Benefits in NNT
9
1 in 9 were helped (DVT prevented)
Elastic Stockings Plus Medical Therapy for Deep Vein Thrombosis Prevention After Surgery
9 for DVT prevention
Harms in NNT
An unknown number were harmed (patient discomfort)
View As:
Efficacy Endpoints
Deep Vein Thrombosis (DVT)
Harm Endpoints
Patient Discomfort
Narrative
It 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. (This summary, examining the impact of stockings when added to antithrombotic medication is an accompaniment our summary of the impact of stockings without medication, drawn from the same source review).
The Cochrane review identified 10 randomized control trials (n=1248) comparing treatment with GCS as an adjunct to medical therapy (heparin or aspirin) for DVT prophylaxis among surgical patients. The incidence went from 16% in the control group to 4% in the treatment group, with an NNT of 9 (based on an Odds Ratio of 0.25, control event rate of 16%).
The authors conclude that graduated compression stockings (GCS) are an inexpensive and noninvasive means by which DVTs can be prevented.
The Cochrane review identified 10 randomized control trials (n=1248) comparing treatment with GCS as an adjunct to medical therapy (heparin or aspirin) for DVT prophylaxis among surgical patients. The incidence went from 16% in the control group to 4% in the treatment group, with an NNT of 9 (based on an Odds Ratio of 0.25, control event rate of 16%).
The authors conclude that graduated compression stockings (GCS) are an inexpensive and noninvasive means by which DVTs can be prevented.
Caveats
The 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 but one 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.
All but one 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.
Published/Updated
December 9, 2011