The incidence of venous thromboembolism in low to moderate risk long distance air travellers: The NZATT study

This is the largest prospective study ever undertaken of the incidence of venous thromboembolism (blood clots) in long distance travellers. One thousand subjects were recruited with all subjects travelling for at least 10 hours with a mean duration of air travel of 39 hours. The incidence of blood clots associated with travel was 1.0%. Six of the subjects with blood clots had pre-existing clinical risk factors, two travelled exclusively in business class, six used aspirin and four wore compression stockings.

These results, which were published in The Lancet, confirmed that an association between travel involving multiple long distance air flights and blood clots exists, even in low to moderate risk individuals.  They also suggested that the role of traditional risk factors and prophylactic measures in air traveller's thrombosis requires further investigation.

Recent air travel is a common risk factor for venous thrombo-embolism resulting in hospital admission

This study determined the incidence of air travel in subjects who develop clinically significant venous thromboembolism (blood clots) requiring hospital admission. The medical records of over 500 patients admitted with a DVT or pulmonary embolism to six hospitals in New Zealand were reviewed. The proportion with documented recent air travel was about 10%, which most likely represents an underestimate of the true figure due to the probable incomplete ascertainment of this aspect of the history in a proportion of the medical records. It is considerably higher than that reported previously, probably due to the frequent long distance air travel undertaken by New Zealanders, related in part to our geographic isolation. These findings add weight to the evidence that air traveller's thrombosis is a significant public health problem, particularly in New Zealand.

Prolonged Seated Immobility and VTE

This research programme has identified that prolonged seated immobility at work is a common and important risk factor for venous thromboembolism. The mechanism is similar to that responsible for "travellers thrombosis" in that sitting for prolonged periods of time in cramped conditions results in a reduction in lower limb blood flow, thereby increasing the risk of blood clotting in the veins in the legs (DVT). A pulmonary embolism (PE) occurs when the clot breaks off and travels through the blood stream, and then lodges in the lung. Through a series of studies we have shown that both the total duration of sitting, and the length of time seated at any one time without getting up are important determinants of risk. The occurrence of VTE following prolonged seated immobility has been referred to as the SIT (Seated Immobility Thromboembolism) syndrome.

Oral contraceptive use

The anti-androgen oral contraceptive Diane-35 and Estelle represent an important group of oral contraceptive pills, promoted for women in New Zealand, particularly those with acne. There have preliminary reports that the use of anti-androgen pills might increase the risk of VTE, similar in magnitude to the third generation oral contraceptives, the use of which have been restricted due to this adverse effect.. In a large study involving Wellington and Auckland hospitals we confirmed that the risk of VTE with the anti-androgen oral contraceptive pills was at least as great as the third generation pills.

The incidence of venous thromboembolism in low to moderate risk long distance air travellers: The NZATT study

This is the largest prospective study ever undertaken of the incidence of venous thromboembolism (blood clots) in long distance travellers. One thousand subjects were recruited with all subjects travelling for at least 10 hours with a mean duration of air travel of 39 hours. The incidence of blood clots associated with travel was 1.0%. Six of the subjects with blood clots had pre-existing clinical risk factors, two travelled exclusively in business class, six used aspirin and four wore compression stockings.

These results, which were published in The Lancet, confirmed that an association between travel involving multiple long distance air flights and blood clots exists, even in low to moderate risk individuals.  They also suggested that the role of traditional risk factors and prophylactic measures in air traveller's thrombosis requires further investigation.

Recent air travel is a common risk factor for venous thrombo-embolism resulting in hospital admission

This study determined the incidence of air travel in subjects who develop clinically significant venous thromboembolism (blood clots) requiring hospital admission. The medical records of over 500 patients admitted with a DVT or pulmonary embolism to six hospitals in New Zealand were reviewed. The proportion with documented recent air travel was about 10%, which most likely represents an underestimate of the true figure due to the probable incomplete ascertainment of this aspect of the history in a proportion of the medical records. It is considerably higher than that reported previously, probably due to the frequent long distance air travel undertaken by New Zealanders, related in part to our geographic isolation. These findings add weight to the evidence that air traveller's thrombosis is a significant public health problem, particularly in New Zealand.

Prolonged Seated Immobility and VTE

This research programme has identified that prolonged seated immobility at work is a common and important risk factor for venous thromboembolism. The mechanism is similar to that responsible for "travellers thrombosis" in that sitting for prolonged periods of time in cramped conditions results in a reduction in lower limb blood flow, thereby increasing the risk of blood clotting in the veins in the legs (DVT). A pulmonary embolism (PE) occurs when the clot breaks off and travels through the blood stream, and then lodges in the lung. Through a series of studies we have shown that both the total duration of sitting, and the length of time seated at any one time without getting up are important determinants of risk. The occurrence of VTE following prolonged seated immobility has been referred to as the SIT (Seated Immobility Thromboembolism) syndrome.

Oral contraceptive use

The anti-androgen oral contraceptive Diane-35 and Estelle represent an important group of oral contraceptive pills, promoted for women in New Zealand, particularly those with acne. There have preliminary reports that the use of anti-androgen pills might increase the risk of VTE, similar in magnitude to the third generation oral contraceptives, the use of which have been restricted due to this adverse effect.. In a large study involving Wellington and Auckland hospitals we confirmed that the risk of VTE with the anti-androgen oral contraceptive pills was at least as great as the third generation pills.

The incidence of venous thromboembolism in low to moderate risk long distance air travellers: The NZATT study

This is the largest prospective study ever undertaken of the incidence of venous thromboembolism (blood clots) in long distance travellers. One thousand subjects were recruited with all subjects travelling for at least 10 hours with a mean duration of air travel of 39 hours. The incidence of blood clots associated with travel was 1.0%. Six of the subjects with blood clots had pre-existing clinical risk factors, two travelled exclusively in business class, six used aspirin and four wore compression stockings.

These results, which were published in The Lancet, confirmed that an association between travel involving multiple long distance air flights and blood clots exists, even in low to moderate risk individuals.  They also suggested that the role of traditional risk factors and prophylactic measures in air traveller's thrombosis requires further investigation.

Recent air travel is a common risk factor for venous thrombo-embolism resulting in hospital admission

This study determined the incidence of air travel in subjects who develop clinically significant venous thromboembolism (blood clots) requiring hospital admission. The medical records of over 500 patients admitted with a DVT or pulmonary embolism to six hospitals in New Zealand were reviewed. The proportion with documented recent air travel was about 10%, which most likely represents an underestimate of the true figure due to the probable incomplete ascertainment of this aspect of the history in a proportion of the medical records. It is considerably higher than that reported previously, probably due to the frequent long distance air travel undertaken by New Zealanders, related in part to our geographic isolation. These findings add weight to the evidence that air traveller's thrombosis is a significant public health problem, particularly in New Zealand.

Prolonged Seated Immobility and VTE

This research programme has identified that prolonged seated immobility at work is a common and important risk factor for venous thromboembolism. The mechanism is similar to that responsible for "travellers thrombosis" in that sitting for prolonged periods of time in cramped conditions results in a reduction in lower limb blood flow, thereby increasing the risk of blood clotting in the veins in the legs (DVT). A pulmonary embolism (PE) occurs when the clot breaks off and travels through the blood stream, and then lodges in the lung. Through a series of studies we have shown that both the total duration of sitting, and the length of time seated at any one time without getting up are important determinants of risk. The occurrence of VTE following prolonged seated immobility has been referred to as the SIT (Seated Immobility Thromboembolism) syndrome.

Oral contraceptive use

The anti-androgen oral contraceptive Diane-35 and Estelle represent an important group of oral contraceptive pills, promoted for women in New Zealand, particularly those with acne. There have preliminary reports that the use of anti-androgen pills might increase the risk of VTE, similar in magnitude to the third generation oral contraceptives, the use of which have been restricted due to this adverse effect.. In a large study involving Wellington and Auckland hospitals we confirmed that the risk of VTE with the anti-androgen oral contraceptive pills was at least as great as the third generation pills.