Deep vein thrombosis and air travel: record linkage study

BMJ 2003; 327 doi: (Published 06 November 2003) Cite this as: BMJ 2003;327:1072
  1. C W Kelman, medical adviser (christopher.kelman{at},
  2. M A Kortt, assistant director1,
  3. N G Becker, professor of biostatistics2,
  4. Z Li, postdoctoral fellow2,
  5. JD Mathews, deputy chief medical officer1,
  6. CS Guest, visiting fellow2,
  7. CDJ Holman, chair in public health3
  1. 1Commonwealth Department of Health and Ageing, GPO Box 9848, Canberra, ACT 2601, Australia
  2. 2National Centre for Epidemiology and Population Health, Australian National University,Canberra, ACT 0200
  3. 3School of Population Health, University of Western Australia, Perth, WA 6009, Australia
  1. Correspondence to: C W Kelman
  • Accepted 15 August 2003


Objective To investigate the time relations between long haul air travel and venous thromboembolism.

Design Record linkage study using the case crossover approach.

Setting Western Australia.

Participants 5408 patients admitted to hospital with venous thromboembolism and matched with data for arrivals of international flights during 1981-99.

Results The risk of venous thromboembolism is increased for only two weeks after a long haul flight; 46 Australian citizens and 200 non-Australian citizens had an episode of venous thromboembolism during this so called hazard period. The relative risk during this period for Australian citizens was 4.17 (95% confidence interval, 2.94 to 5.40), with 76% of cases (n = 35)attributable to the preceding flight. A “healthy traveller” effect was observed, particularly for Australian citizens.

Conclusions The annual risk of venous thromboembolism is increased by 12% if one long haul flight is taken yearly. The average risk of death from flight related venous thromboembolism is small compared with that from motor vehicle crashes and injuries at work. The individual risk of death from flight related venous thromboembolism for people with certain pre-existing medical conditions is, however, likely to be greater than the average risk of 1 per 2 million for passengers arriving from a flight. Airlines and health authorities should continue to advise passengers on how to minimise risk.


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