Clinical risk factors for venous thrombosis associated with air travel

Background: Recent reports have linked air travel with Venous thrombo-embol ism (VTE). Risk factors and associated features of this link are poorly und erstood. We have accumulated clinical data from a relatively large cohort o f patients with traveler's thrombosis. Methods: A total of 86 patients who developed venous thromboembolism within 28 d of flying were questioned conc erning traveling habits, medical history (including risk factors for VTE) a nd characteristics of the index flight. Results: Of the patients, 72% had a t least one risk factor for VTE (excluding thrombophilia) prior to their fl ight. Of interest, 87% of VTE cases occurred following either a return trip or after an outward journey involving long trips made up of sequential fli ghts. In only two cases could no identifiable risk factor or earlier journe y be found. Duration of flights ranged from 2 to 30 h. Of responders, 38% p resented with chest symptoms; 92% with VTE developed symptoms within 96 h o f their flight. Conclusion: We conclude that the majority of VTE associated with air travel occur in those with identifiable risk factors prior to the ir flight, and that sequential flights may increase this risk.