Do medical patients need to receive pharmacologic prophylaxis for the prevention of venous thromboembolism?

Acutely ill medical patients with reduced mobility are at increased risk of venous thromboembolism, which can occur during hospitalization or after discharge. A number of clinical trials and meta-analyses have shown that pharmacologic prophylaxis with anticoagulant drugs in these patients significantly reduces the risk of fatal pulmonary embolism as compared to placebo or no treatment, without significant increase in the risk of major bleeding. Thus, the use of anticoagulant prophylaxis is recommended for all high risk medical patients during hospitalization. To identify these high risk patients, clinicians may use the inclusion criteria applied in the trials, with a selection that is mostly qualitative, or risk assessment models, with a selection that is both qualitative and quantitative. With both approaches, about 40 % of medical patients would be at increased risk of venous thrombosis. Because in the real world medical patients tend to be much older and with more comorbidities than in clinical trials, patient selection needs to also take into account risk factors for bleeding. Among others, estimation of creatinine clearance appears to be particularly important to prevent excessive exposure to anticoagulant drugs. Finally, although the risk of venous thrombosis may persist in some patients after hospital discharge, clinical trials assessing extended prophylaxis in this setting have failed to show a convincing clinical benefit with this approach.