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 effects of wearing compression stockings versus not wearing them for preventing DVT in people travelling on flights lasting at least four hours.
SEARCH METHODS: For this update the Cochrane Vascular Information Specialist (CIS) searched the Specialised Register (10 February 2016). In addition, the CIS searched the Cochrane Register of Studies (CENTRAL (2016, Issue 1)).
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. Eleven randomised trials (n = 2906) were included in this review: nine (n = 2821) 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.Fifty 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-quality 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-quality evidence). No deaths, pulmonary emboli or symptomatic DVTs were reported. Wearing stockings had a significant impact in reducing oedema (mean difference (MD) -4.72, 95% CI -4.91 to -4.52; based on six trials; low-quality evidence). A further two trials showed reduced oedema in the stockings group but could not be included in the meta-analysis as they used different methods to measure oedema. No significant adverse effects were reported.
AUTHORS' CONCLUSIONS: There is high-quality evidence that airline passengers similar to those in this review can expect a substantial reduction in the incidence of symptomless DVT and low-quality evidence that leg oedema is reduced if they wear compression stockings. Quality was limited by the way that oedema was measured. There is moderate-quality evidence that superficial vein thrombosis may be reduced if passengers wear compression stockings. We cannot assess the effect 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.
While there was no evidence of benefit for symptomatic DVTs, PEs, or deaths, the article did mention that the study was not adequately powered to demonstrate such an effect. Because this study may be as good as we will get on the issue and since compression stockings are well-tolerated and benign, I believe it reasonable to recommend use of compression stockings, especially in higher-risk patients.
So, airlines will have compression stockings available on long-haul flights and will probably be able to charge more!!! I will discuss this with my patients. I have had quite a few patients with DVTs from flying.
This review provides quality evidence to address a clinically significant question: are compression stockings potentially protective for patients planning long-distance airplane flights? The answer seems to be clear: stockings reduce relative risk for symptomless DVT dramatically in all patient passengers, and reduce absolute risk in high-risk persons substantially. Clinicians could still ask whether the benefits of reducing the risk of symptomless DVT outweigh the burdens of purchasing and wearing compression stockings.
Good description of benefit that could be useful, particularly in high-risk groups. One limitation would be insurance coverage, cost, and any sort of stratification for the large group that has "limited mobility due to bone/joint problems." Lots of patients seen in primary care have some limitation in mobility, but it would be harder to define a group that might benefit from this intervention, such that the therapy would be recommended.
Most important message of this review is the absence of symptomatic PE or DVT in ANY of the ~1400 patients who flew > 4 hrs without compression stockings.
As a hematologist who specializes in thrombosis, I am often asked about the risk for deep-vein thrombosis (DVT) with long flights, and whether wearing of compression stocking reduces this risk. Although this article shows that wearing compression stocking on flights longer than 4 hours reduces the risk for asymptomatic DVT compared with not wearing stockings, the clinical relevance of asymptomatic DVT is uncertain. Moreover, what is not pointed out in this article is that most of the asymptomatic clots were in the calf and diagnosis of calf DVT is less accurate than diagnosis of more proximal DVT. Furthermore, even when calf DVT is objectively diagnosed, there is uncertainty as to whether it requires treatment. Therefore, the findings of this article are somewhat misleading and are not particularly helpful for patient management.
Updated Cochrane review shows high-quality evidence that airline passengers can expect a substantial reduction in the occurrence of symptomless DVT, which means DVT that likely would not have progressed to reach clinical attention, and low-quality evidence that leg swelling is reduced if they wear compression stockings. Authors could not indicate the effect of wearing stockings on death, pulmonary embolism, or symptomatic DVT as such events did not occur in these trials. Randomized trials to assess these outcomes would need to include a very large number of people, and are infeasible. Overall, therefore, little evidence of clinical benefit for stockings used by airplane travelers (and they cost about $35 a pair).
This meta-analysis suggests that wearing flight stockings reduces superficial vein thrombosis of the legs. Although they reduce asymptomatic deep vein thrombosis, we do not know the clinical relevance of this finding.
Not the greatest evidence but something that patients ask a lot about.
The rate of important events is quite low regardless of stocking use, so may not matter much.