Compression stockings for preventing deep vein thrombosis in airline passengers

Background Air travel might increase the risk of deep vein thrombosis (DVT). It has been suggested that wearing compression stockings might reduce this risk. Objectives To assess the effects of wearing compression stockings versus not wearing them among people travelling on flights lasting at least four hours. Search strategy We searched the Cochrane Peripheral Vascular Diseases Group's Specialized Register (January 2006), the Cochrane Central Register of Controlled Trials (CENTRAL) (in The Cochrane Library, Issue 4, 2005), MEDLINE (January 1966 to November 2005), EMBASE (January 1980 to December 2005) and several other electronic or grey literature sources, detailed in full in the review. The most recent searches were done in January 2006. Selection criteria Randomized trials of compression stockings versus no stockings in passengers on flights lasting at least four hours. Trials in which passengers wore a stocking on one leg but not the other, or those comparing stockings and another intervention were also eligible. Data collection and analysis At least two authors independently assessed the quality of each study and extracted data. We sought additional information from trialists. Main results Ten randomized trials (n = 2856) were included; nine (n = 2821) compared wearing stockings on both legs versus not wearing them, and one (n = 35) compared wearing a stocking on one leg for the outbound flight and on the other leg on the return flight. Of the nine trials, seven included people judged to be at low or medium risk (n = 1548) and two included high risk participants (n = 1273). All flights lasted at least seven hours. Fifty of 2637 participants with follow-up data available in the trials of wearing stockings on both legs had a symptomless DVT; three wore stockings, 47 did not (odds ratio 0.10, 95% confidence interval 0.04 to 0.25, P < 0.00001). There were no symptomless DVTs in three trials. No deaths, pulmonary emboli or symptomatic DVTs were reported. Wearing stockings had a significant impact in reducing oedema (based on six trials). No significant adverse effects were reported. Authors' conclusions Airline passengers similar to those in this review can expect a substantial reduction in the incidence of symptomless DVT and leg oedema if they wear compression stockings. We cannot assess the effect of wearing stockings on death, pulmonary embolus or symptomatic DVT because no such events occurred in these trials. Randomized trials to assess these outcomes would need to include a very large number of people.