Proficient and cost-effective approaches for the prevention and treatment of venous thrombosis and thromboembolism

Efficacy and Safety of Tinzaparin Thromboprophylaxis in Lung Cancer Patients with High Thromboembolic Risk: A Prospective, Observational, Single-Center Cohort Study

BACKGROUND

The aim of this study was to record and assess the efficacy and safety ofthromboprophylaxis with an intermediate dose of Tinzaparin in lung cancer patients with high thrombotic risk.

METHODS

This was a non-interventional, single-arm, prospective cohort study of lung cancer patients who received thromboprophylaxis with Tinzaparin 10.000 Anti-Xa IU in 0.5 mL, OD, used in current clinical practice. Enrolled ambulatory patients signed informed consent. Anti-Xa levels were tested.

RESULTS

In total, 140 patients were included in the study, of which 81.4% were males. The histology of the tumor was mainly adenocarcinoma. Lung cancer patients with high thrombotic risk based on tumor, patient, treatment, and laboratory-related factors were enrolled. Only one patient experienced a thrombotic event (0.7%), and 10 patients had bleeding events (7.1%), including only one major event. Anti-Xa levels measured at 10 days and 3 months did not differ significantly between patients who developed hemorrhagic events and those who did not (p = 0.26 and p = 0.32, respectively).

CONCLUSION

Thromboprophylaxis with an intermediate Tinzaparin dose in high thrombotic-risk lung cancer patients is a safe and effective choice for the prevention of VTE.

Vascular Imaging in the Asymptomatic High-risk Cancer Population: A Role for Thrombosis Screening and Therapy Management

OBJECTIVES

We retrospectively examined the venous thromboembolism (VTE) events diagnosed in the Prophylaxis of High-Risk Ambulatory Cancer Patients Study (PHACS), a multi-center randomized trial, to assess the value of screening vascular imaging for the diagnosis of incidental VTE in high-risk cancer patients.

METHODS

A total of 117 asymptomatic cancer patients with a Khorana score ≥3 starting a new systemic chemotherapy regimen were enrolled in a prospective randomized control trial. Patients underwent baseline venous ultrasound (US) of the lower extremities (LEs) and screening contrast-enhanced chest computed tomography (CT). Those without preexisting VTE were then randomized into observation or dalteparin prophylaxis groups and were screened with serial US every 4 weeks for up to 12 weeks and imaged with contrast-enhanced chest CT at 12 weeks. Any additional imaging performed during the study period was also evaluated for VTE.

RESULTS

Baseline prevalence of incidental VTE was 9% (n = 10) with 58% percent of VTEs diagnosed by screening US. Incidence of VTE in the randomized phase of the trial was 16% (n = 16) with 21% (n = 10) of patients in the control arm and 12% (n = 6) of patients in the dalteparin arm developing VTE, a non-significant 9% absolute risk reduction (HR = 0.69, 95% CI 0.23-1.89). Sixty-nine percent of these patients were asymptomatic with 31% of patients diagnosed by screening US.

CONCLUSIONS

Adding screening US to routine oncologic surveillance CT in high-risk ambulatory cancer patients with a Khorana score ≥3 can lead to increased VTE detection, with potential for decreased morbidity, mortality, and health care spending.

Cost-effectiveness of strategies for diagnosing pulmonary embolism among emergency department patients presenting with undifferentiated symptoms

STUDY OBJECTIVE

Symptoms associated with pulmonary embolism can be nonspecific and similar to many competing diagnoses, leading to excessive costly testing and treatment, as well as missed diagnoses. Objective studies are essential for diagnosis. This study evaluates the cost-effectiveness of different diagnostic strategies in an emergency department (ED) for patients presenting with undifferentiated symptoms suggestive of pulmonary embolism.

METHODS

Using a probabilistic decision model, we evaluated the incremental costs and effectiveness (quality-adjusted life-years gained) of 60 testing strategies for 5 patient pretest categories (distinguished by Wells score [high, moderate, or low] and whether deep venous thrombosis is clinically suspected). We performed deterministic and probabilistic sensitivity analyses.

RESULTS

In the base case, for all patient pretest categories, the most cost-effective diagnostic strategy is to use an initial enzyme-linked immunosorbent assay D-dimer test, followed by compression ultrasonography of the lower extremities if the D-dimer is above a specified cutoff. The level of the preferred cutoff varies with the Wells pretest category and whether a deep venous thrombosis is clinically suspected. D-dimer cutoffs higher than the current recommended cutoff were often preferred for patients with even moderate and high Wells categories. Compression ultrasonography accuracy had to decrease below commonly cited levels in the literature before it was not part of a preferred strategy.

CONCLUSION

When pulmonary embolism is suspected in the ED, use of an enzyme-linked immunosorbent assay D-dimer assay, often at cutoffs higher than those currently in use (for patients in whom deep venous thrombosis is not clinically suspected), followed by compression ultrasonography as appropriate, can reduce costs and improve outcomes.

In vivo veritas: Thrombosis mechanisms in animal models

Experimental models have enhanced our understanding of atherothrombosis pathophysiology and have played a major role in the search for adequate therapeutic interventions. Various animal models have been developed to simulate thrombosis and to study in vivo parameters related to hemodynamics and rheology that lead to thrombogenesis. Although no model completely mimics the human condition, much can be learned from existing models about specific biologic processes in disease causation and therapeutic intervention. In general, large animals such as pigs and monkeys have been better suited to study atherosclerosis and arterial and venous thrombosis than smaller species such as rats, rabbits, and dogs. On the other hand, mouse models of arterial and venous thrombosis have attracted increasing interest over the past two decades, owing to direct availability of a growing number of genetically modified mice, improved technical feasibility, standardization of new models of local thrombosis, and low maintenance costs. To simulate rupture of an atherosclerotic plaque, models of arterial thrombosis often involve vascular injury, which can be achieved by several means. There is no animal model that is sufficiently tall, that can mimic the ability of humans to walk upright, and that possesses the calf muscle pump that plays an important role in human venous hemodynamics. A number of spontaneous or genetically engineered animals with overexpression or deletion of various elements in the coagulation, platelet, and fibrinolysis pathways are now available. These animal models can replicate important aspects of thrombosis in humans, and provide a valuable resource in the development of novel concepts of disease mechanisms in human patients.

Fatores de risco e profilaxia para tromboembolismo venoso em hospitais da cidade de Manaus

OBJETIVO: Identificar e classificar os fatores de risco para tromboembolismo venoso (TEV) em pacientes internados, avaliando as condutas médicas adotadas para a profilaxia da doença. MÉTODOS: Estudo observacional, de corte transversal no período de janeiro a março de 2006, envolvendo uma população de pacientes internados em três hospitais na cidade de Manaus (AM). A estratificação do risco para TEV foi feita com base nos critérios da Sociedade Brasileira de Angiologia e Cirurgia Vascular e da International Union of Angiology. Foram avaliados variáveis sobre os fatores de risco clínicos, cirúrgicos e medicamentosos, assim como os métodos profiláticos para TEV. Os dados foram analisados estatisticamente, adotando-se um alfa de 5% e IC95%. Os dados qualitativos foram analisados pelo teste do qui-quadrado e os dados quantitativos pelo teste t de Student. RESULTADOS: Foram estudados 1.036 pacientes num total de 1.051 internações, sendo 515 (49,7%) homens e 521 (50,3%) mulheres. Um total de 23 de fatores de risco para TEV foram identificados (número total de eventos, 2.319). O risco estratificado para TEV foi de 50,6%, 18,6% e 30,8% das internações para risco alto, moderado e baixo, respectivamente. Em 73,3% das internações, não foram adotadas medidas profiláticas não-medicamentosas durante o período do estudo, e em 74% das internações que apresentavam risco moderado ou alto, não foram adotadas quaisquer medidas terapêuticas medicamentosas. CONCLUSÕES: Este estudo evidenciou que, na população estudada, os fatores de risco foram frequentes e que medidas profiláticas não foram utilizadas para pacientes com riscos potenciais de desenvolverem TEV e suas complicações.

Economic evaluations of anticoagulants for the prophylaxis of venous thromboembolism following major trauma

Venous thromboembolism is a life-threatening complication in patients following major trauma. These patients are at increased risk of deep-vein thrombosis and pulmonary embolism. In the absence of a major contraindication, anticoagulant prophylaxis with either low-dose unfractionated heparin or low-molecular-weight heparin is recommended. The objectives of this study were to undertake a systematic review and critically evaluate published cost-effectiveness analyses of anticoagulant prophylaxis against deep-vein thrombosis following major trauma. The results of the identified studies varied significantly, from enoxaparin being the dominant strategy based on the cost-per-deep-vein thrombosis averted, to low-dose unfractionated heparin being the dominant strategy based on the cost per life-year gained. In general, the more comprehensive the model, the more favorable the results were towards low-dose unfractionated heparin.

Risk-based evaluation of thromboprophylaxis among surgical inpatients: are low risk patients treated unnecessarily?

BACKGROUND

Venous thromboembolism is a common source of morbidity and mortality but a variety of preventative measures are available.

AIMS

To audit the current practice of thromboprophylaxis and compare against published protocols.

METHODS

Three-hundred and seventy-six (376) surgical patients were surveyed prospectively. A Performa was completed recording the presence of up to 11 risk factors. A risk score was calculated and the use of specific thromboprophylatic measures identified.

RESULTS

Heparin thromboprophylaxis was widely used, eight patients (who were on aspirin therapy) failed to receive any prophylaxis (risk factors 4-6). In addition there were 60 patients at low risk (risk score <2) received LMWH from which they were unlikely to benefit.

CONCLUSIONS

Thromboembolic prophylaxis is widely but unselectively applied. Adoption of a risk: benefit ratio approach should ensure those who would benefit from thromboprophylaxis are adequately treated while those in whom thromboprophylaxis is not indicated are spared unnecessary therapy.

Value of quantitative D-dimer assays in identifying pulmonary embolism: implications from a sequential decision model

OBJECTIVES

To examine the cost-effectiveness of a quantitative D-dimer assay for the evaluation of patients with suspected pulmonary embolism (PE) in an urban emergency department (ED).

METHODS

The authors analyzed different diagnostic strategies over pretest risk categories on the basis of Wells criteria by using the performance profile of the ELISA D-dimer assay (over five cutoff values) and imaging strategies used in the ED for PE: compression ultrasound (CUS), ventilation-perfusion (VQ) scan (over three cutoff values), CUS with VQ (over three cutoff values), computed tomography (CT) angiogram (CTA) with pulmonary portion (CTP) and lower-extremity venous portion, and CUS with CTP. Data used in the analysis were based on literature review. Incremental costs and quality-adjusted-life-years were the outcomes measured.

RESULTS

Computed tomography angiogram with pulmonary portion and lower-extremity venous portion without D-dimer was the preferred strategy. CUS-VQ scanning always was dominated by CT-based strategies. When CTA was infeasible, the dominant strategy was D-dimer with CUS-VQ in moderate- and high-Wells patients and was D-dimer with CUS for low-Wells patients. When CTP specificity falls below 80%, or if its overall performance is markedly degraded, preferred strategies include D-dimer testing. Sensitivity analyses suggest that pessimistic assessments of CTP accuracy alter the results only at extremes of parameter settings.

CONCLUSIONS

In patients in whom PE is suspected, when CTA is available, even the most sensitive quantitative D-dimer assay is not likely to be cost-effective. When CTA is not available or if its performance is markedly degraded, use of the D-dimer assay has value in combination with CUS and a pulmonary imaging study. These conclusions may not hold for the larger domain of patients presenting to the ED with chest pain or shortness of breath in whom PE is one of many competing diagnoses.

Perioperative management of the obese orthopaedic patient

With nearly a third of American adults considered be obese, it is increasingly important that orthopaedic surgeons be familiar with management issues pertinent to these patients. Preoperative examination must assess cardiopulmonary status and other comorbid conditions, most notably diabetes. Intraoperative considerations include requirements for special equipment, patient positioning, intravenous line placement, central monitoring lines, and anesthesia specific to the physiologic changes in obese patients. Postoperatively, obese patients have higher rates of deep vein thrombosis and wound sepsis than do nonobese patients, and they may differ from other patients in supplemental oxygen requirements, medication dosing, and outcomes in intensive care units. Obese patients can successfully undergo virtually all orthopaedic procedures; however, the procedures are frequently more technically challenging, and obese patients appear to have higher rates of prosthetic failure, infection, hardware failure, and fracture malunion, although many of these complications can be minimized by appropriate countermeasures.

Economic evaluation of a clinical protocol for diagnosing emergency patients with suspected pulmonary embolism

BACKGROUND

The objective of this paper is to estimate the amount of cost-savings to the Australian health care system from implementing an evidence-based clinical protocol for diagnosing emergency patients with suspected pulmonary embolism (PE) at the Emergency department of a Victorian public hospital with 50,000 presentations in 2001-2002.

METHODS

A cost-minimisation study used the data collected in a controlled clinical trial of a clinical protocol for diagnosing patients with suspected PE. The number and type of diagnostic tests in a historic cohort of 185 randomly selected patients, who presented to the emergency department with suspected PE during an eight month period prior to the clinical trial (January 2002-August 2002) were compared with the number and type of diagnostic tests in 745 patients, who presented to the emergency department with suspected PE from November 2002 to August 2003. Current Medicare fees per test were used as unit costs to calculate the mean aggregated cost of diagnostic investigation per patient in both study groups. A t-test was used to estimate the statistical significance of the difference in the cost of resources used for diagnosing PE in the control and in the intervention group.

RESULTS

The trial demonstrated that diagnosing PE using an evidence-based clinical protocol was as effective as the existing clinical practice. The clinical protocol offers the advantage of reducing the use of diagnostic imaging, resulting in an average cost savings of at least $59.30 per patient.

CONCLUSION

Extrapolating the observed cost-savings of $59.30 per patient to the whole of Australia could potentially result in annual savings between $3.1 million to $3.7 million.

Economic and utilization outcomes associated with choice of treatment for venous thromboembolism in hospitalized patients

OBJECTIVES

Hospital administrative data were analyzed to assess treatment patterns, in-hospital mortality, rates of hemorrhagic events and thrombus propagation, utilization of health care resources, and hospital costs associated with various treatments during inpatient care for venous thromboembolism (VTE).

STUDY DESIGN

Data from inpatient records were collected for deep venous thrombosis (DVT) and pulmonary embolism (PE) encounters at 132 US hospitals between January 1999 and December 2000. Patients receiving the most frequently employed treatments were compared with respect to demographics, related procedures and diagnostics, length of stay, adverse events, in-hospital mortality, and hospital costs.

RESULTS

A total of 953 primary DVT and 3933 primary PE admissions were identified. Most admissions involved treatment with unfractionated heparin and vitamin K antagonist (UFH/VKA, 64.2% of admissions), followed by UFH with VKA and low-molecular-weight heparin (UFH/LMWH/VKA, 14.4%), and LMWH/VKA (12.9%). Compared with those treated with UFH/VKA, patients treated with LMWH/VKA experienced higher anticoagulant costs (dollar 540 vs. dollar 106), but lower total hospital costs (dollar 5198 vs. dollar 5977) and shorter lengths of stay (4.4 vs. 5.7 days for those without PE and 5.7 vs. 6.7 days for those with PE).

CONCLUSIONS

UFH/VKA was the most common regimen used to treat VTE. In spite of its higher medication cost, however, treatment with LMWH/VKA was associated with significantly shorter hospital stays and lower total hospitalization costs, compared with UFH/VKA.

Risk factors for venous thrombosis in medical inpatients: validation of a thrombosis risk score

BACKGROUND/OBJECTIVES

The occurrence of and risk factors for venous thrombosis (VT) complicating hospital admission in unselected medical inpatients have not been widely studied.

PATIENTS AND METHODS

In a 400-bed teaching hospital we identified all cases of VT complicating hospital admission between September 2000 and September 2002 using discharge codes and chart review. Controls were randomly selected adult inpatients frequency matched to cases for medical service.

RESULTS

The incidence of VT complicating hospital admission was 7.6 per 1000 admissions. On average, VT was diagnosed on the fifth hospital day. The median age of the 65 cases and 123 controls was 68 years and 45% were men. Cases had a 4-fold higher death rate than controls [95% confidence interval (CI) 1.9, 8.8]. At admission, trauma within 3 months, leg edema, pneumonia, platelet count > 350 x 10(3) mm(-3) and certain cancers were associated with risk of VT. Age, body mass index, and acute myocardial infarction were not associated with VT risk. One of three published VT risk models was able to risk stratify patients and was associated with a 2.6-fold increased risk of VT (95% CI 1.3, 5.5). Use of VT prophylaxis did not differ in cases and controls; prophylaxis was used < 1/3 of hospital days in 52% of patients.

CONCLUSIONS

VT was common among medical inpatients. Of the risk factors identified, elevated platelet count has not been previously reported. Only one of three published risk scores was associated with risk of inpatient VT. Future study should improve upon risk prediction models for in-hospital VT among medical patients.

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).

Administration of a small molecule tissue factor/factor VIIa inhibitor in a non-human primate thrombosis model of venous thrombosis: effects on thrombus formation and bleeding time

INTRODUCTION

Pharmacological treatment of deep vein thrombosis (DVT) in the future may target inhibitors of specific procoagulant proteins. This study used a non-human primate model to test the effect of PHA-798, a specific inhibitor of the tissue factor/Factor VIIa complex (TF/VIIa), on venous thrombus formation.

MATERIALS AND METHODS

PHA inhibits the TF/VIIa complex with an IC(50) of 13.5 nM (K(i) 9 nM) and is more than 2000-fold selective for the TF/VIIa complex with respect to IC(50)s for factor Xa and thrombin. In the model, a thrombogenic surface was introduced into the vena cava of a primate, and the amount of thrombus accumulated after 30 min was determined.

RESULTS

PHA-798 reduced thrombus formation on the thrombogenic surface in a dose-dependent manner (56+/-1.9% and 85+/-0.3% inhibition with 100 and 200 microg/kg/min PHA-798, respectively) indicating that the model is sensitive to TF/VIIa inhibition. Treatment with 1 mg/kg intravenous (IV) acetyl salicylic acid (ASA) resulted in only a slight (4-12%), non-significant inhibition of thrombus formation. However, the combination of 100 microg/kg/min PHA-798 and 1 mg/kg ASA resulted in an 89% inhibition of thrombus formation. Additionally, while ASA alone increased bleeding time (BT) from 3.3 min at baseline to 4.6 min following treatment, addition of PHA-798 (100 microg/kg/min) to ASA did not significantly increase the BT further (4.7 min).

CONCLUSIONS

The results of this study indicate that inhibition of TF/VIIa may be safe and effective for the prevention of the proprogation of venous thrombosis and that the combination of ASA and PHA may provide increased efficacy with little change in safety.

Is there a place for inhaled nitric oxide in the therapy of acute pulmonary embolism?

Acute pulmonary embolism (PE) is a serious complication resulting from the migration of emboli to the lungs. Although deep venous thrombi are the most common source of emboli to the lungs, other important sources include air, amniotic fluid, fat and bone marrow. Regardless of the specific source of the emboli, very little progress has been made in the pharmacological management of this high mortality condition. Because the prognosis is linked to the degree of elevation of pulmonary vascular resistance, any therapeutic intervention to improve the hemodynamics would probably increase the low survival rate of this critical condition. Inhaled nitric oxide (iNO) has been widely tested and used in cases of pulmonary hypertension of different causes. In the last few years some authors have described beneficial effects of iNO in animal models of acute PE and in anecdotal cases of massive PE. The primary cause of death in massive PE that is caused by deep venous thrombi, gas or amniotic fluid, is acute right heart failure and circulatory shock. Increased pulmonary vascular resistance following acute PE is the cumulative result of mechanical obstruction of pulmonary vessels and pulmonary arteriolar constriction (attributable to a neurogenic reflex and to the release of vasoconstrictors). As such, the vasodilator effects of iNO could actively oppose the pulmonary hypertension following PE. This hypothesis is consistently supported by experimental studies in different animal models of PE, which demonstrated that iNO decreased (by 10 to 20%) the pulmonary artery pressure without improving pulmonary gas exchange. Although maximal vasodilatory effects are probably achieved by less than 5 parts per million iNO, which is a relatively low concentration, no dose-response study has been published so far. In addition to the animal studies, a few anecdotal reports in the literature suggest that iNO may improve the hemodynamics during acute PE. However, no prospective, controlled, randomized clinical trial addressing this issue has been conducted to date. Future investigations addressing the effects of iNO combined with other drugs such as vasoconstrictors and inhibitors of phosphodiesterase III or V, may increase the responsiveness to iNO in acute PE.

Get the edge on deep vein thrombosis

Review practical DVT screening considerations to enhance assessment skills.

Fondaparinux Sodium

Fondaparinux sodium (Arixtra; fondaparinux) is the first of a new class of synthetic pentasaccharide anticoagulants that bind to antithrombin and inhibit the action of factor Xa. In three large, well designed trials, subcutaneous fondaparinux 2.5mg once daily was more effective than subcutaneous enoxaparin sodium (enoxaparin) 30 mg twice daily or 40 mg once daily at preventing venous thromboembolism (VTE) at day 11 in patients undergoing hip replacement, elective major knee or hip fracture surgery; a fourth trial demonstrated similar efficacy to enoxaparin 30 mg twice daily in hip replacement. Fondaparinux recipients had a lower incidence of proximal deep vein thrombosis (DVT) in two studies. In a meta-analysis of the four trials, patients receiving fondaparinux had a >50% reduction in the relative risk of VTE at day 11. Fondaparinux compared favourably with enoxaparin in several pharmacoeconomic analyses. In a large, controlled trial in hip fracture patients, extended prophylaxis with fondaparinux (duration 25-31 days) substantially reduced the incidence of VTE at day 25-32 compared with prophylaxis for 6-8 days, and was a cost-effective treatment strategy. Moreover, extended prophylaxis significantly decreased the rate of proximal, total and distal DVT and symptomatic VTE. Fondaparinux was generally well tolerated in clinical trials in patients undergoing major orthopaedic surgery. However, following major knee surgery and in a meta-analysis of pooled data from four trials, fondaparinux recipients had a significantly higher incidence of overt bleeding with a bleeding index > or =2, but no increase in fatal bleeding, bleeding into a critical organ or bleeding leading to reoperation. The bleeding risk is related to the timing of the first dose and when fondaparinux was initiated between 6 and 8 hours after surgery, the bleeding risk was similar to enoxaparin. Extended prophylaxis with fondaparinux was not associated with a significantly increased risk of bleeding events. In conclusion, fondaparinux is more effective than enoxaparin at preventing postoperative VTE in patients undergoing elective hip replacement, major knee or hip fracture surgery. Extended therapy with fondaparinux considerably increases its efficacy without a significant increase in the incidence of bleeding episodes. Fondaparinux was generally well tolerated in clinical trials. Fondaparinux is an effective and useful alternative to low molecular weight heparins for the prevention of VTE following major orthopaedic surgery.

Ximelagatran/Melagatran

Ximelagatran (Exanta), the first available oral direct thrombin inhibitor, and its active form, melagatran, have been evaluated in the prevention of venous thromboembolism (VTE) in patients undergoing hip or knee replacement. After oral administration ximelagatran is rapidly bioconverted to melagatran. Melagatran inactivates both circulating and clot-bound thrombin by binding to the thrombin active site, thus, inhibiting platelet activation and/or aggregation and reducing fibrinolysis time. The efficacy of subcutaneous melagatran followed by oral ximelagatran has been investigated in four European trials and the efficacy of an all oral ximelagatran regimen has been investigated in five US trials. In a dose-ranging European study, preoperatively initiated subcutaneous melagatran 3 mg twice daily followed by oral ximelagatran 24 mg twice daily was significantly more effective than subcutaneous dalteparin sodium 5000IU once daily in preventing the occurrence of VTE, including deep vein thrombosis (DVT) and pulmonary embolism (PE), in patients undergoing hip or knee replacement. In one study, there were no significant differences in VTE prevention between subcutaneous melagatran 3 mg administered after surgery followed by ximelagatran 24 mg twice daily and enoxaparin sodium (enoxaparin) 40 mg once daily. Compared with enoxaparin, significantly lower rates of proximal DVT and/or PE (major VTE) and total VTE were observed when melagatran was initiated preoperatively (2mg) then postoperatively (3mg) and followed by ximelagatran 24 mg twice daily. In the US, four studies showed that postoperatively initiated ximelagatran 24 mg twice daily was of similar efficacy to enoxaparin or warfarin in the prevention of VTE in patients undergoing hip or knee replacement. However, ximelagatran 36 mg twice daily was superior to warfarin (target international normalised ratio of 2.5) at preventing the incidence of VTE in patients undergoing total knee replacement in two studies.Ximelagatran alone or after melagatran was generally well tolerated. Overall, the incidence of bleeding events and transfusion rates were not markedly different from those documented for comparator anticoagulants. In a post-hoc analysis of one study, transfusion rates were lower in ximelagatran than enoxaparin recipients.

CONCLUSIONS

Oral ximelagatran alone or in conjunction with subcutaneous melagatran has shown good efficacy and was generally well tolerated in the prevention of VTE in patients undergoing orthopaedic surgery. Furthermore, patients receiving ximelagatran/melagatran do not require anticoagulant monitoring. The drug has a low potential for drug interactions and can be administered either by subcutaneous injection or orally. Thus, on the basis of available evidence, ximelagatran/melagatran appears poised to play an important role in the prophylaxis of VTE in patients undergoing orthopaedic surgery.

Prevention of Venous Thromboembolism in the ICU

BACKGROUND

Although venous thromboembolism (VTE) is an important cause of morbidity and mortality in critical care unit patients, the risk of VTE and its prevention have been poorly characterized in this population. Evidence-based thromboprophylaxis guidelines are also not available for these critically ill patients.

OBJECTIVES

To review the prevalence of VTE, to summarize the available clinical trials of thromboprophylaxis, and to outline a practical approach to the prevention of VTE in critical care unit patients.

METHODS

Systematic review of the relevant literature.

RESULTS

Most patients in critical care units have at least one major risk factor for VTE, and many patients have multiple risk factors. Objectively confirmed deep-vein thrombosis (DVT) rates varied from 13 to 31% among the four prospective studies in which critical care unit patients did not receive prophylaxis. We were able to identify only three randomized trials of thromboprophylaxis conducted in critical care units. The results of these studies suggest that both low-dose heparin and low-molecular-weight heparin are efficacious in preventing DVT compared with no prophylaxis. Fourteen studies reported that compliance with some form of thromboprophylaxis occurred in 33 to 100% of critically ill patients.

CONCLUSIONS

There is a paucity of data assessing the risks and prevention of VTE in critical care settings. Selection of prophylaxis for these challenging patients involves a consideration of the thromboembolic and bleeding risks, both of which may vary in the same patient from day to day.

Danaparoid: a review of its use in thromboembolic and coagulation disorders

Danaparoid (danaparoid sodium) is a low molecular weight heparinoid which has undergone clinical study for use as continued anticoagulant therapy in patients with heparin-induced thrombocytopenia (HIT), for the prophylaxis and treatment of deep vein thrombosis (DVT), and for the treatment of disseminated intravascular coagulation (DIC). A nonblind study in patients with HIT has reported that complete clinical resolution is significantly more likely in patients receiving danaparoid than in patients receiving dextran 70. In addition, retrospective analyses and noncomparative data support the use of danaparoid for continued anticoagulant therapy in patients with HIT. Studies in patients undergoing hip surgery have shown that danaparoid significantly reduces the incidence of postoperative DVT compared with aspirin, warfarin, dextran 70 and heparin-dihydroergotamine, while additional data suggest no difference between danaparoid, enoxaparin and dalteparin. In patients undergoing abdominal or thoracic surgery for removal of a malignancy, danaparoid reduced the incidence of postoperative DVT compared with placebo, but showed no significant difference when compared with unfractionated heparin (UFH). Two studies have compared danaparoid with UFH in the prophylaxis of DVT following acute ischaemic stroke; twice daily danaparoid was significantly superior to UFH whereas there was no significant difference between a once-daily dosage and UFH. Danaparoid did not differ from UFH in terms of efficacy in the treatment of existing DVT. In all comparative studies examining the efficacy of danaparoid in the prophylaxis or treatment of DVT (versus warfarin, dextran 70, enoxaparin, dalteparin, aspirin, heparin-dihydroergotamine, UFH and placebo), the incidence of haemorrhagic complications did not differ between treatment groups. In patients with DIC, 61.9% of those patients receiving danaparoid experienced either disappearance or reduction of symptoms of DIC whereas 62% of those receiving UFH showed either no change or aggravation of their symptoms. There was no significant difference between treatment groups in tolerability or overall improvement of DIC.

CONCLUSIONS

Danaparoid is an effective anticoagulant agent which has undergone clinical evaluation in a wide range of disease indications. Current guidelines support the use of danaparoid in prophylaxis of DVT following ischaemic stroke, and in patients who develop HIT. Danaparoid has shown efficacy in DIC, and for DVT prophylaxis in patients undergoing hip surgery although further data are required to establish the role of danaparoid in these indications. In particular, double-blind trials comparing danaparoid with such recommended therapies as the low molecular weight heparins will provide more definitive data on the place of danaparoid in the clinical management of these conditions and ultimately lead to improved patient outcomes.

Anticoagulant treatment in primary health care in Sweden - prevalence, incidence and treatment diagnosis: a retrospective study on electronic patient records in a registered population

BACKGROUND

The indications for warfarin treatment in primary health care are increasing. An undertreatment with warfarin is reported in the prevention of embolic stroke in patients with chronic atrial fibrillation, and can be suspected for other indications. Information on the prevalence and incidence of diseases treated with warfarin would reveal useful data for audits concerning management of anticoagulant treatment. We aimed to assess warfarin treatment in primary health care with regard to prevalence, incidence, treatment diagnosis and patient characteristics.

METHODS

A one-year retrospective study of electronic patient records up to May 2000 in primary health care in Stockholm, Sweden. Five primary health care centres with a registered population of 75 146. Main outcome measures were prevalence, incidence and treatment diagnosis.

RESULTS

Five hundred and seven patients, mean age 71.9 years, were on warfarin treatment. The prevalence was 0.67% (age-adjusted 0.75%), and it was significantly higher for men (0.78%) than for women (0.58%) (p = 0.01). In the age group 75-84 years the prevalence was 4.54%. The most prevalent treatment diagnosis was chronic atrial fibrillation (0.28%), which was more predominant for males (p = 0.02), followed by cerebrovascular disease (0.13%) and deep venous thrombosis (0.13%). The yearly incidence of warfarin treatment was 0.17%, with chronic atrial fibrillation as the predominant treatment diagnosis.

CONCLUSION

Warfarin treatment in primary health care is prevalent among the elderly. Chronic atrial fibrillation is the main treatment diagnosis. There is a gender difference favouring men in general and chronic atrial fibrillation as the treatment diagnosis.

Introduction to thrombosis proficient and cost-effective approaches to thrombosis

Thrombosis is the most common single cause of death in the United States. More than 2 million people die each year of arterial or venous thrombosis or its consequences, and a similar number experience nonfatal thrombosis-deep vein thrombosis, nonfatal pulmonary embolus, nonfatal cerebrovascular thrombosis, transient cerebral ischemic attacks (40% of patients will have a fatal or nonfatal cerebrovascular thrombosis within 1 year), nonfatal coronary artery thrombosis, retinal vascular thrombosis, and other nonfatal thrombotic episodes. Yet many, if not most, episodes of thrombosis can be prevented by appropriate primary antithrombotic therapy, and most recurrences can be prevented by the appropriate choice of secondary therapy.

Thromboprophylaxis and thrombosis in medical, surgical, trauma, and obstetric/gynecologic patients

The International Consensus and the ACCP Sixth Consensus had a great impact on the clinical acceptance of LMWHs. These recommendations have been instrumental in initiating further clinical trial to answer key questions regarding thromboprophylaxis and in setting a new standard for patient care. Also, the key to cost containment in management of DVT/PE is to (1) define the etiology (blood coagulation protein or platelet defect), institute appropriate long-term therapy as indicated, and assess appropriate family members as indicated if a hereditary defect is found and (2) use LMWH as inpatient management. saving a minimum of 210,000.00 dollars per 1000 patients simply from cost savings of recurrence, saving 17 lives per 1000 patients, and saving exorbitant costs of care for patients with recurrence and development of chronic venous insufficiency. The use of outpatient LMWH will save 4,900,000.00 dollars per 1000 patients if applied to the 70% of patients with DVT who fit the criteria of no comorbid condition requiring hospitalization and who arrive early enough to allow a diagnosis to be sent home or hospitalized for 24 hours or less. The simple defining of defects leading to unexplained thrombosis will add another 3,000,000.00 dollars in savings per 1000 patients with DVT and approximately 350,000.00 dollars per 100 patients with thrombotic stroke. In those with transient ischemic attacks, defining the defect and instituting appropriate antithrombotic therapy, thereby potentially saving approximately 30% from developing a thrombotic stroke, amounts to approximately 350,500.00 dollars (= 30% of 1,168,500.00 dollars) in savings per 100 patients.

DVT prophylaxis in the perioperative setting

This is the first of a two-part article in which Agnes Arnold examines the role of the perioperative nurse in the prophylaxis of lower limb deep vein thrombosis (DVT). This part discusses the pathophysiology of DVT and the methods of assessing an individual's risk of developing the disorder. Part 2, which will appear in the September edition of BJPN, will deal with prophylaxis of DVT. It will critically analyse the research, cost-effectiveness, side-effects and target patient population of each prophylactic regimen.

Enoxaparin: a pharmacoeconomic review of its use in the prevention and treatment of venous thromboembolism and in acute coronary syndromes

The pharmacoeconomics of the low molecular weight heparin (LMWH) enoxaparin in the prophylaxis and treatment of venous thromboembolism have mostly been investigated in cost-effectiveness studies that estimated direct costs associated with treatment, using decision analyses and clinical outcome data from randomised controlled trials. These studies have shown enoxaparin to be cost effective compared with unfractionated heparin (UFH) and warfarin in short-term thromboprophylaxis for hospital inpatients undergoing orthopaedic surgery and in thromboprophylaxis following trauma. Outpatient treatment of acute proximal deep vein thrombosis with enoxaparin has also been shown to be cost effective compared with inpatient treatment using UFH. In general surgery, however, it remains to be determined whether enoxaparin is a cost-effective alternative to UFH. The cost effectiveness of enoxaparin compared with UFH in the treatment of unstable angina and non-Q-wave myocardial infarction has also been investigated in several countries using clinical outcomes data from the Efficacy and Safety of Subcutaneous Enoxaparin in Non-Q-wave Coronary Events (ESSENCE) randomised trial. ESSENCE demonstrated that enoxaparin was superior to UFH in terms of tolerability and efficacy, and cost saving at both 30-day and 1-year follow-ups. An increasing number of studies indicate enoxaparin to be of economic benefit when used for prevention and treatment of venous thromboembolism and treatment of acute coronary symdromes.