Abstract: We identified 10 RCTs with a total of 2361 participants that evaluated compression therapy. The overall methodological quality of these trials was low. We used only five studies in meta-analysis owing to differences in intervention types and lack of data. Three studies compared elastic compression stockings (pressure of 30 to 40 mmHg at the ankle) versus no intervention. Two studies compared elastic compression stockings (pressure 20 to 40 mmHg) versus placebo stockings. Overall, use of elastic compression stockings led to a clinically significant reduction in the incidence of PTS (risk ratio (RR) 0.62, 95% confidence interval (CI) 0.38 to 1.01; P = 0.05; 1393 participants; 5 studies; low-quality evidence); no reduction in the incidence of severe PTS (RR 0.78, 95% CI 0.53 to 1.15; P = 0.21; 1224 participants; 4 studies; low-quality evidence); and no clear difference in DVT recurrence (RR 0.94, 95% CI 0.69 to 1.28; 1212 participants; 4 studies; P = 0.69; low-quality evidence). We did not pool data on the incidence of pulmonary embolism because this information was poorly reported, but we observed no differences between groups included in individual studies (low-quality evidence). Two studies evaluated effects of compression in the acute phase versus no compression treatment and found no differences in the incidence of PTS (RR 0.76, 95% CI 0.49 to 1.16; P = 0.2; 101 participants). One study reported that thigh-length stockings did not provide better protection against development of PTS than knee-length stockings (RR 0.92, 95% CI 0.66 to 1.28; P = 0.6; 267 participants). Another trial reported that wearing compression stockings for two years seemed to be superior to wearing them for one year in terms of PTS incidence. Two of the 10 included studies described patient satisfaction and quality of life (moderate-quality evidence), using different measurement systems. The first study showed significant improvement in well-being and DVT-related quality of life with compression treatment (P < 0.05) compared with bed rest, and the second study showed no differences in quality of life scores between compression and placebo groups. Four studies poorly reported side effects (low-quality evidence) that included itching, erythema, and other forms of allergic reaction and described no serious adverse events. Compliance with wearing of compression stockings was generally high but varied across studies. Low-quality evidence suggests that elastic compression stockings may reduce the occurrence of PTS after DVT. We downgraded the quality of evidence owing to considerable heterogeneity between studies and lack of or unclear risk of blinding due to clinical assessment scores. No serious adverse effects occurred in these studies. Large randomised controlled trials are needed to confirm these findings because of current lack of high-quality evidence and considerable heterogeneity.

Plain-language summary: We identified 10 randomised controlled trials with a total of 2361 participants that evaluated compression therapy (current until March 2017). We combined five trials to assess our main outcome - PTS. We found that people with DVT who wear elastic compression stockings are less likely to develop PTS, and that compression did not lead to reduced incidence of severe PTS. We found no clear differences in occurrence of pulmonary embolism (blockage of the artery in the lung) nor in reports of recurrent DVT. Compression in the acute phase of DVT compared with "no compression" treatment did not significantly lower PTS incidence. Thigh-length stockings did not provide better protection against development of PTS than knee-length stockings. One trial reported that wearing compression stockings for two years seemed to be superior to wearing them for one year in terms of PTS incidence. Compression treatment did not seem to improve quality of life, except during the first nine days after DVT, but we could draw no real conclusions regarding this outcome. Side effects included itching, erythema, and other forms of allergic reaction. The study investigators reported no serious adverse events and indicated that compliance with use of compression stockings was generally high but varied across studies. Although studies show a reduction in the number of people developing PTS, the quality of evidence is low because of considerable differences between studies and lack of or unclear risk of blinding due to clinical assessment scores. Overall, the included studies were of poor methodological quality.