Apixaban versus enoxaparin for thromboprophylaxis after hip replacement.

BACKGROUND: There are various regimens for thromboprophylaxis after hip replacement. Low-molecular-weight heparins such as enoxaparin predominantly inhibit factor Xa but also inhibit thrombin to some degree. Orally active, specific factor Xa inhibitors such as apixaban may provide effective thromboprophylaxis with a lower risk of bleeding and improved ease of use. METHODS: In this double-blind, double-dummy study, we randomly assigned 5407 patients undergoing total hip replacement to receive apixaban at a dose of 2.5 mg orally twice daily or enoxaparin at a dose of 40 mg subcutaneously every 24 hours. Apixaban therapy was initiated 12 to 24 hours after closure of the surgical wound; enoxaparin therapy was initiated 12 hours before surgery. Prophylaxis was continued for 35 days after surgery, followed by bilateral venographic studies. The primary efficacy outcome was the composite of asymptomatic or symptomatic deep-vein thrombosis, nonfatal pulmonary embolism, or death from any cause during the treatment period. Patients were followed for an additional 60 days after the last intended dose of study medication. RESULTS: A total of 1949 patients in the apixaban group (72.0%) and 1917 patients in the enoxaparin group (71.0%) could be evaluated for the primary efficacy analysis. The primary efficacy outcome occurred in 27 patients in the apixaban group (1.4%) and in 74 patients in the enoxaparin group (3.9%) (relative risk with apixaban, 0.36; 95% confidence interval [CI], 0.22 to 0.54; P<0.001 for both noninferiority and superiority; absolute risk reduction, 2.5 percentage points; 95% CI, 1.5 to 3.5). The composite outcome of major and clinically relevant nonmajor bleeding occurred in 129 of 2673 patients assigned to apixaban (4.8%) and 134 of 2659 assigned to enoxaparin (5.0%) (absolute difference in risk, -0.2 percentage points; 95% CI, -1.4 to 1.0). CONCLUSIONS: Among patients undergoing hip replacement, thromboprophylaxis with apixaban, as compared with enoxaparin, was associated with lower rates of venous thromboembolism, without increased bleeding. (Funded by Bristol-Myers Squibb and Pfizer; ClinicalTrials.gov number, NCT00423319.).

Apixaban or enoxaparin for thromboprophylaxis after knee replacement.

BACKGROUND: The optimal strategy for thromboprophylaxis after major joint replacement has not been established. Low-molecular-weight heparins such as enoxaparin predominantly target factor Xa but to some extent also inhibit thrombin. Apixaban, a specific factor Xa inhibitor, may provide effective thromboprophylaxis with a low risk of bleeding and improved ease of use. METHODS: In a double-blind, double-dummy study, we randomly assigned patients undergoing total knee replacement to receive 2.5 mg of apixaban orally twice daily or 30 mg of enoxaparin subcutaneously every 12 hours. Both medications were started 12 to 24 hours after surgery and continued for 10 to 14 days. Bilateral venography was then performed. The primary efficacy outcome was a composite of asymptomatic and symptomatic deep-vein thrombosis, nonfatal pulmonary embolism, and death from any cause during treatment. Patients were followed for 60 days after anticoagulation therapy was stopped. RESULTS: A total of 3195 patients underwent randomization, with 1599 assigned to the apixaban group and 1596 to the enoxaparin group; 908 subjects were not eligible for the efficacy analysis. The overall rate of primary events was much lower than anticipated. The rate of the primary efficacy outcome was 9.0% with apixaban as compared with 8.8% with enoxaparin (relative risk, 1.02; 95% confidence interval, 0.78 to 1.32). The composite incidence of major bleeding and clinically relevant nonmajor bleeding was 2.9% with apixaban and 4.3% with enoxaparin (P=0.03). CONCLUSIONS: As compared with enoxaparin for efficacy of thromboprophylaxis after knee replacement, apixaban did not meet the prespecified statistical criteria for noninferiority, but its use was associated with lower rates of clinically relevant bleeding and it had a similar adverse-event profile. (ClinicalTrials.gov number, NCT00371683.)

Apixaban versus enoxaparin for thromboprophylaxis after knee replacement (ADVANCE-2): a randomised double-blind trial.

BACKGROUND: Low-molecular-weight heparins such as enoxaparin are preferred for prevention of venous thromboembolism after major joint replacement. Apixaban, an orally active factor Xa inhibitor, might be as effective, have lower bleeding risk, and be easier to use than is enoxaparin. We assessed efficacy and safety of these drugs after elective total knee replacement. METHODS: In ADVANCE-2, a multicentre, randomised, double-blind phase 3 study, patients undergoing elective unilateral or bilateral total knee replacement were randomly allocated through an interactive central telephone system to receive oral apixaban 2.5 mg twice daily (n=1528) or subcutaneous enoxaparin 40 mg once daily (1529). The randomisation schedule was generated by the Bristol-Myers Squibb randomisation centre and stratified by study site and by unilateral or bilateral surgery with a block size of four. Investigators, patients, statisticians, adjudicators, and steering committee were masked to allocation. Apixaban was started 12-24 h after wound closure and enoxaparin 12 h before surgery; both drugs were continued for 10-14 days, when bilateral ascending venography was scheduled. Primary outcome was the composite of asymptomatic and symptomatic deep vein thrombosis, non-fatal pulmonary embolism, and all-cause death during treatment. The statistical plan required non-inferiority of apixaban before testing for superiority; analysis was by intention to treat for non-inferiority testing. The study is registered at ClinicalTrials.gov, number NCT00452530. FINDINGS: 1973 of 3057 patients allocated to treatment (1528 apixaban, 1529 enoxaparin) were eligible for primary efficacy analysis. The primary outcome was reported in 147 (15%) of 976 apixaban patients and 243 (24%) of 997 enoxaparin patients (relative risk 0.62 [95% CI 0.51-0.74]; p<0.0001; absolute risk reduction 9.3% [5.8-12.7]). Major or clinically relevant non-major bleeding occurred in 53 (4%) of 1501 patients receiving apixaban and 72 (5%) of 1508 treated with enoxaparin (p=0.09). INTERPRETATION: Apixaban 2.5 mg twice daily, starting on the morning after total knee replacement, offers a convenient and more effective orally administered alternative to 40 mg per day enoxaparin, without increased bleeding. FUNDING: Bristol-Myers Squibb; Pfizer.

Neurological outcomes in patients with ischemic stroke receiving enoxaparin or heparin for venous thromboembolism prophylaxis: subanalysis of the Prevention of VTE after Acute Ischemic Stroke with LMWH (PREVAIL) study.

BACKGROUND AND PURPOSE: The Prevention of VTE after Acute Ischemic Stroke with LMWH (PREVAIL) study demonstrated that enoxaparin was superior to unfractionated heparin (UFH) in preventing venous thromboembolism in patients with ischemic stroke and was associated with a small but statistically significant increase in extracranial hemorrhage rates. In this PREVAIL subanalysis, we evaluate the long-term neurological outcomes associated with the use of enoxaparin compared with UFH. We also determine predictors of stroke progression. METHODS: Acute ischemic stroke patients aged >or=18 years, who could not walk unassisted, were randomized to receive enoxaparin (40 mg once daily) or UFH (5000 U every 12 hours) for 10 days. Patients were stratified according to baseline stroke severity using the National Institutes of Health Stroke Scale score. End points for this analysis included stroke progression (>or=4-point increase in National Institutes of Health Stroke Scale score), neurological outcomes up to 3 months postrandomization (assessed using National Institutes of Health Stroke Scale score and modified Rankin Scale score), and incidence of intracranial hemorrhage. RESULTS: Stroke progression occurred in 45 of 877 (5.1%) patients in the enoxaparin group and 42 of 872 (4.8%) of those receiving UFH. Similar improvements in National Institutes of Health Stroke Scale and modified Rankin Scale scores were observed in both groups over the 90-day follow-up period. Incidence of intracranial hemorrhage was comparable between groups (20 of 877 [2.3%] and 22 of 872 [2.5%] in enoxaparin and UFH groups, respectively). Baseline National Institutes of Health Stroke Scale score, hyperlipidemia, and Hispanic ethnicity were independent predictors of stroke progression. CONCLUSIONS: The clinical benefits associated with use of enoxaparin for venous thromboembolism prophylaxis in patients with acute ischemic stroke are not associated with poorer long-term neurological outcomes or increased rates of symptomatic intracranial hemorrhage compared with UFH.

The efficacy and safety of enoxaparin versus unfractionated heparin for the prevention of venous thromboembolism after acute ischaemic stroke (PREVAIL Study): an open-label randomised comparison.

BACKGROUND: Venous thromboembolism prophylaxis with low molecular weight heparin or unfractionated heparin is recommended in acute ischaemic stroke, but which regimen provides optimum treatment is uncertain. We aimed to compare the efficacy and safety of enoxaparin with that of unfractionated heparin for patients with stroke. METHODS: 1762 patients with acute ischaemic stroke who were unable to walk unassisted were randomly assigned within 48 h of symptoms to receive either enoxaparin 40 mg subcutaneously once daily or unfractionated heparin 5000 U subcutaneously every 12 h for 10 days (range 6-14). Patients were stratified by National Institutes of Health Stroke Scale (NIHSS) score (severe stroke > or =14, less severe stroke <14). The primary efficacy endpoint was the composite of symptomatic or asymptomatic deep vein thrombosis, symptomatic pulmonary embolism, or fatal pulmonary embolism. Primary safety endpoints were symptomatic intracranial haemorrhage, major extracranial haemorrhage, and all-cause mortality. This study is registered with ClinicalTrials.gov, number NCT00077805. FINDINGS: In the efficacy population (ie, one or more dose received, presence of deep vein thrombosis or pulmonary embolism, or assessment for venous thromboembolism), enoxaparin (n=666) and unfractionated heparin (669) were given for 10.5 days (SD 3.2). Enoxaparin reduced the risk of venous thromboembolism by 43% compared with unfractionated heparin (68 [10%] vs 121 [18%]; relative risk 0.57, 95% CI 0.44-0.76, p=0.0001; difference -7.9%, -11.6 to -4.2); this reduction was consistent for patients with an NIHSS score of 14 or more (26 [16%] vs 52 [30%]; p=0.0036) or less than 14 (42 [8%] vs 69 [14%]; p=0.0044). The occurrence of any bleeding was similar with enoxaparin (69 [8%]) or unfractionated heparin (71 [8%]; p=0.83). The frequency of the composite of symptomatic intracranial and major extracranial haemorrhage was small and closely similar between groups (enoxaparin 11 [1%] vs unfractionated heparin 6 [1%]; p=0.23). We noted no difference for symptomatic intracranial haemorrhage between groups (4 [1%] vs 6 [1%], respectively; p=0.55); the rate of major extracranial bleeding was higher with enoxaparin than with unfractionated heparin (7 [1%] vs 0; p=0.015). INTERPRETATION: Our results suggest that for patients with acute ischaemic stroke, enoxaparin is preferable to unfractionated heparin for venous thromboembolism prophylaxis in view of its better clinical benefits to risk ratio and convenience of once daily administration.

Prevention of venous thromboembolism: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition).

This article discusses the prevention of venous thromboembolism (VTE) and is part of the Antithrombotic and Thrombolytic Therapy: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Grade 1 recommendations are strong and indicate that the benefits do or do not outweigh risks, burden, and costs. Grade 2 suggestions imply that individual patient values may lead to different choices (for a full discussion of the grading, see the "Grades of Recommendation" chapter by Guyatt et al). Among the key recommendations in this chapter are the following: we recommend that every hospital develop a formal strategy that addresses the prevention of VTE (Grade 1A). We recommend against the use of aspirin alone as thromboprophylaxis for any patient group (Grade 1A), and we recommend that mechanical methods of thromboprophylaxis be used primarily for patients at high bleeding risk (Grade 1A) or possibly as an adjunct to anticoagulant thromboprophylaxis (Grade 2A). For patients undergoing major general surgery, we recommend thromboprophylaxis with a low-molecular-weight heparin (LMWH), low-dose unfractionated heparin (LDUH), or fondaparinux (each Grade 1A). We recommend routine thromboprophylaxis for all patients undergoing major gynecologic surgery or major, open urologic procedures (Grade 1A for both groups), with LMWH, LDUH, fondaparinux, or intermittent pneumatic compression (IPC). For patients undergoing elective hip or knee arthroplasty, we recommend one of the following three anticoagulant agents: LMWH, fondaparinux, or a vitamin K antagonist (VKA); international normalized ratio (INR) target, 2.5; range, 2.0 to 3.0 (each Grade 1A). For patients undergoing hip fracture surgery (HFS), we recommend the routine use of fondaparinux (Grade 1A), LMWH (Grade 1B), a VKA (target INR, 2.5; range, 2.0 to 3.0) [Grade 1B], or LDUH (Grade 1B). We recommend that patients undergoing hip or knee arthroplasty or HFS receive thromboprophylaxis for a minimum of 10 days (Grade 1A); for hip arthroplasty and HFS, we recommend continuing thromboprophylaxis > 10 days and up to 35 days (Grade 1A). We recommend that all major trauma and all spinal cord injury (SCI) patients receive thromboprophylaxis (Grade 1A). In patients admitted to hospital with an acute medical illness, we recommend thromboprophylaxis with LMWH, LDUH, or fondaparinux (each Grade 1A). We recommend that, on admission to the ICU, all patients be assessed for their risk of VTE, and that most receive thromboprophylaxis (Grade 1A).

Long term platelet responses to Helicobacter pylori eradication in Canadian patients with immune thrombocytopenic purpura.

This prospective Canadian pilot study assesses the platelet response rate in H. pylori positive and negative patients and evaluates potential mechanisms to explain response. Patients with ITP received H. pylori eradication therapy and platelet counts at day 56 were used to assess response. Gastric permeability, stool H. pylori antigen and serum CagA anti-body were done at baseline and at day 60. Twenty-two patients were enrolled with an overall response rate of 27% (6/22). The prevalence of H. pylori was 18% (4/22). Seventy-five percent of the H. pylori positive patients (3/4) achieved a response compared to 17% (3/18) of the H. pylori negative patients (P < 0.05). Seventy-five percent of complete responders have demonstrated long-term ongoing responses at 48 months of follow-up. A trend towards lower post-eradication gastric permeability in responders was seen. Although the prevalence of H. pylori is low, H. pylori positive Canadian patients with ITP may benefit from a trial of H. pylori eradication therapy as a safe and effective means to achieve long term platelet response.

Prevention of venous thromboembolism after ischemic stroke.

PURPOSE OF REVIEW: Venous thromboembolism is an important cause of morbidity and mortality after stroke. Its potential for prevention is substantial with the use of antithrombotic agents, but there is no agreement on the relative advantages and disadvantages of various available prophylactic drugs. There have been recent publications that clarify some of these issues. RECENT FINDINGS: Data from recently published controlled clinical trials have added to our understanding of the risk-benefit ratio of the two most commonly used antithrombotics: unfractionated heparin and low-molecular-weight heparins. These data suggest that the low-molecular-weight heparin enoxaparin has a superior clinical profile in comparison with unfractionated heparin. SUMMARY: Antithrombotic agents are the mainstay in the prevention of venous thromboembolism after stroke. The highly effective unfractionated heparin and low-molecular-weight heparins may have a different clinical profile that could have a substantial impact in clinical practice.

A randomized, controlled trial of the use of pulmonary-artery catheters in high-risk surgical patients.

BACKGROUND: Some observational studies suggest that the use of pulmonary-artery catheters to guide therapy is associated with increased mortality. METHODS: We performed a randomized trial comparing goal-directed therapy guided by a pulmonary-artery catheter with standard care without the use of a pulmonary-artery catheter. The subjects were high-risk patients 60 years of age or older, with American Society of Anesthesiologists (ASA) class III or IV risk, who were scheduled for urgent or elective major surgery, followed by a stay in an intensive care unit. Outcomes were adjudicated by observers who were unaware of the treatment-group assignments. The primary outcome was in-hospital mortality from any cause. RESULTS: Of 3803 eligible patients, 1994 (52.4 percent) underwent randomization. The base-line characteristics of the two treatment groups were similar. A total of 77 of 997 patients who underwent surgery without the use of a pulmonary-artery catheter (7.7 percent) died in the hospital, as compared with 78 of 997 patients in whom a pulmonary-artery catheter was used (7.8 percent)--a difference of 0.1 percentage point (95 percent confidence interval, -2.3 to 2.5). There was a higher rate of pulmonary embolism in the catheter group than in the standard-care group (8 events vs. 0 events, P=0.004). The survival rates at 6 months among patients in the standard-care and catheter groups were 88.1 and 87.4 percent, respectively (difference, -0.7 percentage point [95 percent confidence interval, -3.6 to 2.2]; negative survival differences favor standard care); at 12 months, the rates were 83.9 and 83.0 percent, respectively (difference, -0.9 percentage point [95 percent confidence interval, -4.3 to 2.4]). The median hospital stay was 10 days in each group. CONCLUSIONS: We found no benefit to therapy directed by pulmonary-artery catheter over standard care in elderly, high-risk surgical patients requiring intensive care.

Guidelines on the use of intravenous immune globulin for hematologic conditions.

Canada's per capita use of intravenous immune globulin (IVIG) grew by approximately 115% between 1998 and 2006, making Canada one of the world's highest per capita users of IVIG. It is believed that most of this growth is attributable to off-label usage. To help ensure IVIG use is in keeping with an evidence-based approach to the practice of medicine, the National Advisory Committee on Blood and Blood Products of Canada (NAC) and Canadian Blood Services convened a panel of national experts to develop an evidence-based practice guideline on the use of IVIG for hematologic conditions. The mandate of the expert panel was to review evidence regarding use of IVIG for 18 hematologic conditions and formulate recommendations on IVIG use for each. A panel of 13 clinical experts and 1 expert in practice guideline development met to review the evidence and reach consensus on the recommendations for the use of IVIG. The primary sources used by the panel were 3 recent evidence-based reviews. Recommendations were based on interpretation of the available evidence and where evidence was lacking, consensus of expert clinical opinion. A draft of the practice guideline was circulated to hematologists in Canada for feedback. The results of this process were reviewed by the expert panel, and modifications to the draft guideline were made where appropriate. This practice guideline will provide the NAC with a basis for making recommendations to provincial and territorial health ministries regarding IVIG use management. Specific recommendations for routine use of IVIG were made for 7 conditions including acquired red cell aplasia; acquired hypogammaglobulinemia (secondary to malignancy); fetal-neonatal alloimmune thrombocytopenia; hemolytic disease of the newborn; HIV-associated thrombocytopenia; idiopathic thrombocytopenic purpura; and posttransfusion purpura. Intravenous immune globulin was not recommended for use, except under certain life-threatening circumstances, for 8 conditions including acquired hemophilia; acquired von Willebrand disease; autoimmune hemolytic anemia; autoimmune neutropenia; hemolytic transfusion reaction; hemolytic transfusion reaction associated with sickle cell disease; hemolytic uremic syndrome/thrombotic thrombocytopenic purpura; and viral-associated hemophagocytic syndrome. Intravenous immune globulin was not recommended for 2 conditions (aplastic anemia and hematopoietic stem cell transplantation) and was contraindicated for 1 condition (heparin-induced thrombocytopenia). For most hematologic conditions reviewed by the expert panel, routine use of IVIG was not recommended. Development and dissemination of evidence-based guidelines may help to facilitate appropriate use of IVIG.

Multicenter evaluation of the use of venous thromboembolism prophylaxis in acutely ill medical patients in Canada.

BACKGROUND: Venous thromboembolism (VTE) prophylaxis in acutely ill medical patients has been shown to be safe and effective. Underutilization of this patient safety practice may result in avoidable mortality and morbidity. OBJECTIVES: We aimed to determine the proportion of hospitalized, acutely ill medical patients across Canada who were eligible to receive thromboprophylaxis and to evaluate the frequency, determinants and appropriateness of its use. PATIENTS/METHODS: CURVE is a national, multicenter chart audit of 29 Canadian hospitals. Data were collected on consecutive patients admitted to hospital for an acute medical illness during a defined 3-week study period. Information on demographic and clinical characteristics, risk factors for VTE and bleeding and use of VTE prophylaxis were recorded. The indications for and appropriateness of VTE prophylaxis were assessed using pre-specified criteria based on international consensus guidelines. Multivariable analyses were performed to identify determinants of prophylaxis use. RESULTS: Of the 4124 medical admissions screened over the study period, 1894 patients (46%) were eligible for study inclusion. The most common specified admitting diagnoses were severe infection (28%), COPD exacerbation or respiratory failure (12%), malignancy (9%) and congestive heart failure (8%). Thromboprophylaxis was indicated in 1702 (90%) study patients. Overall, some form of prophylaxis was administered to 23% of all patients. However, only 16% received appropriate thromboprophylaxis. Factors independently associated with greater use of prophylaxis included internist (vs. other specialty) as attending physician (OR 1.33, 95% confidence interval (CI) [1.03, 1.71]), university-associated (vs. community) hospital (OR 1.46, 95% CI [1.03, 2.07]), immobilization (per day) (OR 1.60, 95% CI [1.45, 1.77]), presence of >or=1 VTE risk factors (OR=1.78, 95% CI [1.35, 2.34]) and duration of hospitalization (per day of stay) (OR 1.05, 95% CI [1.03, 1.07]), however, use of prophylaxis was unacceptably low in all groups. Patients with cancer had a significantly reduced likelihood of receiving prophylaxis (OR=0.40, 95% CI [0.24, 0.68]). Presence of risk factors for bleeding did not influence the use or choice of prophylaxis. CONCLUSION: Most patients hospitalized for medical illness had indications for thromboprophylaxis, yet only 16% received appropriate prophylaxis. Efforts should be made to elucidate the reasons that underlie the very low rate of thromboprophylaxis in medical patients and to develop and test strategies to improve implementation of this patient safety practice.

Vitamin K antagonists and direct thrombin inhibitors: present and future.

Warfarin and related compounds are efficacious and safe in a variety of clinical thrombotic disorders; however, these drugs have a narrow therapeutic window, whereby inadequate therapy is associated with an increased thrombotic risk and overanticoagulation is associated with bleeding. Therefore, attempts have been made to develop alternatives to warfarin. Ximelagatran, an oral direct thrombin inhibitor, has been shown to be as efficacious and safe as warfarin for the prevention and treatment of different thrombotic disorders. This article reviews the pharmacology of the coumarins, the most commonly used vitamin K antagonists, and the practical aspects regarding their use in the management of thrombotic disorders. The future role of the oral direct thrombin inhibitor ximelagatran also is reviewed.

Low-molecular-weight heparin for the treatment of venous thromboembolism in the elderly.

Venous thromboembolism (deep vein thrombosis and/or pulmonary embolism) is a common problem in the elderly population. Indeed, increasing age is a significant risk factor for venous thromboembolism. The treatment of venous thromboembolism in the elderly population presents certain unique problems related to aging, such as decreasing body weight, increasing renal insufficiency and numerous comorbid conditions, which complicate therapy. Treatment of venous thromboembolism in the elderly has been complicated by an increased incidence of bleeding, particularly with the use of warfarin. The risk of bleeding may be substantially reduced by carefully adjusting the warfarin dose to maintain a therapeutic INR and for this purpose anticoagulant management clinics have been shown to be useful. The low-molecular-weight heparins have been shown to be efficacious and safe for the treatment of venous thromboembolism in several clinical trials, including many patients in the older age brackets. Furthermore, these agents can safely be used in the out-of-hospital setting. Long-term use of low-molecular-weight heparin is an alternative to the use of oral anticoagulant therapy, particularly in patients with cancer or recurrent venous thromboembolism.

Oral delivery of heparin: SNAC and related formulations.

Unfractionated heparin is one of the most commonly used pharmacological agents in hospital practice. The use of this agent is inconvenient in that it must be given parenterally. Current research is directed at development of oral antithrombotic agents that will not require laboratory monitoring of the antithrombotic effect. This has stimulated interest in the development of orally active heparin and low-molecular-weight heparin. It has recently been shown that the addition of SNAC [sodium N-(8-(2-hydroxybenzoyl)amino)caprylate] to heparin enables absorption of therapeutic levels of heparin. Studies to date have shown that oral heparin-SNAC is an effective agent for the prevention of venous thromboembolism following total hip replacement, and this should stimulate further studies with this agent.

Prevention of venous thromboembolism: the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy.

This article discusses the prevention of venous thromboembolism (VTE) and is part of the Seventh American College of Chest Physicians Conference on Antithrombotic and Thrombolytic Therapy: Evidence-Based Guidelines. Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh risks, burden, and costs. Grade 2 suggests that individual patients' values may lead to different choices (for a full understanding of the grading see Guyatt et al, CHEST 2004; 126:179S-187S). Among the key recommendations in this chapter are the following. We recommend against the use of aspirin alone as thromboprophylaxis for any patient group (Grade 1A). For moderate-risk general surgery patients, we recommend prophylaxis with low-dose unfractionated heparin (LDUH) (5,000 U bid) or low-molecular-weight heparin (LMWH) [< or = 3,400 U once daily] (both Grade 1A). For higher risk general surgery patients, we recommend thromboprophylaxis with LDUH (5,000 U tid) or LMWH (> 3,400 U daily) [both Grade 1A]. For high-risk general surgery patients with multiple risk factors, we recommend combining pharmacologic methods (LDUH three times daily or LMWH, > 3,400 U daily) with the use of graduated compression stockings and/or intermittent pneumatic compression devices (Grade 1C+). We recommend that thromboprophylaxis be used in all patients undergoing major gynecologic surgery (Grade 1A) or major, open urologic procedures, and we recommend prophylaxis with LDUH two times or three times daily (Grade 1A). For patients undergoing elective total hip or knee arthroplasty, we recommend one of the following three anticoagulant agents: LMWH, fondaparinux, or adjusted-dose vitamin K antagonist (VKA) [international normalized ratio (INR) target, 2.5; range, 2.0 to 3.0] (all Grade 1A). For patients undergoing hip fracture surgery (HFS), we recommend the routine use of fondaparinux (Grade 1A), LMWH (Grade 1C+), VKA (target INR, 2.5; range, 2.0 to 3.0) [Grade 2B], or LDUH (Grade 1B). We recommend that patients undergoing hip or knee arthroplasty, or HFS receive thromboprophylaxis for at least 10 days (Grade 1A). We recommend that all trauma patients with at least one risk factor for VTE receive thromboprophylaxis (Grade 1A). In acutely ill medical patients who have been admitted to the hospital with congestive heart failure or severe respiratory disease, or who are confined to bed and have one or more additional risk factors, we recommend prophylaxis with LDUH (Grade 1A) or LMWH (Grade 1A). We recommend, on admission to the intensive care unit, all patients be assessed for their risk of VTE. Accordingly, most patients should receive thromboprophylaxis (Grade 1A).

Coumarin therapy in thrombosis.

Oral anticoagulants are the most commonly used agents in the long-term prophylaxis and treatment of arterial and venous thrombotic disorders. As new and expanded indications for their use, such as the prevention of recurrent myocardial infarction or the treatment of systemic embolism in atrial fibrillation, are developed, the use of oral anticoagulants is rising. Also, in North America, oral anticoagulants are used commonly for preventing venous thromboembolism following orthopedic surgery. This article reviews the pharmacology of warfarin sodium, the most commonly used oral anticoagulant in North America, and discusses practical aspects of the use of this agent in thrombotic disorder management.