The incidence of venous thromboembolism in commercial airline pilots: a cohort study of 2630 pilots. 
Airline pilots may be at increased risk of venous thromboembolism (VTE) because air travel has recently been established as a risk factor for VTE.  The aim of this study was to assess the risk of VTE in a cohort of Dutch airline pilots.  Airline pilots who had been active members of the Dutch aviation society (VNV) were questioned for the occurrence of VTE, presence of risk factors for VTE and number of flight hours per year and rank.  Incidence rates among pilots were compared with those of the general Dutch population and with a population of frequently flying employees of multinational organizations.  A total of 2630 male pilots were followed-up for a total of 20420 person-years (py).  Six venous thromboses were reported, yielding an incidence rate of 0.3 per 1000 py.  The standardized morbidity ratio, comparing these pilots with the general Dutch population adjusted for age, was 0.8.  Compared with the international employee cohort, the standardized morbidity ratio was 0.7 when all employees were included and 0.6 when only the frequently travelling employees were included.  The incidence rate did not increase with number of flight hours per year and did not clearly vary by rank.  We conclude that the risk of VTE is not increased amongst airline pilots.