Review: wearing graduated compression stockings during air travel reduces the risk of deep venous thromboembolism
Q In the general population, does prophylactic use of graduated compression stockings during air travel reduce the rate of flight related venous thromboembolism?
Medline, EMBASE/Excerpta Medica, Drugs and Pharmacology, CINAHL, Current Contents, ISI Web of Science, Cochrane Library (Issue 1, 2004), bibliographies of relevant articles, hand searches of relevant journals, trial registries (eg, UK National Research Register and Current Controlled Trials at http://www.controlled-trials.com/), and stocking manufacturers (last search March 2004).
Study selection and assessment:
randomised controlled trials (RCTs) that were published in English or Chinese and compared prophylactic use of any type of graduated compression stockings with no prophylaxis or another method, such as aspirin or low molecular weight heparin, for prevention of thromboembolism (documented using ultrasound scan) during air travel in non-hospitalised participants (all age groups regardless of risk of deep venous thrombosis or pre-existing illness). Studies that used a simulated model instead of actual flight were excluded.
objectively documented thromboembolism (deep and superficial venous thrombosis)
9 RCTs (n = 2482) (range of mean age 42–62 y) met the selection criteria. Commercially produced below-the-knee stockings were used in all RCTs. The pressure of stockings ranged from 17–30 mm Hg at the ankle. Participants in the treatment group were advised to put on stockings 2–3 hours or 6–10 hours before departure. The duration of wearing stockings depended on flight duration (7–15 h). Meta-analyses were done using a fixed effects model. The rate of deep venous thrombosis was lower in the stockings group than in the control (no stockings) group (table). The groups did not differ for rates of superficial venous thrombosis (table).
In the general population, prophylactic use of graduated compression stockings during air travel reduces the rate of flight related deep venous thromboembolism.
- Susan Campbell, RN, MSc
Current evidence shows that a link may exist between air travel and the development of venous thrombosis.1 A systematic review by Adi et al2 found some evidence to suggest that flights lasting ⩾8 hours can increase the risk of deep venous thrombosis if additional risk factors, such as older age, obesity, recent injury or surgery, previous thrombosis, venous insufficiency, malignancy, hormonal therapies or pregnancy, are present.
The current review by Hsieh and Lee is important because it assesses the evidence for using graduated compression stockings for preventing deep venous thrombosis at a time when air travel and long flights are increasing. The review showed that the use of below-the-knee graduated compression stockings decreased the occurrence of deep venous thrombosis in long distance air travellers. However, 2 minor flaws may limit inferences from the results. Firstly, outcome assessors were not blinded to group allocation, which can potentially introduce bias because diagnosis by ultrasound involves a subjective element. Secondly, all participants were informed of other preventive measures such as exercise, standing, and stretching. Thus, the actual effect of stockings alone remains unclear, although the benefit of adding stockings to the other measures is quite clear.
The findings of the review are relevant to nurses in primary care, who may provide advice to air travellers. Patients who are at high risk of deep venous thrombosis should be advised to wear graduated compression stockings that are properly sized and fitted. It is noteworthy that there are no internationally agreed upon standards for stocking pressures. Therefore, care is needed to ensure that the correct pressure is advised, depending on the country of manufacture. Patients should also be advised about other preventive measures such as aspirin and, during the flight, moving often, stretching, drinking water regularly, and avoiding restricting leg movement with baggage under the seat.
The findings also suggest the need for further research to assess whether graduated compression stockings have benefits for other risk groups and the costs and benefits of other preventive measures such as aspirin.
For correspondence: Dr F P Lee, Department of Nursing, Fooyin University, Kaohsuing, Taiwan.
Source of funding: not stated.