Air travel and fatal pulmonary embolism

Abstract

Although long-distance air travel is commonly regarded as a risk factor for venous thromboembolism, the risk of clinically important events has not been well defined. We estimated the absolute risk of dying from pulmonary embolism following long-distance air travel in a national population-based descriptive study of 121 men and women who were aged 15-59 years (the age range in which the majority of international arrivals are found) and whose underlying cause of death was certified as codes 415.1, 451, or 453 of the International Classification of Diseases (ninth revision). Eleven cases had undertaken long-distance air travel in the four weeks before the onset of the fatal episode. The estimated risks of fatal pulmonary embolism following a flight of at least three hours' duration were 0.5 (95% CI 0.2-1.2) and 0.6 (95% CI 0.2-1.4) per million arrivals for overseas visitors and New Zealand residents, respectively. For air travel of more than eight hours' duration, the risk in New Zealand residents was 1.3 (95% CI 0.4-3.0) per million arrivals. We also conducted a case-control study based on those cases who were normally resident in New Zealand and registered on the electoral roll (n = 99). For each case, four controls matched for sex, age, and electorate, were randomly selected from the electoral roll. In the key analysis (based on 88 cases and 334 controls), the adjusted odds ratio for travellers who had flown for more than eight hours was 7.9 (95% CI 1.1-55.1) compared with those who did not undertake a long-distance flight. Long-distance air travellers have a higher risk of dying from pulmonary embolism than non-travellers, but the absolute risk in people aged 15-59 years appears to be very small.