Air Travel, Prothrombotic Mutations and Venous Thrombosis: The MEGA Study

Reviewer: Walter F. Sall, MD
The Abramson Cancer Center of the University of Pennsylvania
Ultima Vez Modificado: 10 de diciembre del 2001

Share article

Presenter: Frits R. Rosendaal
Presenter's Affiliation: Leiden University Medical Center, Leiden, Netherlands
Type of Session: Scientific


  • Contradictory reports on air travel and deep venous thrombosis (DVT) risk have documented relative risk varying from 0 to 4.
  • Increasing public awareness of mortalities resulting from PE following extended airline flights makes further study of this issue warranted.
  • The Multiple Environmental and Genetic Assessment of risk factors for venous thrombosis (MEGA) study is a case control study that currently has 829 cases and 829 controls enrolled. In this study, travel history with respect to DVT or PE risk was assessed

    Materials and Methods

  • Of the 829 enrolled cases, 465 had DVT while 341 had PE.
  • Cases were < 70 years of age. Controls were spouses or partners.
  • All patients were questioned about their travel history in the 3 months prior to their thrombotic event.
  • DNA samples were extracted for analysis of genetic risk factors including Factor V Leiden and prothrombin 20210A.


  • 30% of thrombotic events occurred within one week of travel.
  • RR of >4 hours of air travel was 6 compared to controls.
  • The presence of genetic risk factors alone led to a RR of 3. The combination of a genetic risk factor and airplane travel led to a 13-fold increase in RR.
  • The absolute risk of thrombotic event in a nine week follow-up period was 1:6000 for non-travelers without genetic risk factors, 1:1500 for plane travellers without risk factors and 1:500 for plane travellers with risk factors.

    Author's Conclusions

  • Recent plane travel does carry an increased relative risk of thrombosis for flights longer than 4 hours.
  • Genetic risk factors and plane travel appear to have a synergistic effect in causing DVT or PE.
  • Non-airplane travel greater than 4 hours carries only a 2-fold relative risk of thrombotic event.

    Clinical/Scientific Implications
    This case control study provides additional evidence supporting the role of immobility during airline travel as a risk factor for DVT/PE. Further study of behavioral modification (exercise), use of pressure stockings or seat size are needed to more precisely define who is at risk from airline flight. Currently a WHO Global Hazards of Travel study is underway which should shed more light on these issues.

    Oncolink's ASH Coverage made possible by an unrestricted Educational Grant from Amgen.

    Indoor Air Laws Up Adoption of Smokefree-Home Policy

    Nov 10, 2011 - Clean indoor air laws are associated with increased adoption of smokefree-home policies; and complete home smoking bans more than tripled among U.S. households from 1992/1993 to 2006/2007, according to two studies published online Nov. 8 in the American Journal of Preventive Medicine.

  • I Wish You Knew

    How cancer patients have changed my life

    View More

    Blogs and Web Chats

    OncoLink Blogs give our readers a chance to react to and comment on key cancer news topics and provides a forum for OncoLink Experts and readers to share opinions and learn from each other.

    OncoLink OncoPilot

    Frente a un nuevo diagnóstico de cáncer o de cambiar el curso de su tratamiento actual? Deje que nuestro personal de enfermería cáncer que ayudan a pasar!

    Más información