Elastic Stockings for Deep Vein Thrombosis Prevention After Surgery
Benefits in NNT
1 in 7 were helped (DVT prevented)
87% saw no benefit
13% were helped by preventing a DVT
Harms in NNT
An unknown number were harmed (patient discomfort)
An unknown number were harmed by patient discomfort
SourceSachdeva A, Dalton M, Amaragiri SV, Lees T Elastic compression stockings for prevention of deep vein thrombosis(Review). Cochrane Database Syst Rev. 2010 April 18;(7):CD001484
Efficacy EndpointsDeep Vein Thrombosis (DVT)
Harm EndpointsPatient Discomfort
NarrativeIt has long been observed that hospitalized patients are at increased risk for developing a DVT. Venous stasis and lack of mobility are known risk factors for development of venous thromboemboli. It has been hypothesized that graded compression stockings, by compressing superficial veins, cause increased blood flow through the deep veins in the extremities thereby decreasing venous stasis and DVT.
The Cochrane review identified 8 randomized control trials (n=1279) comparing treatment with GCS vs. standard therapy for DVT prophylaxis among surgical patients. The incidence of DVT decreased from 26% in the control group to 13% in the treatment group, with an NNT of 8 (based on an odds ratio of 0.35 and a control event rate of 26%).
CaveatsThe purpose of preventing DVT is to prevent the life threatening or physiologically uncomfortable symptoms of either DVT or pulmonary embolism. The great bulk of the included trials did not measure these outcomes, making it impossible to know if preventing DVTs has an important impact on patient-oriented outcomes. Large, high quality, well-powered trials that closely track both the adverse effects of stockings (discomfort, etc.) and clinically important events related to venous thromboembolism are badly needed.
All of the included trials involved patients undergoing surgical procedures as the reason for their hospitalization, and none of the studies included low risk patients. Consequently, firm conclusions can only be drawn regarding GCS for moderate to high risk surgical patients.
In addition 6 of the 18 trials used the other leg as the control group. It has been hypothesized that compression to one leg could have an adverse effect on the other leg. If true, this could reflect a bias toward the treatment group in these studies. In addition, 10 of the trials included industry funding of some form.
For the time being GCS seem like an inexpensive, low side effect intervention that is a reasonable choice to reduce the presence of imaging-detectable DVT, and we have therefore rated this intervention ‘Green’ (i.e. beneficial), with the caveat that patient-oriented study designs may ultimately challenge or support this conclusion.