title: Incidence of air travel-related pulmonary embolism at the Madrid-Barajas airport.
abstract: BACKGROUND
  Prolonged air travel and the associated immobilization are risk factors for venous thromboembolism. The occurrence of pulmonary thromboembolism (PTE) under these circumstances is referred to as economy class syndrome. We assessed the incidence of symptomatic PTE in passengers on long-haul flights arriving at Madrid-Barajas Airport, Madrid, Spain, and the association with the number of flight hours.
  
  
  METHODS
  We retrospectively reviewed cases of PTE among international travelers arriving at Madrid-Barajas Airport between January 1995 and December 2000. Patients presenting with symptoms of deep venous thrombosis but without symptoms of PTE were excluded. Pulmonary thromboembolism was identified using an algorithm of diagnostic tests. The incidence of PTE and the association with flight duration was assessed.
  
  
  RESULTS
  The average number of passengers per year who arrived at the airport on flights originating abroad in the period analyzed was 6 839 222. Sixteen cases of PTE were detected over the 6-year period. All patients with travel-associated PTE had flight durations of greater than 6 hours. The overall incidence of PTE was 0.39 per 1 million passengers (95% confidence interval [CI], 0.20-0.58). On flights that lasted between 6 and 8 hours, the incidence was 0.25 per 1 million passengers (95% CI, 0-0.75), while on flights longer than 8 hours, the incidence was 1.65 per 1 million passengers (95% CI, 0.81-2.49) (P<.001).
  
  
  CONCLUSIONS
  Air travel is a risk factor for PTE, and the incidence of PTE increases with the duration of the air travel. However, the low incidence of PTE among long-distance passengers, similar to that observed in other international airports, does not justify social alarm.
authors.affiliation: Pneumology Department, Ramón y Cajal Hospital, Madrid, Spain.
authors.forename: Esteban
authors.initials: E
authors.lastname: Pérez-Rodríguez
authors.forename: David
authors.initials: D
authors.lastname: Jiménez
authors.forename: Gema
authors.initials: G
authors.lastname: Díaz
authors.forename: Ivan
authors.initials: I
authors.lastname: Pérez-Walton
authors.forename: Manuel
authors.initials: M
authors.lastname: Luque
authors.forename: Carmen
authors.initials: C
authors.lastname: Guillén
authors.forename: Eva
authors.initials: E
authors.lastname: Mañas
authors.forename: Roger D
authors.initials: RD
authors.lastname: Yusen
mesh_terms: D000368:Aged; D000401:Aircraft; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D011655:Pulmonary Embolism / Q000453:epidemiology* / Q000209:etiology / Q000517:prevention & control; D012189:Retrospective Studies; D012307:Risk Factors; D013577:Syndrome; D013997:Time Factors; D014195:Travel; D020246:Venous Thrombosis / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control