The role of activated protein C resistance in the pathogenesis of venous thrombosis

Utility of the Clinical Practice of Admnistering Thrombophilic Screening and Antithrombotic Prophylaxis with Low-Molecular-Weight Heparin to Healthy Donors Treated with G-Csf for Mobilization of Peripheral Blood Stem Cells

The aim of the study was to verify the utility of the clinical practice of administering thrombophilic screening and antithrombotic prophylaxis with low-molecular-weight heparin to healthy donors receiving granulocyte colony-stimulating factor to mobilize peripheral blood stem cells. Thrombophilia screening comprised of testing for factor V Leiden G1691A, prothrombin G20210A, the thermolabile variant (C677T) of the methylene tetrahydrofolate reductase gene, protein C, protein S, factor VIII and homocysteine plasmatic levels, antithrombin III activity, and acquired activated protein C resistance.

We investigated prospectively 72 white Italian healthy donors, 39 men and 33 women, with a median age of 42 years (range, 18-65). Five donors (6.9%) were heterozygous carriers of Factor V Leiden G1691A; two healthy donors had the heterozygous prothrombin G20210A gene mutation; C677T mutation in the methylene tetrahydrofolate reductase gene was present in 34 (47.2%) donors in heterozygous and in 7 donors (9.7%) in homozygous.

Acquired activated protein C resistance was revealed in 8 donors of the study (11.1%). The protein C plasmatic level was decreased in 3 donors (4.2%); the protein S level was decreased in 7 donors (9.7%). An elevated factor VIII dosage was shown in 10 donors (13.9%) and hyperhomocysteinemia in 9 donors (12.5%). Concentration of antithrombin III was in the normal range for all study group donors. The factor V Leiden mutation was combined with the heterozygous prothrombin G20210A in 2 cases and with protein S deficiency in one case; 2 healthy donors presented an associated deficiency of protein C and protein S. Although none of these healthy subjects had a previous history of thrombosis, low-molecular-weight heparin was administered to all donors during granulocyte colony-stimulating factor administration to prevent thrombotic events. No donor experienced short or long-term thrombotic diseases after a median follow-up of 29.2 months.

Our data do not support this clinical practice because there is no evidence that the combination of granulocyte colony-stimulating factor to previous hypercoagulable conditions results in thrombotic events.

Using multiple sources of data for surveillance of postoperative venous thromboembolism among surgical patients treated in Department of Veterans Affairs hospitals, 2005-2010

BACKGROUND

There are limitations to using administrative data to identify postoperative venous thromboembolism (VTE). We used a novel approach to quantify postoperative VTE events among Department of Veterans Affairs (VA) surgical patients during 2005-2010.

METHODS

We used VA administrative data to exclude patients with VTE during 12 months prior to surgery. We identified probable postoperative VTE events within 30 and 90 days post-surgery in three settings: 1) pre-discharge inpatient, using a VTE diagnosis code and a pharmacy record for anticoagulation; 2) post-discharge inpatient, using a VTE diagnosis code followed by a pharmacy record for anticoagulation within 7 days; and 3) outpatient, using a VTE diagnosis code and either anticoagulation or a therapeutic procedure code with natural language processing (NLP) to confirm acute VTE in clinical notes.

RESULTS

Among 468,515 surgeries without prior VTE, probable VTEs were documented within 30 and 90 days in 3,931 (0.8%) and 5,904 (1.3%), respectively. Of probable VTEs within 30 or 90 days post-surgery, 47.8% and 62.9%, respectively, were diagnosed post-discharge. Among post-discharge VTE diagnoses, 86% resulted in a VA hospital readmission. Fewer than 25% of outpatient records with both VTE diagnoses and anticoagulation prescriptions were confirmed by NLP as acute VTE events.

CONCLUSION

More than half of postoperative VTE events were diagnosed post-discharge; analyses of surgical discharge records are inadequate to identify postoperative VTE. The NLP results demonstrate that the combination of VTE diagnoses and anticoagulation prescriptions in outpatient administrative records cannot be used to validly identify postoperative VTE events.

Squamous cell carcinoma lung: Presented with bilateral lower limb deep venous thrombosis with gangrene formation

Bilateral venous thrombosis due to underlying malignancy is a rare entity. It is worthy to search for malignancy in patients of bilateral venous gangrene. Our patient presented with severe bilateral leg pain as a result of venous gangrene. There was associated left sided massive pleural effusion with scalp nodule. Fine needle aspiration cytology of scalp nodule revealed metastatic squamous cell carcinoma and fiber optic bronchoscopy guided biopsy from growth at left upper lobe bronchus confirmed the case as squamous cell carcinoma lung. It was rare for squamous cell carcinoma lung to present as bilateral venous gangrene with anticardiolipin antibody negative.

Anticoagulation duration in heterozygous factor V Leiden: a decision analysis

BACKGROUND

Current anticoagulation guidelines suggest that optimal anticoagulation duration for unprovoked venous thromboembolism is determined by an individual risk assessment, balancing risks of anticoagulation bleeding with venous thromboembolism recurrence. Among individuals heterozygous for the factor V Leiden mutation, while venous thromboembolism recurrence risk is greater, the risk for bleeding is recognized to be lower, suggesting longer duration anticoagulation could be considered.

OBJECTIVE

The objective of this study was to compare standard vs. lifelong anticoagulation in 20-year-old factor V Leiden heterozygotes with unprovoked venous thromboembolism.

METHODS

A Markov state-transition model was used, incorporating risks of major, minor, and fatal anticoagulation bleeding, bleeding and thromboembolism morbidity and mortality, and quality of life utilities. Model parameter values favoring lifelong anticoagulation in factor V Leiden heterozygotes were determined in sensitivity analyses. Outcomes were in quality-adjusted life years, discounted at 3% per year.

RESULTS

In general population groups with odds ratios for venous thromboembolism recurrence and anticoagulation bleeding of 1.0, a short-term anticoagulation strategy gained 0.09 quality-adjusted life years more than a lifelong anticoagulation strategy. By contrast, in factor V Leiden heterozygotes, lifetime anticoagulation was favored if their relative risk of venous thromboembolism was greater than 1.07 or their relative risk for bleeding was less than 0.91. Results were relatively insensitive to individual variation in other parameter values.

CONCLUSION

Lifelong anticoagulation may benefit individuals heterozygous for factor V Leiden and previous idiopathic venous thromboembolism. Studies assessing bleeding risk with anticoagulation in factor V Leiden heterozygotes and the costs of indefinite anticoagulation are needed to determine if lifelong anticoagulation is the optimal strategy.

Cost-effectiveness of rivaroxaban in the prevention of venous thromboembolism: A Canadian analysis using the Ontario Ministry of Health Perspective

OBJECTIVES

A cost-effectiveness model for rivaroxaban evaluated the cost-effectiveness of prophylaxis with rivaroxaban (a once-daily, orally administered Factor Xa inhibitor) vs enoxaparin in the prevention of venous thromboembolism (VTE) after total hip replacement (THR) and total knee replacement (TKR). This Canadian analysis was conducted using the Ontario Ministry of Health perspective over a 5-year time horizon. The model combined clinical data and builds upon existing economic models.

METHODS

The model included both acute VTE (represented as a decision tree) and long-term complications (represented as a Markov process with 1-year cycles) phases. The model allowed VTE event rates, quality-adjusted life expectancy and direct medical costs to be estimated over a 5-year time horizon, based on current approved practice patterns in Canada. A number of one-way sensitivity analyses were performed on the baseline assumptions, including a comparison of rivaroxaban with dalteparin, and probabilistic sensitivity analyses were performed to address any uncertainty concerning model inputs.

RESULTS

When comparing equal durations of therapy, rivaroxaban dominated enoxaparin in the prevention of VTE events in patients undergoing THR and TKR, providing more benefit at a lower cost. Rivaroxaban was cost-effective when comparing 35 days' prophylaxis with 14 days' prophylaxis with enoxaparin following THR. One-way and probabilistic sensitivity analyses demonstrated that the results of the economic analysis were robust to variations in key inputs. Rivaroxaban remained dominant during one-way sensitivity analyses comparing rivaroxaban with dalteparin after THR or TKR.

LIMITATIONS

Although clinical trial data were used in the prophylaxis module, assumptions and values used in the post-prophylaxis and long-term complication (LTC) modules were based on several different literature sources; it was not always possible to source Canadian data.

CONCLUSIONS

This economic analysis suggests that the use of rivaroxaban for the prophylaxis of VTE after THR or TKR in Canada was cost-effective.

Thromboprophylaxis rates in US medical centers: success or failure?

BACKGROUND

As hospitalized medical patients may be at risk of venous thromboembolism (VTE), evidence-based guidelines are available to help physicians assess patients' risk for VTE, and to recommend prophylaxis options. The rate of appropriate thromboprophylaxis use in at-risk medical inpatients was assessed in accordance with the 6th American College of Chest Physicians (ACCP) guidelines.

METHODS

Hospital discharge information from the Premier Perspective(trade mark) inpatient data base from January 2002 to September 2005 was used. Included patients were 40 years old or more, with a length of hospital stay of 6 days or more, and had no contraindications for anticoagulation. The appropriateness of VTE thromboprophylaxis was determined in seven groups with acute medical conditions by comparing the daily thromboprophylaxis usage, including type of thromboprophylaxis, dosage of anticoagulant and duration of thromboprophylaxis, with the ACCP recommendations.

RESULTS

A total of 196 104 discharges from 227 hospitals met the inclusion criteria. The overall VTE thromboprophylaxis rate was 61.8%, although the appropriate thromboprophylaxis rate was only 33.9%. Of the 66.1% discharged patients who did not receive appropriate thromboprophylaxis, 38.4% received no prophylaxis, 4.7% received mechanical prophylaxis only, 6.3% received an inappropriate dosage, and 16.7% received an inappropriate prophylaxis duration based on ACCP recommendations.

CONCLUSIONS

This study highlights the low rates of appropriate thromboprophylaxis in US acute-care hospitals, with two-thirds of discharged patients not receiving prophylaxis in accordance with the 6th ACCP guidelines. More effort is required to improve the use of appropriate thromboprophylaxis in accordance with the ACCP recommendations.

Results of a Survey of Hospital Coagulation Laboratories in the United States, 2001

Context.—Coagulation and bleeding problems are associated with substantial morbidity and mortality, and inappropriate testing practices may lead to bleeding or thrombotic complications.

Objective.—To evaluate practices reported by hospital coagulation laboratories in the United States and to determine if the number of beds in a hospital was associated with different practices.

Design.—From a sampling frame of institutions listed in the 1999 directory of the American Hospital Association, stratified into hospitals with 200 or more beds (“large hospitals”) and those with fewer than 200 beds (“small hospitals”), we randomly selected 425 large hospitals (sampling rate, 25.6%) and 375 small hospitals (sampling rate, 8.8%) and sent a survey to them between June and October 2001. Of these, 321 large hospitals (75.5%) and 311 small hospitals (82.9%) responded.

Results.—An estimated 97.1% of respondents reported performing some coagulation laboratory tests. Of these, 71.6% reported using 3.2% sodium citrate as the specimen anticoagulant to determine prothrombin time (81.3% of large vs 67.7% of small hospitals, P < .001). Of the same respondents, 45.3% reported selecting thromboplastins insensitive to heparin in the therapeutic range when measuring prothrombin time (59.4% of large vs 39.8% of small hospitals, P < .001), and 58.8% reported having a therapeutic range for heparin (72.9% of large vs 53.2% of small hospitals, P < .001). An estimated 96.3% of respondents assayed specimens for activated partial thromboplastin time within 4 hours after phlebotomy, and 89.4% of respondents centrifuged specimens within 1 hour of collection. An estimated 12.1% reported monitoring low-molecular-weight heparin therapy, and to do so, 79% used an assay for activated partial thromboplastin time (58% of large vs 96% of small hospitals, P = .001), whereas 38% used an antifactor Xa assay (65% of large vs 18% of small hospitals, P = .001).

Conclusions.—Substantial variability in certain laboratory practices was evident. Where significant differences existed between the hospital groups, usually large hospitals adhered to accepted practice guidelines to a greater extent. Some reported practices are not consistent with current recommendations, showing a need to understand the reasons for noncompliance so that better adherence to accepted standards of laboratory practice can be promoted.

Four-color multiplex 5' nuclease assay for the simultaneous detection of the factor V Leiden and the prothrombin G20210A mutations

We developed a real-time multiplex four-color assay for the simultaneous detection of the factor V Leiden (FVL) and prothrombin (PT) G20210A mutations in one closed tube using a single thermocycling protocol. The assay combines the power of multiplex PCR with the specificity provided by allele-specific oligonucleotide (ASO) hybridization using the 5' nuclease assay format. Human genomic DNA is prepared from whole blood with standard procedures. A 97-bp DNA sequence of the coagulation factor V gene is co-amplified with a 111-bp DNA sequence of the coagulation factor II (PT) gene using four PCR primers. In addition, the reactions included four differentially labeled ASO probes for the specific detection of the different FVL/PT G20210A genotypes. To evaluate the assay's performance characteristics, we performed a comparison of two methods. We analyzed DNA samples from 52 individuals with known FVL/PT G20210A genotypes that were previously genotyped with an assay that combined PCR with the use of restriction fragment length polymorphisms. We found a 100% concordance between the results generated by both methodologies. We conclude that the four-color multiplex assay is specific and reproducible for the detection of the FVL/PT G20210A mutations, and it can be easily adapted for the detection of other SNPs.

Real-time genotyping with oligonucleotide probes containing locked nucleic acids

Oligonucleotide probes containing locked nucleic acid (LNA) hybridize to complementary single-stranded target DNA sequences with an increased affinity compared to oligonucleotide DNA probes. As a consequence of the incorporation of LNA residues into the oligonucleotide sequence, the melting temperature of the oligonucleotide increases considerably, thus allowing the successful use of shorter LNA probes as allele-specific tools in genotyping assays. In this article, we report the use of probes containing LNA residues for the development of qualitative fluorescent multiplex assays for the detection of single nucleotide polymorphisms (SNPs) in real-time polymerase chain reaction using the 5'-nuclease detection assay. We developed two applications that show the improved specificity of LNA probes in assays for allelic discrimination. The first application is a four-color 5'-nuclease assay for the detection of SNPs for two of the most common genetic factors involved in thrombotic risk, factor V Leiden and prothrombin G20210A. The second application is a two-color assay for the specific detection of the A-to-T tranversion in codon 6 of the beta-globin gene, responsible for sickle cell anemia. Both real-time genotyping assays were evaluated by comparing the performance of our method to that of a reference method and in both cases, we found a 100% concordance. This approach will be useful for research and molecular diagnostic laboratories in situations in which the specificity provided by oligonucleotide DNA probes is insufficient to discriminate between two DNA sequences that differ by only one nucleotide.

Factor V Leiden mutation in pregnancy

Normal maternal adaptation to pregnancy significantly increases the risk for thrombus formation. Inherited thrombophilias further increase risk for deep venous thrombosis and adverse outcome in pregnancy. Factor V Leiden mutation is the most common inherited thrombophilia, occurring in approximately 5% of the White and 1% of the Black populations. Nurses should be knowledgeable about screening for and diagnosis of factor V Leiden mutation, risk reduction counseling, recommended care of the affected patient, and implications of anticoagulant therapy during the perinatal period.

Advances in preconception genetic counseling

Preconception counseling offers couples contemplating pregnancy the opportunity to identify and reduce potential pregnancy risks, plan care for known risks, and establish early prenatal care. The goal of preconception counseling is to promote physically and emotionally healthy parents in an attempt to ensure optimal prenatal, intrapartum, and postpartum maternal and fetal health. The advantages of addressing these issues prior to conception include the opportunity of giving recurrence or occurrence risk information for informed decision regarding pregnancy, the accessibility of more reproductive options such as preimplantation genetic diagnosis, and the opportunity to make lifestyle, medical, and behavior alterations for optimal maternal and fetal outcome. This article will discuss advances and updates in preconception genetic counseling including risk assessment and potential intervention for concerns identified through evaluation of family history, ethnicity, maternal age, medical and obstetric history, and associated psychosocial and nursing implications. Significant advances have emerged in the areas of cystic fibrosis carrier screening, first trimester screening, preimplantation genetic diagnosis, and detection and treatment of maternal thrombophilia.

The relationship between FV Leiden and pulmonary embolism

Pulmonary embolism (PE) is one of the leading causes of in-patient hospital deaths. As a consequence, the identification of hemostatic variables that could identify those at risk would be important in reducing mortality. It has previously been thought that deep vein thrombosis and PE are a single disease entity and would, therefore, have the same risk factors. This view is changing, however, with the realization that the prevalence of FV Leiden, a recognized genetic risk factor for deep vein thrombosis, may be a 'milder' genetic risk factor for PE. These observations suggest that PE is not only associated with a different set of risk factors, but may be reflective of a different clot structure.

Vena cava thrombosis associated with nephrotic syndrome in the puerperal gestational cycle

CONTEXT

The puerperal gestational cycle is accompanied by a state of physiological hypercoagulability. Thromboembolic phenomena may occur at this time.

OBJECTIVE

To report on a clinic case involving a patient that presented a family history of thromboembolism and developed deep vein thrombosis in a lower limb and vena cava thrombosis during the puerperal gestational cycle, displaying nephrotic syndrome as the main complication.

DESIGN

Case report.