Long-haul flights and deep vein thrombosis: a significant risk only when additional factors are also present.

To address the association between travel and deep vein thrombosis (DVT) we examined the risk factors for DVT in 568 consecutive patients with suspected DVT attending King's College Hospital in London. No significant link between DVT and long-haul travel was demonstrable in this cohort, with an odds ratio of 1.3 (CI 0.6-2.8). Risk of DVT was only increased in long-haul travellers if one or more additional risk factors were present, with an odds ratio of 3.0 (CI 1.1-8.2). Such individuals may benefit from prophylactic measures to minimize risk.