Stephan Moll, MD writes… Interesting study: Are commercial airline pilots at increased risk of venous thromboembolism (VTE) [ref 1]? One might think so, as air travel is an established, although only weak, risk factor for VTE [ref 2,3]. This study found, however, that the risk of VTE is NOT increased in airline pilots.
Study design: This study asked commercial airline pilots in Holland per questionnaire whether they had had a VTE, their risk factors for VTE, and the number of flight hours per year. The rate of VTE was compared to the general Dutch population and to a population of frequently flying employees of multinational organizations.
Results: 76 % of the pilots who had been sent the questionnaire responded, so that 2,630 pilots were included in the study. Six VTE were reported, yielding an incidence rate of 0.3/1000 patient-years. This incidence rate was slightly lower than in the general population and lower than in a population of frequently flying employees of international organizations. The incidence rate did not increase with number of flight hours per year.
Conclusion: This study found that the risk of VTE is not increased amongst airline pilots.
Comment: While this finding at first seems surprising, as airline travel is a known risk factor for VTE, the authors list several reasons why such a low rate of VTE in their airline pilots may have been found: (a) pilots are typically quite healthy (and more healthy than the general population), (b) pilots are probably less immobilized and have less cramped seating conditions than passengers, (c) pilots who were sent the questionnaire may have been reluctant to confirm that they had had a VTE for fear of professional consequences. Nevertheless, it seems like a fair conclusion that the risk of VTE in commercial pilots is low.
- Kuipers S et al. The incidence of venous thromboembolism in commercial airline pilots: a cohort study of 2630 pilots. J Thromb Haemost 2014,Jun 9.
- Cannegieter SC et al. Travel-related venous thrombosis: results from a large population-based case control study (MEGA study). PLoS Med. 2006;3:e307.
- Chandra D et al. Meta-analysis: travel and risk for venous thromboembolism. Ann Intern Med 2009;151:180-90.