The incidence of venous thromboembolism in commercial airline pilots: a cohort study of 2630 pilots

Abstract

Summary. Background: Airline pilots may be at increased risk of venous thromboembolism (VTE) because air travel has recently been established as a risk factor for VTE. Objectives: The aim of this study was to assess the risk of VTE in a cohort of Dutch airline pilots. Patients/Methods: 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. Results and Conclusions: 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.

Venous thromboembolism risk associated with protracted work- and computer-related seated immobility: A case-control study

“… 16 , 17 In the previous studies, we selected controls from patients presenting to coronary care unit, based on the landmark case-control study on traveller’s thrombosis 8 and recognition of common risk factors for venous thromboembolism and atherosclerosis. 17 , 18 We hypothesised that this coronary care unit group might result in an underestimation of the risk associated with prolonged seated immobility as such patients may be more likely to have a sedentary occupation due to limitations placed on them by their cardiovascular disease. For this reason, we chose a different control group, a ‘healthy’ group presenting to the Emergency Department with upper limb injury in whom there was no clinical suspicion of venous thromboembolism.…”

“…It is possible the selection of controls derived from coronary care unit may be preferable, on the basis that it may be more representative of the population at risk of presentation to hospital with a venous thrombosis. 17 , 18 …”

“… 15 It is unclear why the incidence of venous thromboembolism is not increased in long-haul commercial airline pilots, who are also exposed to prolonged periods of sitting. 18 …”

Immigration, region of origin, and the epidemiology of venous thromboembolism: A population‐based study

“…16 However, two well-conducted studies in captive populations have shown that the absolute IR of VTE does not seem to differ from that in general population. 17,18 Nevertheless, there is a possibility that immigrants might have developed VTE events during this period that would not have been captured, but because of the aforementioned reasons we believe that it is unlikely that a significant number of events were missed. In any case such limitation would apply to all immigrant groups and it would have very little effect on the risk ratios.…”

“…In this regard, although long‐distance travel has been reported to slightly increase the risk of VTE such risk is difficult to measure due to the lack of proper follow‐up in travelers 16. However, two well‐conducted studies in captive populations have shown that the absolute IR of VTE does not seem to differ from that in general population 17, 18. Nevertheless, there is a possibility that immigrants might have developed VTE events during this period that would not have been captured, but because of the aforementioned reasons we believe that it is unlikely that a significant number of events were missed.…”