989 patients with clinically suspected pulmonary embolism(PE) referred for diagnostic work-up, a pooled odds ratio forthe relation between travel and symptomatic VTE was calculated.Cases were patients in whom the diagnosis was confirmedaccording to a diagnostic management strategy, whereas controlswere patients in whom the diagnosis was excluded andwho had an uneventful clinical follow-up. Patients were seen in the period April 1997 to September 2000. Travel history wasrecorded prior to diagnostic work-up.The pooled odds ratio for the association between any traveland symptomatic venous thromboembolism was 0.9 (95% CI:0.6-1.4).The median travel time was 7 h (quartile range 4 to 10h). Separate analyses performed for different types of transport(plane, car, bus or train) yielded comparable odds ratios. Theanalysis for duration of travelling showed an increased oddsratio of 2.5 (95% CI: 1.0-6.2) in the category of 10-15 h of travelling.This study shows that the average traveller does not have anincreased risk for symptomatic venous thromboembolism. Onlyvery long travelling (more than 10 h) may be associated withvenous thromboembolic disease.