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PubMed1982

Factors affecting fibrinopeptide-A levels in patients with venous thromboembolism during anticoagulant therapy.

The prompt reduction of elevated fibrinopeptide A (FPA) levels (normal less than 1.3 pmole/ml) by heparin therapy in patients with thromboembolism suggests that measuring the FPA level may provide a good index of disease activity and be a useful method of monitoring therapy. Sepsis or malignancy may elevate FPA levels and coexist with thromboembolism. FPA levels were surveyed in 51 patients with thromboembolism (including 15 with concurrent sepsis or malignancy) during heparin treatment in an attempt to distinguish the effects of coexistent disease and the progression of thromboembolism. The anticoagulant effect of heparin was within the therapeutic range for 81% of the study period. In patients with thromboembolism alone and marked resolution of emboli on repeat lung scan, the mean daily FPA levels were lower than the values in patients with minimal resolution (p less than 0.005). In patients with marked resolution of pulmonary embolism or venous thrombosis and a concurrent disorder, the mean FPA level remained elevated compared to normal values in patients with thromboembolism alone. These results suggest that FPA levels monitored during heparin therapy of thromboembolism may be useful as an index of disease activity except in the presence of coexisting sepsis or malignancy.

Adenocarcinoma↗
PubMed1981

Dysfunction and thromboembolism associated with cardiac valve xenografts in adults.

Cardiac valve xenografts often fail relatively early in children. We analyzed the incidence of valve dysfunction and thromboembolism in 253 consecutive adult survivors who received 294 porcine xenograft valves (150 aortic, 125 mitral and 19 tricuspid) from June 1974 to December 1979 (41% of all adult valve replacements). Mean follow-up was 25.6 months (range 9-75 months). Valve dysfunction occurred in four of 294 xenografts (three in mitral position and one in tricuspid position), all four caused by recurrent endocarditis; these four patients survived reoperation and are doing well. Thromboembolism occurred in six of 294 xenografts, none in aortic or tricuspid positions of rhythm or anticoagulation. Four of the six mitral xenografts associated with thromboembolism were in the 16 patients who had atrial fibrillation and received aspirin and dipyridamole but no warfarin (12% per patient-year), and two were in the 14 patients who were in sinus rhythm and were not taking medication, one of whom had recurrent Candida endocarditis. No thromboembolism occurred in mitral xenografts with sinus rhythm and antiplatelet agents. Thromboembolism did not occur in patients who were in atrial fibrillation and receiving warfarin anticoagulation. Late death (30 of 253) was unrelated to valve dysfunction, and only one death resulted from thromboembolism. This study showed excellent xenograft performance for as long as 75 months. Valve dysfunction occurred only with recurrent endocarditis, and thromboembolism occurred after mitral replacement, especially in patients who were in atrial fibrillation and were not receiving anticoagulants.

Adult↗
PubMed1994

Artificial circulatory support with textured interior surfaces. A counterintuitive approach to minimizing thromboembolism.

BACKGROUND: Although numerous left ventricular assist devices (LVADs) have been used clinically, frequent thromboembolic complications have been reported despite the smooth interior LVAD surfaces and systemic anticoagulant medication. In contrast, the Thermo Cardiosystems HeartMate 1000 IP LVAD has textured interior surfaces that are promptly covered by a densely adherent neointima. We hypothesize that elimination of a direct interface between prosthetic material and blood elements reduces the risk of peripheral embolization and minimizes the necessity for systemic anticoagulant medication. This report defines the thromboembolic risk of this type of LVAD and characterizes the nature and effectiveness of the various anticoagulation regimens that were tested during the initial clinical trial with this device. METHODS AND RESULTS: All values are reported as mean +/- SD. Fifty-four males and three females with an average age of 47 +/- 11 years were supported with the HeartMate 1000 IP LVAD for an average of 62 +/- 76 days at 11 clinical centers in the United States. Patients were prospectively evaluated for thromboembolic complications. Five different anticoagulation regimens were used during the first 4 postoperative weeks: no anticoagulants, low-molecular-weight dextran, heparin, dipyridamole plus aspirin, or miscellaneous agents. After the first 4 weeks, the patients were treated with aspirin plus dipyridamole or miscellaneous agents. Prothrombin time (PT), partial thromboplastin time (PTT), and fibrinogen values for the patients were measured at 0.1, 1, 2, 4, 8, 12, 16, 20, 24, 32, and 46 weeks during support. Two patients (3.5%) suffered thromboembolic cerebrovascular complications, an incidence of 0.2 episodes per patient-year of observation. One episode was due to fungal vegetation developing on the device and the other was due to embolization from a previously placed native mechanical aortic valve prosthesis. In the absence of infection, there were no device-related thromboembolic complications. Mean prothrombin time for all groups was 13.3 +/- 0.5 seconds with no significant intergroup differences. Mean partial thromboplastin time during the first 4 weeks for the heparin-treated group was 53.3 +/- 6.6 seconds, which was significantly longer than for all other groups, but fell to control values after heparin was discontinued at 4 weeks. Mean fibrinogen level for all groups was 370 +/- 48 mg/dL, with no intergroup differences. CONCLUSIONS: The HeartMate 1000 IP LVAD provides adequate circulatory support with a low risk of thromboembolism despite minimal systemic anticoagulation. The use of textured surfaces may be an important factor contributing to the low observed risk of thromboembolic complications.

Anticoagulants↗
PubMed1997

Venous thromboembolism and cancer: a two-way clinical association.

Venous thromboembolism and cancer are linked by a two way clinical association: venous thromboembolism may be the presenting feature of an occult cancer and patients with clinically overt cancer may develop a venous thromboembolic complication at any stage of their disease. Patients with venous thromboembolism in the absence of conventional risk factors have a 10% likelihood of having cancer. However, the value of investigating for underlying malignant disease in patients with idiopathic venous thrombosis who are otherwise well is still undefined: intensive diagnostic screening versus routine management is under evaluation in a randomised prospective clinical trial. Patients with cancer are at a high risk of developing postoperative venous thromboembolism. Therefore, they require prophylactic measures comparable to those usually recommended for major orthopaedic surgery. Both retrospective and prospective studies have recently focused attention on the thromboembolic risk associated with chemo- and/or hormone therapy in cancer patients. A prospective, double-blind, randomised study showed that very-low-dose warfarin is an effective and safe method for the prevention of thromboembolism in patients with metastatic breast cancer receiving chemotherapy. The evidence of lowered cancer mortality in patients receiving low molecular weight heparins has renewed interest in the antithrombotic agents as antineoplastic drugs. A multicentre study aimed at investigating this fascinating hypothesis is now being carried out.

Anticoagulants↗
PubMed1997

[Thromboembolic complications in neurosurgical patients].

This study was aimed at the analysis of thromboembolic risk factors in a large and representative group of adult neurosurgical patients. Using an open retrospectively designed mode of evaluation, 3162 inpatients treated in 5 years were investigated. Thromboembolism was diagnosed clinically and confirmed be ultrasound and phlebographic tests. Thromboembolism prophylaxis included subcutaneous injection of low-molecular-weight heparin and supporting physical therapy. In the whole patient population, 2.6% deep venous thromboses and 0.7% fulminant pulmonary embolisms were diagnosed. Risk factors such as malignant disease, ischemic disease of the heart, history of thromboembolism, age over 60 years, varicosis, and immobilisation rendered patients especially prone to thromboembolic events, increasing 2- to 3-fold their respective risk and reaching for some factors the level of statistical significance. Low-molecular-weight heparin application reduced the rate of thromboembolic complications, as compared to the group without heparin prophylaxis. Wound revision because of hematoma formation was necessary in 1.1% of all cases, and heparin did not induce an increase in the rate of wound hematoma formation. We conclude that low-molecular-weight heparin prophylaxis is able to safely reduce the rate of thromboembolic events in neurosurgical patients without producing additional drug-related surgical complications.

Adult↗
PubMedDate not supplied

Comparison of low-molecular-weight heparin and warfarin for the secondary prevention of venous thromboembolism in patients with cancer: a randomized controlled study.

BACKGROUND: The use of warfarin sodium for treating venous thromboembolism in patients with cancer is associated with a significant risk of recurrence and bleeding. The use of low-molecular-weight heparin sodium for secondary prevention of venous thromboembolism in cancer patients may reduce the complication rate. OBJECTIVE: To determine whether a fixed dose of subcutaneous low-molecular-weight heparin is superior to oral warfarin for the secondary prophylaxis of venous thromboembolism in patients with cancer and venous thromboembolism. METHODS: In a randomized, open-label multicenter trial performed between April 1995 and March 1999, we compared subcutaneous enoxaparin sodium (1.5 mg/kg once a day) with warfarin given for 3 months in 146 patients with venous thromboembolism and cancer. MAIN OUTCOME MEASURE: A combined outcome event defined as major bleeding or recurrent venous thromboembolism within 3 months. RESULTS: Of the 71 evaluable patients assigned to receive warfarin, 15 (21.1%; 95% confidence interval [CI], 12.3%-32.4%) experienced one major outcome event compared with 7 (10.5%) of the 67 evaluable patients assigned to receive enoxaparin (95% CI, 4.3%-20.3%; P =.09). There were 6 deaths owing to hemorrhage in the warfarin group compared with none in the enoxaparin group. In the warfarin group, 17 patients (22.7%) died (95% CI, 13.8%-33.8%) compared with 8 (11.3%) in the enoxaparin group (95% CI, 5.0%-21.0%; P =.07). No difference was observed regarding the progression of the underlying cancer or cancer-related death. CONCLUSIONS: These results confirm that warfarin is associated with a high bleeding rate in patients with venous thromboembolism and cancer. Prolonged treatment with low-molecular-weight heparin may be as effective as oral anticoagulants and may be safer in these cancer patients.

Adult↗
PubMed2003

Reduction of out-of-hospital symptomatic venous thromboembolism by extended thromboprophylaxis with low-molecular-weight heparin following elective hip arthroplasty: a systematic review.

BACKGROUND: Numerous trials and meta-analyses have shown that extended out-of-hospital prophylaxis with low-molecular-weight heparin reduces asymptomatic and symptomatic venous thromboembolism after total hip arthroplasty. We hypothesized that knowledge of the results of screening tests may have resulted in overdiagnosis of symptomatic venous thromboembolism in many of these studies. The purpose of this analysis was to obtain an accurate estimate of the absolute risk reduction (ARR) of symptomatic venous thromboembolism after discharge from hospital in controlled studies that avoided this potential bias for overdiagnosis. METHODS: Articles were identified using MEDLINE, EMBASE, and the Cochrane Library databases (January 1980-April 2002). Studies were eligible if the assessment of symptomatic venous thromboembolism was standardized and performed independently of mandatory objective testing. RESULTS: Two studies (907 patients) were eligible for assessment of symptomatic venous thromboembolism, 5 studies (1917 patients) for symptomatic pulmonary embolism, and 7 studies (2425 patients) for fatal pulmonary embolism. In controls vs extended treatment groups, after hospital discharge, the frequency of symptomatic venous thromboembolism was 2.7% vs 1.1% (ARR, 1.56%; 95% confidence interval [CI], -0.21% to 3.3%; number needed to treat, 64); symptomatic pulmonary embolism was 0.36% vs 0% (ARR, 0.36%; 95% CI, -0.3% to 1.36%; number needed to treat, 278); and fatal pulmonary embolism was 0.09% vs 0% (ARR, 0.09%; 95% CI, -0.08% to 0.27%; number needed to treat, 1093). CONCLUSIONS: The absolute reduction in symptomatic venous thromboembolism attributed to extended prophylaxis in some studies and meta-analyses seems to have been overestimated.

Arthroplasty, Replacement, Hip↗
PubMed2006

Comparison of fixed-dose weight-adjusted unfractionated heparin and low-molecular-weight heparin for acute treatment of venous thromboembolism.

CONTEXT: When unfractionated heparin is used to treat acute venous thromboembolism, it is usually administered by intravenous infusion with coagulation monitoring, which requires hospitalization. However, subcutaneous administration of fixed-dose, weight-adjusted, unfractionated heparin may be suitable for inpatient and outpatient treatment of venous thromboembolism. OBJECTIVE: To determine if fixed-dose, weight-adjusted, subcutaneous unfractionated heparin is as effective and safe as low-molecular-weight heparin for treatment of venous thromboembolism. DESIGN, SETTING, AND PATIENTS: Randomized, open-label, adjudicator-blinded, noninferiority trial of 708 patients aged 18 years or older with acute venous thromboembolism from 6 university-affiliated clinical centers in Canada and New Zealand conducted from September 1998 through February 2004. Of the randomized patients, 11 were subsequently excluded from the analysis of efficacy and 8 from the analysis of safety. INTERVENTIONS: Unfractionated heparin was administered subcutaneously as an initial dose of 333 U/kg, followed by a fixed dose of 250 U/kg every 12 hours (n = 345). Low-molecular-weight heparin (dalteparin or enoxaparin) was administered subcutaneously at a dose of 100 IU/kg every 12 hours (n = 352). Both treatments could be administered out of hospital and both were overlapped with 3 months of warfarin therapy. MAIN OUTCOME MEASURES: Recurrent venous thromboembolism within 3 months and major bleeding within 10 days of randomization. RESULTS: Recurrent venous thromboembolism occurred in 13 patients in the unfractionated heparin group (3.8%) compared with 12 patients in the low-molecular-weight heparin group (3.4%; absolute difference, 0.4%; 95% confidence interval, -2.6% to 3.3%). Major bleeding during the first 10 days of treatment occurred in 4 patients in the unfractionated heparin group (1.1%) compared with 5 patients in the low-molecular-weight heparin group (1.4%; absolute difference, -0.3%; 95% confidence interval, -2.3% to 1.7%). Treatment was administered entirely out of hospital in 72% of the unfractionated heparin group and 68% of the low-molecular-weight heparin group. CONCLUSION: Fixed-dose subcutaneous unfractionated heparin is as effective and safe as low-molecular-weight heparin in patients with acute venous thromboembolism and is suitable for outpatient treatment. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00182403.

Aged↗
PubMed2000

Duration of treatment with vitamin K antagonists in symptomatic venous thromboembolism.

BACKGROUND: Currently the most frequently used secondary treatment for patients with venous thromboembolism are vitamin K antagonists targeted at an INR of 2.5 (range 2.0 - 3.0). However, based on the continuing risk of bleeding and uncertainty regarding the risk of recurrent venous thromboembolism, there is discussion on the proper duration of treatment with vitamin K antagonists for these patients. Recently, several studies were published in which the risk and benefits of different durations of oral anticoagulants were compared in patients with venous thromboembolism. OBJECTIVES: The objective of this review was to evaluate efficacy and safety of different durations of treatment with vitamin K antagonists in patients with symptomatic venous thromboembolism. SEARCH STRATEGY: The reviewers sought publications through computerized searches of MEDLINE and EMBASE, and by hand-searching relevant journals, using the search strategy described by the Cochrane Review Group on Peripheral Vascular Diseases. They also contacted colleagues. SELECTION CRITERIA: Randomized controlled clinical trials comparing different durations of treatment with vitamin K antagonists in patients with symptomatic venous thromboembolism. DATA COLLECTION AND ANALYSIS: Two reviewers extracted the data and assessed the quality of the trials independently. MAIN RESULTS: Four studies with a total of exactly 1500 patients were included. A consistent reduction for the risk of recurrent events was observed during prolonged treatment with vitamin K antagonists (OR 0.15; 95% CI [0.10 - 0.23]) independent of the period elapsed since the index thrombotic event. A 'rebound' phenomenon, i.e. an excess of recurrences shortly after cessation of the prolonged treatment was not observed (OR 1.11; 95% CI [0.71 - 1.75]). In addition, a substantial increase in bleeding complications was found during the entire period after randomization (OR 7.75; 95% CI [1.08 - 55.57]). REVIEWER'S CONCLUSIONS: In conclusion this meta-analysis shows that treatment with vitamin K antagonists reduces the risk of recurrent venous thromboembolism as long as it is used. However, the absolute risk of recurrent venous thromboembolism declines over time, while the risk for major bleeding remains. Thus, the efficiency of vitamin K antagonist administration decreases over time since the index event.

Anticoagulants↗
PubMed2006

Venous thromboembolism: a review of risk and prevention in colorectal surgery patients.

Hospitalization for surgery has a high risk of developing venous thromboembolism, a condition that encompasses both deep-vein thrombosis and its potentially fatal complication, pulmonary embolism. Colorectal surgery implies a specific high risk for postoperative thromboembolic complications relative to other general surgery. This may be a result of pelvic dissection, the perioperative positioning of these patients, or the presence of additional risk factors common to this patient group, such as cancer, advanced age, or inflammatory bowel disease. The potential impact of venous thromboembolism and the need for effective thromboprophylaxis often are underestimated in these patients. Recommendations for thromboprophylaxis in colorectal surgery patients are based on the American College of Chest Physicians guidelines for thrombosis prevention in general surgery patients, with treatment stratified according to the type of surgery and additional venous thromboembolism risk factors present. Prophylaxis with low-molecular-weight heparin or unfractionated heparin is recommended for colorectal surgery patients classified as moderate to high risk. The small number of studies focusing specifically on colorectal patients, or on cancer or abdominal surgery patients with a colorectal subgroup, has shown that both low-molecular-weight heparin and unfractionated heparin can effectively reduce the incidence of venous thromboembolism. Low-molecular-weight heparin has the practical advantage of once-daily administration and shows a lower risk of heparin-induced thrombocytopenia. This review will assess the risk of venous thromboembolism in colorectal surgery patients and discuss current evidence-based guidelines and recommendations for prevention of venous thromboembolism.

Anticoagulants↗
PubMed1990

Venous thromboembolism in patients with major trauma.

The risk of venous thromboembolism after trauma is thought to be high, but the specific risk factors and the incidence of venous thromboembolism in the trauma population are poorly defined. Between October 1, 1987, and March 1, 1988, 719 patients were evaluated; 542 had no risk factors and 177 had at least 1 risk factor. No venous thromboembolism occurred in any of the 542 patients without a risk factor, whereas 12 of 177 patients (7%) with at least 1 risk factor had a venous thromboembolism. Pneumatic compression hose was the most common form of prophylaxis used, but it could not be applied to 35% of limbs because of plaster immobilizers, external fixators, complex wounds, or traction. In the high-risk group, 25 patients (14%) received no prophylaxis because of a physical impediment to application of these hose and a contraindication to anticoagulation. Age greater than 45 years was the only risk factor predictive of venous thromboembolism by logistic regression analysis. Patients with more than one risk factor had a significantly higher incidence of venous thromboembolism than those with only one risk factor. We conclude that a selected subgroup of trauma patients appears to be at risk of venous thromboembolism and should receive prophylaxis. Approximately one in seven high-risk patients cannot receive anticoagulant or mechanical prophylaxis because of their injuries.

Adult↗
PubMed1997

Evaluation of the combination of a bedside D-dimer assay and enzyme-linked immunosorbent soluble fibrin assay in patients with suspected venous thromboembolism.

The objectives of the study were to determine whether the combination of a negative SimpliRED D-dimer assay and a low soluble fibrin result reliably excludes venous thromboembolism, and whether patients with proven venous thromboembolism and a normal SimpliRED D-dimer have evidence of impaired fibrinolysis. The study was a retrospective analysis of a cohort of 262 consecutive patients, 94 patients presenting with suspected deep venous thrombosis and 168 with suspected pulmonary embolism. Fifty-nine patients (22.5%) were classified as venous thromboembolism-positive, 27 with pulmonary embolism, and 32 with deep venous thrombosis. One hundred and fourteen patients (43.5%) had SimpliRED D-dimer and a soluble fibrin result of less than or equal to 2.0 microg/ml; the negative predictive value was 98.2% (95% confidence interval: 93.8-99.8%), and the likelihood ratio was 0.06. Eight patients with proven venous thromboembolism had a negative SimpliRED D-dimer; all had elevated ELISA D-dimer levels and six had elevated soluble fibrin levels. This suggests that patients with venous thromboembolism and a normal SimpliRED result do not have impaired fibrinolysis as a cause of their false-negative result. This study suggests that the combination of SimpliRED and soluble fibrin can be used to exclude venous thromboembolism in over 40% of patients who present with a clinical suspicion of deep venous thrombosis or pulmonary embolism and that the small group of patients with venous thromboembolism and a normal SimpliRED do not have impaired fibrinolysis.

Enzyme-Linked Immunosorbent Assay↗
PubMed1998

Evaluation of role of factor V Leiden mutation in fatal pulmonary thromboembolism.

Association of a mutation in the coagulation factor V gene (FV Leiden) with deep vein thrombosis and pulmonary thromboembolism has been well documented in the literature, but no study has specifically screened cases of fatal pulmonary thromboembolism for the mutation. This study sought to determine whether FV Leiden plays a role in the pathogenesis of fatal pulmonary thromboembolism. We isolated DNA from archived paraffin-embedded tissues derived from 46 necropsy cases in which pulmonary thromboembolism was listed as the cause of death (n = 27) or was secondarily associated with death (n = 19). FV Leiden genotypes were determined by using polymerase chain reaction and MnlI digestion of amplified products. The Leiden mutation occurred in the heterozygous state in one (2.1%) of the necropsy specimens. The prevalence of the mutation was higher (8.7%) in gender- and ethnic-matched blood donor controls. The FV Leiden mutation is not independently associated with fatal pulmonary thromboembolism in the group of patients analyzed. The results suggest different etiologies for nonfatal, chronic deep vein thrombosis/pulmonary thromboembolism and fatal, acute pulmonary thromboembolism.

Adolescent↗
PubMed1999

Non-invasive diagnosis of venous thromboembolism in outpatients.

BACKGROUND: We designed a simple and integrated diagnostic algorithm for acute venous thromboembolism based on clinical probability assessment of deep-vein thrombosis (DVT) or pulmonary embolism (PE), plasma D-dimer measurement, lower-limb venous compression ultrasonography, and lung scan to reduce the need for phlebography and pulmonary angiography. METHODS: 918 consecutive patients presenting at the emergency ward of the Geneva University Hospital, Geneva, Switzerland, and Hôpital Saint-Luc, Montreal, Canada, with clinically suspected venous thromboembolism were entered into a sequential diagnostic protocol. Patients in whom venous thromboembolism was deemed absent were not given anticoagulants and were followed up for 3 months. FINDINGS: A normal D-dimer concentration (<500 microg/L by a rapid ELISA) ruled out venous thromboembolism in 286 (31%) members of the study cohort, whereas DVT by ultrasonography established the diagnosis in 157 (17%). Lung scan was diagnostic in 80 (9%) of the remaining patients. Venous thromboembolism was also deemed absent in patients with low to intermediate clinical probability of DVT and a normal venous ultrasonography (236 [26%] patients), and in patients with a low clinical probability of PE and a non-diagnostic result on lung scan (107 [12%] patients). Pulmonary angiography and phlebography were done in only 50 (5%) and 2 (<1%) of the patients, respectively. Hence, a non-invasive diagnosis was possible in 866 (94%) members of the entire cohort. The 3-month thromboembolic risk in patients not given anticoagulants, based on the results of the diagnostic protocol, was 1.8% (95% CI 0.9-3.1). INTERPRETATION: A diagnostic strategy combining clinical assessment, D-dimer, ultrasonography, and lung scan gave a non-invasive diagnosis in the vast majority of outpatients with suspected venous thromboembolism, and appeared to be safe.

Acute Disease↗
PubMed1998

Heparin and low-molecular-weight heparin in the treatment of venous thromboembolism.

Venous thromboembolism (deep vein thrombosis and pulmonary embolism) continues to constitute a major clinical challenge. Effective and safe prophylactic measures against venous thromboembolism are now available for most high risk patients. In spite of this, pulmonary embolism is responsible for approximately 150,000 to 200,000 deaths per year in the United States alone. Over the past 20 years, based on a number of high quality (Level I) clinical trials, patterns of practice with respect to the treatment of venous thromboembolism have changed dramatically. The standard treatment of venous thromboembolism has been the use of unfractionated heparin by continuous intravenous infusion, with laboratory monitoring using the activated partial thromboplastin time (APTT), with warfarin starting on day 1 or 2 and continued for 3 months. Unfractionated heparin has withstood the test of time and has been shown to be safe and effective in preventing recurrent venous thromboembolism and death in numerous clinical trials. The response of individual patients to heparin is highly variable, requiring frequent laboratory monitoring. Heparin has a number of other troublesome side effects including bleeding, heparin-induced thrombocytopenia and osteoporosis. The low-molecular-weight heparins have a number of advantages over unfractionated heparin. In particular, their increased bio-availability and prolonged half-life permit once daily subcutaneous injections and their predictable antithrombotic response based on body weight permits treatment without laboratory monitoring. Low-molecular-weight heparin in therapeutic doses causes less bleeding than unfractionated heparin and evidence is accumulating that the incidence of heparin-induced thrombocytopenia and osteoporosis are decreased as well. In individual clinical trials and meta-analyses, low-molecular-weight heparin treatment results in decreased recurrent thromboembolism, major bleeding and death when compared with unfractionated heparin in the treatment of deep vein thrombosis and pulmonary embolism. These agents have also been shown to be both effective and safe for the out-of-hospital treatment of venous thrombosis. Therefore, in many countries, low-molecular-weight heparin has replaced unfractionated heparin for the treatment of venous thromboembolism.

Anticoagulants↗
PubMed1997

Low-molecular-weight heparin in the treatment of patients with venous thromboembolism.

BACKGROUND: Low-molecular-weight heparin is known to be safe and effective for the initial treatment of patients with proximal deep-vein thrombosis. However, its application to pulmonary embolism or previous episodes of thromboembolism has not been studied. METHODS: We randomly assigned 1021 patients with symptomatic venous thromboembolism to fixed-dose, subcutaneous low-molecular-weight heparin (reviparin sodium) or adjusted-dose, intravenous unfractionated heparin. Oral anticoagulant therapy with a coumarin derivative was started concomitantly and continued for 12 weeks. Approximately one third of the patients had associated pulmonary embolism. The outcome events studied over the 12 weeks were symptomatic recurrent venous thromboembolism, major bleeding, and death. We sought to determine whether low-molecular-weight heparin is at least equivalent to unfractionated heparin in patients with venous thromboembolism. RESULTS: Twenty-seven of the 510 patients assigned to low-molecular-weight heparin (5.3 percent) had recurrent thromboembolic events, as compared with 25 of the 511 patients assigned to unfractionated heparin (4.9 percent). The difference of 0.4 percentage point indicates that the two therapies have equivalent value according to our predetermined definition of equivalence. Sixteen patients assigned to low-molecular-weight heparin (3.1 percent) and 12 patients assigned to unfractionated heparin (2.3 percent) had episodes of major bleeding (P= 0.63), and the mortality rates in the two groups were 7.1 percent and 7.6 percent, respectively (P=0.89). CONCLUSIONS: Fixed-dose, subcutaneous low-molecular-weight heparin is as effective and safe as adjusted-dose, intravenous unfractionated heparin for the initial management of venous thromboembolism, regardless of whether the patient has pulmonary embolism or a history of venous thromboembolism.

Anticoagulants↗
PubMed2000

High plasma levels of factor VIII and the risk of recurrent venous thromboembolism.

BACKGROUND: A high plasma level of factor VIII is a risk factor for venous thromboembolism. We evaluated the risk of a recurrence of thrombosis after an initial episode of spontaneous venous thromboembolism among patients with high plasma levels of factor VIII. METHODS: We studied 360 patients for an average follow-up period of 30 months after a first episode of venous thromboembolism and discontinuation of oral anticoagulants. Patients who had recurrent or secondary venous thromboembolism, a congenital deficiency of an anticoagulant, the lupus anticoagulant, hyperhomocysteinemia, cancer, or a requirement for long-term treatment with antithrombotic drugs or who were pregnant were excluded. The end point was objectively documented, symptomatic recurrent venous thromboembolism. RESULTS: Recurrent venous thromboembolism developed in 38 of the 360 patients (10.6 percent). Patients with recurrence had higher mean (+/-SD) plasma levels of factor VIII than those without recurrence (182+/-66 vs. 157+/-54 IU per deciliter, P=0.009). The relative risk of recurrent venous thrombosis was 1.08 (95 percent confidence interval, 1.04 to 1.12; P<0.001) for each increase of 10 IU per deciliter in the plasma level of factor VIII. Among patients with a factor VIII level above the 90th percentile of the values in the study population, the likelihood of recurrence at two years was 37 percent, as compared with a 5 percent likelihood among patients with lower levels (P<0.001). Among patients with plasma factor VIII levels above the 90th percentile, as compared with those with lower levels, the overall relative risk of recurrence was 6.7 (95 percent confidence interval, 3.0 to 14.8) after adjustment for age, sex, the presence or absence of factor V Leiden or the G20210A prothrombin mutation, and the duration of oral anticoagulation. CONCLUSIONS: Patients with a high plasma level of factor VIII have an increased risk of recurrent venous thromboembolism.

Factor VIII↗
PubMed2000

Risk factor scoring for predicting venous thromboembolism in obstetric patients.

OBJECTIVE: The aim of this study was to develop a risk factor scoring system for the prediction of venous thromboembolism in obstetric patients. STUDY DESIGN: We conducted a retrospective case-control study of all pregnant or postpartum women admitted to the Jack D. Weiler Hospital from 1987 through 1998 with a discharge diagnosis indicating thromboembolism. For each study subject the three women who were delivered immediately before that index patient were selected for the control group. Data collected included the following: history of thrombosis, age, body mass index, previous abdominal surgical procedures, presence of systemic diseases, and blood type. Each patient was assigned a score that was based on the risk factors identified. RESULTS: We identified 21 patients who had sustained thromboembolic events during pregnancy or 6 weeks post partum. Nineteen of the thromboembolic events (90%) were diagnosed during pregnancy, and these cases were distributed throughout gestation-8 (42%) in the first trimester, 2 (10%) in the second trimester, and 9 (48%) in the third trimester. Six (28%) of these patients had pulmonary embolisms. Two cases of postpartum thromboembolic events were documented. Both were cases of pulmonary embolism. There was 1 maternal death. Patients with a score >2 were at significantly increased risk for having a thromboembolism, with an odds ratio of 4.8 (P <.05). The sensitivity, specificity, positive predictive value, and negative predictive value of this cutoff point were 21%, 95%, 57%, and 78%, respectively. CONCLUSION: Obstetric patients with high risk factor scores were at increased risk for thromboembolism.

ABO Blood-Group System↗