The absolute risk of venous thrombosis after air travel: A cohort study of 8,755 employees of international organisations
2007

Risk of Blood Clots After Air Travel

Sample size: 8755 publication 10 minutes Evidence: moderate

Author Information

Author(s): Saskia Kuipers, Suzanne Cannegieter, Saskia Middeldorp, Luc Robyn, Harry R. Büller, Frits R. Rosendaal

Primary Institution: Leiden University Medical Center

Hypothesis

What is the absolute risk of venous thrombosis after air travel?

Conclusion

The risk of symptomatic venous thrombosis after air travel is moderately increased on average, and rises with increasing exposure and in high-risk groups.

Supporting Evidence

  • The study followed 8,755 employees for a total of 38,910 person-years.
  • 53 cases of venous thrombosis were confirmed during the study.
  • The incidence rate of thrombosis was 3.2 per 1,000 person-years after long-haul flights.

Takeaway

Flying can make you more likely to get a blood clot, but it's still pretty rare—about 1 in 4,656 flights might lead to one.

Methodology

A cohort study was conducted among employees of large international companies, tracking symptomatic venous thrombosis linked to air travel exposure.

Potential Biases

Potential bias due to self-reported data and varying response rates among organizations.

Limitations

The study's response rate was 32%, and results may not be generalizable to older or less healthy populations.

Participant Demographics

Mean age of participants was 40 years, with 56% being men.

Statistical Information

P-Value

1/4,656

Confidence Interval

95% CI 1.8–5.6

Statistical Significance

p<0.05

Digital Object Identifier (DOI)

10.1371/journal.pmed.0040290

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