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. This is an update of the review first published in 2006. Objectives To assess the eCects of wearing compression stockings versus not wearing them for preventing DVT in people travelling on flights lasting at least four hours. Search methods The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase, CINAHL and AMED databases and World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov trials registers to 1 April 2020. We also checked the bibliographies of relevant studies and reviews identified by the search to check for any additional trials. Selection criteria Randomised 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 Two review authors independently selected trials for inclusion and extracted data. We sought additional information from trialists where necessary. Main results One new study that fulfilled the inclusion criteria was identified for this update. Twelve randomised trials (n = 2918) were included in this review: ten (n = 2833) compared wearing graduated compression stockings on both legs versus not wearing them; one trial (n = 50) compared wearing graduated compression tights versus not wearing them; and one trial (n = 35) compared wearing a graduated compression stocking on one leg for the outbound flight and on the other leg on the return flight. Eight trials included people judged to be at low or medium risk of developing DVT (n = 1598) and two included high-risk participants (n = 1273). All flights had a duration of more than five hours. Ny of 2637 participants with follow-up data available in the trials of wearing compression stockings on both legs had a symptomless DVT; three wore stockings, 47 did not (odds ratio (OR) 0.10, 95% confidence interval (CI) 0.04 to 0.25, P < 0.001; high-certainty evidence). There were no symptomless DVTs in three trials. Sixteen of 1804 people developed superficial vein thrombosis, four wore stockings, 12 did not (OR 0.45, 95% CI 0.18 to 1.13, P = 0.09; moderate-certainty evidence). No deaths, pulmonary emboli or symptomatic DVTs were reported. Wearing stockings had a significant impact in reducing oedema (mean diCerence (MD) -4.72, 95% CI -4.91 to -4.52; based on six trials; lowcertainty evidence). A further three trials showed reduced oedema in the stockings group but could not be included in the meta-analysis as they used diCerent methods to measure oedema. No significant adverse eCects were reported. Authors' conclusions There is high-certainty evidence that airline passengers similar to those in this review can expect a substantial reduction in the incidence of symptomless DVT and low-certainty evidence that leg oedema is reduced if they wear compression stockings. The certainty of the evidence was limited by the way that oedema was measured. There is moderate-certainty evidence that superficial vein thrombosis may be reduced if passengers wear compression stockings. We cannot assess the eCect of wearing stockings on death, pulmonary embolism or symptomatic DVT because no such events occurred in these trials. Randomised trials to assess these outcomes would need to include a very large number of people.