Low-Molecular-Weight Heparin in Medical Patients

Posted by • December 30th, 2011

Pharmacologic thromboprophylaxis has been proven to reduce the incidence of venous thromboembolism in both  surgical patients and acutely ill medical patients. In surgical patients, thromboprophylaxis has been shown to reduce  the incidence of fatal pulmonary embolism and the rate of death from any cause; in medical patients, studies have  shown that thromboprophylaxis is associated with reductions in the rate of venous thromboembolic events, including  asymptomatic deep-vein thrombosis.

Clinical Pearls

What are the most common adverse effects associated with the use of enoxaparin?

In the study reported in this week’s Journal, major bleeding events during the treatment period and up to 48 hours  after the treatment period were reported in 16 patients in the enoxaparin group (0.4%) and in 11 patients in the placebo group (0.3%) (risk ratio with enoxaparin, 1.4; 95% CI, 0.7 to 3.1; P=0.35). The rates of minor bleeding were  higher in the enoxaparin group than in the placebo group, and the combined rates of all minor or major bleeding  events were higher in the enoxaparin group. The rate of all adverse events was 37.8% in the enoxaparin group and  36.9% in the placebo group. The two groups did not differ significantly with respect to the rate of either serious adverse  events or adverse events leading to death. The rate of adverse events leading to permanent discontinuation of  the study drug was higher in the enoxaparin group than in the placebo group. Enoxaparin use has been associated  with nausea, diarrhea, fever, anemia, thrombocytopenia, and elevated liver function tests.

Table 3. Bleeding Outcomes during the Treatment Period.

In the absence of venous thromboembolism prophylaxis, which one of the following represents the percentage of  patients admitted to a medical service who will develop a deep venous thrombosis?

Venous thromboembolism is an important complication in hospitalized patients. It is estimated that if  thromboprophylaxis is not administered, objectively diagnosed deep-vein thrombosis — with the potential for fatal  pulmonary embolism — will develop in 10 to 20% of medical patients and in 40 to 60% of patients undergoing major orthopedic surgery. A retrospective review of 6833 autopsies showed that 81% of fatal cases of pulmonary embolism  occurred in nonsurgical patients.

Morning Report Questions

Q: What were the primary outcomes in this study of hospitalized acutely ill medical patients treated with enoxaparin  plus compression stockings versus those treated with compression stockings alone?

A: This study did not detect a significant difference in the rate of death from any cause among patients hospitalized for  an acute medical illness when a strategy of pharmacologic prophylaxis in addition to the use of elastic stockings with  graduated compression was compared with the use of elastic stockings with graduated compression alone.

Table 2. Efficacy Outcomes and the Characteristics and Primary Causes of Death.

Q: What do the authors cite as a possible explanation for lack of difference between the use of elastic stockings alone  and elastic stockings plus enoxaparin?

A: One possible explanation provided by the authors is that the use of elastic stockings with graduated compression  alone is effective in preventing venous thromboembolism, thus reducing the frequency of fatal pulmonary embolism.  Although elastic stockings with graduated compression have been shown to be effective in reducing the risk of deep-vein thrombosis in moderate-risk surgical patients and other medical patient populations, the use of stockings  did not prevent the occurrence of deep-vein thrombosis in patients recuperating from severe, disabling stroke who  were participants in the Clots in Legs or Stocking after Stroke trial (CLOTS). Furthermore, the knee-length stockings  used in this study have recently been shown to be less effective than thigh-length stockings for the prevention of  deep-vein thrombosis.

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