Graduated compression stockings to prevent venous thromboembolism in hospital: evidence from patients with acute stroke.

Pulmonary embolism is the most common preventable cause of death in hospital patients and prevention of venous thromboembolism (VTE) is cost-saving in high-risk patients. Low-dose anticoagulation is very effective at preventing VTE but increases bleeding. Graduated compression stockings and intermittent pneumatic compression devices are also used to prevent VTE and do not increase bleeding, which makes their use appealing in patients who cannot tolerate bleeding, such as patients with acute stroke. Studies that evaluated mechanical methods of preventing VTE were small and mainly used asymptomatic deep vein thrombosis (DVT), detected using screening tests, as the study outcome. The recently published CLOTS Trial 1 (Clots in Legs Or sTockings after Stroke) compared thigh-level compression stockings with no stockings in about 2500 patients with stroke and immobility, and found that thigh-level stockings were not effective. Indirectly, the findings of this study question the ability of stockings to prevent VTE in other patient groups, including those after surgery. CLOTS 1 compared thigh-level and below-knee stockings in about 3000 patients with acute stroke. Given that thigh-level stockings were ineffective in CLOTS 1, it is surprising that they were more effective than below-knee stockings in CLOTS Trial 2. A possible explanation is that below-knee stockings increase DVT, although this seems unlikely. CLOTS 1 and CLOTS 2 question whether graduated compression stockings prevent VTE and suggest the need for further trials evaluating their efficacy in medical and surgical patients.