The U.S. Thrombosis and Hemostasis Centers pilot sites program

Neuraxial and peripheral nerve blocks in patients taking anticoagulant or thromboprophylactic drugs: challenges and solutions

Incidence of hemorrhagic complications from neuraxial blockade is unknown, but classically cited as 1 in 150,000 epidurals and 1 in 220,000 spinals. However, recent literature and epidemiologic data suggest that for certain patient populations the frequency is higher (1 in 3,000). Due to safety concerns of bleeding risk, guidelines and recommendations have been designed to reduce patient morbidity/mortality during regional anesthesia. Data from evidence-based reviews, clinical series and case reports, collaborative experience of experts, and pharmacology used in developing consensus statements are unable to address all patient comorbidities and are not able to guarantee specific outcomes. No laboratory model identifies patients at risk, and rarity of neuraxial hematoma defies prospective randomized study so “patient-specific” factors and “surgery-related” issues should be considered to improve patient-oriented outcomes. Details of advanced age, older females, trauma patients, spinal cord and vertebral column abnormalities, organ function compromise, presence of underlying coagulopathy, traumatic or difficult needle placement, as well as indwelling catheter(s) during anticoagulation pose risks for significant bleeding. Therefore, balancing between thromboembolism, bleeding risk, and introduction of more potent antithrombotic medications in combination with regional anesthesia has resulted in a need for more than “consensus statements” to safely manage regional interventions during anticoagulant/thromboprophylactic therapy.

Whole blood gene expression profiles distinguish clinical phenotypes of venous thromboembolism

INTRODUCTION

Recurrent venous thromboembolism (VTE) occurs infrequently following a provoked event but occurs in up to 30% of individuals following an initial unprovoked event. There is limited understanding of the biological mechanisms that predispose patients to recurrent VTE.

OBJECTIVES

To identify whole blood gene expression profiles that distinguished patients with clinically distinct patterns of VTE.

PATIENTS/METHODS

We studied 107 patients with VTE separated into 3 groups: (1) 'low-risk' patients had one or more provoked VTE; (2) 'moderate-risk' patients had a single unprovoked VTE; (3) 'high-risk' patients had ≥2 unprovoked VTE. Each patient group was also compared to twenty-five individuals with no personal history of VTE. Total RNA from whole blood was isolated and hybridized to Illumina HT-12V4 Beadchips to assay whole genome expression.

RESULTS

Using class prediction analysis, we distinguished high-risk patients from low-risk patients and healthy controls with good receiver operating curve characteristics (AUC=0.81 and 0.84, respectively). We also distinguished moderate-risk individuals and low-risk individuals from healthy controls with AUC's of 0.69 and 0.80, respectively. Using differential expression analysis, we identified several genes previously implicated in thrombotic disorders by genetic analyses, including SELP, KLKB1, ANXA5, and CD46. Protein levels for several of the identified genes were not significantly different between the different groups.

CONCLUSION

Gene expression profiles are capable of distinguishing patients with different clinical presentations of VTE, and genes relevant to VTE risk are frequently differentially expressed in these comparisons.

Differences in thrombotic risk factors in black and white women with adverse pregnancy outcome

INTRODUCTION

Black women have an increased risk of adverse pregnancy outcomes and the characteristics of thrombotic risk factors in this population are unknown. The objective of this study was to examine the racial differences in thrombotic risk factors among women with adverse pregnancy outcomes.

METHODS

Uniform data were collected in women with adverse pregnancy outcomes (pregnancy losses, intrauterine growth restriction (IUGR), prematurity, placental abruption and preeclampsia) referred to Thrombosis Network Centers funded by the Centers for Disease Control and Prevention (CDC).

RESULTS

Among 343 white and 66 black women seen for adverse pregnancy outcomes, protein S and antithrombin deficiencies were more common in black women. The prevalence of diagnosed thrombophilia was higher among whites compared to blacks largely due to Factor V Leiden mutation. The prevalence of a personal history of venous thromboembolism (VTE) did not differ significantly by race. A family history of VTE, thrombophilia, and stroke or myocardial infarction (MI) was higher among whites. Black women had a higher body mass index, and a higher prevalence of hypertension, while the prevalence of sickle cell disease was approximately 27 fold higher compared to the general US black population.

CONCLUSIONS

Thrombotic risk factors differ significantly in white and black women with adverse pregnancy outcomes. Such differences highlight the importance of considering race separately when assessing thrombotic risk factors for adverse pregnancy outcomes.

Characteristics of abdominal vein thrombosis in children and adults

The demographic and clinical characteristics of adults and children with lower extremity deep-vein thrombosis and/or pulmonary embolism (LE DVT/PE) may differ from those with abdominal vein thrombosis (abdominal VT). Abdominal VT can be a presenting sign of an underlying prothrombotic state, and its presence in the setting of known disease might have prognostic implications different from LE DVT/PE. This study describes clinical presentations of abdominal VT compared to LE DVT/PE in adults and children. We analysed prospectively-collected data from consecutive consenting patients enrolled in one of seven Centers for Disease Control and Prevention (CDC) funded Thrombosis and Hemostasis Network Centers from August 2003 to April 2011 to compare the demographic and clinical characteristics of adults and children with abdominal VT. Both adults and children with abdominal VT tended to be younger and have a lower body mass index (BMI) than those with LE DVT/PE. Of patients with abdominal VT, children were more likely to have inferior vena cava (IVC) thrombosis than adults. For adults with venous thromboembolism (VTE), relatively more women had abdominal VT than LE DVT/PE, while the proportions with LE DVT/PE and abdominal VT by sex were similar in children. Children with abdominal VT were more likely to have diagnosed inherited thrombophilia, while trauma was more common in children with LE DVT/PE. In conclusion, both children and adults with abdominal VT were younger with a lower BMI than those with LE DVT/PE. Significant differences exist between children and adults in respect to abdominal VT compared to LE DVT/PE.

Developing a public health research agenda for women with blood disorders

Bleeding and clotting in women is an issue that directly affects the life of every woman, child, and family worldwide. This article summarizes recent activities undertaken by the Division of Blood Disorders (DBD) at the Centers for Disease Control and Prevention (CDC) to identify risk factors through evidence-based research and surveillance to prevent complications of blood disorders in women. Specific focus is given to our efforts to improve early identification and diagnosis of blood disorders among women, improve our understanding of maternal and infant outcomes, and develop surveillance systems to monitor the prevalence and incidence of these events.

Whole blood gene expression analyses in patients with single versus recurrent venous thromboembolism

INTRODUCTION

Venous thromboembolism may recur in up to 30% of patients with a spontaneous venous thromboembolism after a standard course of anticoagulation. Identification of patients at risk for recurrent venous thromboembolism would facilitate decisions concerning the duration of anticoagulant therapy.

OBJECTIVES

In this exploratory study, we investigated whether whole blood gene expression data could distinguish subjects with single venous thromboembolism from subjects with recurrent venous thromboembolism.

METHODS

40 adults with venous thromboembolism (23 with single event and 17 with recurrent events) on warfarin were recruited. Individuals with antiphospholipid syndrome or cancer were excluded. Plasma and serum samples were collected for biomarker testing, and PAXgene tubes were used to collect whole blood RNA samples.

RESULTS

D-dimer levels were significantly higher in patients with recurrent venous thromboembolism, but P-selectin and thrombin-antithrombin complex levels were similar in the two groups. Comparison of gene expression data from the two groups provided us with a 50 gene probe model that distinguished these two groups with good receiver operating curve characteristics (AUC 0.75). This model includes genes involved in mRNA splicing and platelet aggregation. Pathway analysis between subjects with single and recurrent venous thromboembolism revealed that the Akt pathway was up-regulated in the recurrent venous thromboembolism group compared to the single venous thromboembolism group.

CONCLUSIONS

In this exploratory study, gene expression profiles of whole blood appear to be a useful strategy to distinguish subjects with single venous thromboembolism from those with recurrent venous thromboembolism. Prospective studies with additional patients are needed to validate these results.

Comparison of characteristics from White- and Black-Americans with venous thromboembolism: a cross-sectional study

When compared with Whites, Black-Americans may have a 40% higher incidence venous thromboembolism (VTE) incidence. However, whether other VTE characteristics and risk factors vary by race is uncertain. To compare demographic and baseline characteristics among White- and Black-Americans with VTE, we used data prospectively collected from consecutive consenting adults enrolled in seven Centers for Disease Control (CDC) Thrombosis and Hemostasis Centers from August 2003 to March 2009. These characteristics were compared among Whites (n = 2002) and Blacks (n = 395) with objectively diagnosed VTE, both overall, and by age and gender. When compared with Whites, Blacks had a significantly higher proportion with pulmonary embolism (PE), including idiopathic PE among Black women, and a significantly higher proportion of Blacks were women. Blacks had a significantly higher mean BMI and a significantly lower proportion with recent surgery, trauma or infection, family history of VTE, and documented thrombophilia (solely from reduced factor V Leiden and prothrombin G20210A prevalence). Conversely, Blacks had a significantly higher proportion with hypertension, diabetes mellitus, chronic renal disease and dialysis, HIV, and sickle cell disease. When compared with White women, Black women had a significantly lower proportion with recent oral contraceptive use or hormone therapy. We conclude that Whites and Blacks differ significantly regarding demographic and baseline characteristics that may be risk factors for VTE. The prevalence of transient VTE risk factors and idiopathic VTE among Blacks appears to be lower and higher, respectively, suggesting that heritability may be important in the etiology of VTE among Black-Americans.

Venous thromboembolism: a public health concern

Venous thromboembolism (VTE), defined as deep vein thrombosis, pulmonary embolism, or both, affects an estimated 300,000-600,000 individuals in the U.S. each year, causing considerable morbidity and mortality. It is a disorder that can occur in all races and ethnicities, all age groups, and both genders. With many of the known risk factors-advanced age, immobility, surgery, obesity-increasing in society, VTE is an important and growing public health problem. Recently, a marked increase has occurred in federal and national efforts to raise awareness and acknowledge the need for VTE prevention. Yet, many basic public health functions-surveillance, research, and awareness-are still needed. Learning and understanding more about the burden and causes of VTE, and raising awareness among the public and healthcare providers through a comprehensive public health approach, has enormous potential to prevent and reduce death and morbidity from deep vein thrombosis and pulmonary embolism throughout the U.S.

Regional anesthesia in the patient receiving antithrombotic or thrombolytic therapy: American Society of Regional Anesthesia and Pain Medicine Evidence-Based Guidelines (Third Edition)

The actual incidence of neurologic dysfunction resulting from hemorrhagic complications associated with neuraxial blockade is unknown. Although the incidence cited in the literature is estimated to be less than 1 in 150,000 epidural and less than 1 in 220,000 spinal anesthetics, recent epidemiologic surveys suggest that the frequency is increasing and may be as high as 1 in 3000 in some patient populations.Overall, the risk of clinically significant bleeding increase with age,associated abnormalities of the spinal cord or vertebral column, the presence of an underlying coagulopathy, difficulty during needle placement,and an indwelling neuraxial catheter during sustained anticoagulation( particularly with standard heparin or low-molecular weight heparin). The need for prompt diagnosis and intervention to optimize neurologic outcome is also consistently reported. In response to these patient safety issues, the American Society of Regional Anesthesia and Pain Medicine (ASRA) convened its Third Consensus Conference on Regional Anesthesia and Anticoagulation. Practice guidelines or recommendations summarize evidence-based reviews. However, the rarity of spinal hematoma defies a prospective randomized study, and there is no current laboratory model. As a result,the ASRA consensus statements represent the collective experience of recognized experts in the field of neuraxial anesthesia and anticoagulation. These are based on case reports, clinical series, pharmacology,hematology, and risk factors for surgical bleeding. An understanding of the complexity of this issue is essential to patient management.

Hospital-Acquired Venous Thromboembolism: A Retrospective Analysis of Risk Factor Screening and Prophylactic Therapy

Purpose

To identify the incidence of hospital-acquired venous thromboembolism (HAVTE), evaluate the VTE risk factor screening, and evaluate the use and effectiveness of prophylactic agents used in HAVTE patients at St Vincent's Medical Center (SVMC).

Methods

The SVMC's database was queried from January 2005 to December 2006 for all the discharges with a secondary diagnosis of deep vein thrombosis (DVT) and/or pulmonary embolism (PE) and patients with a primary diagnosis of DVT and/or PE who were readmitted within 30 days of their previous admission from SVMC.

Results

A total of 421 charts were screened and 91 charts, representing patients with HAVTE, were included. Among these patients, 56% of subjects suffered from a DVT, 31% had a PE, and 13% had both a DVT and PE. Thirty-five percent of the patients' prophylactic therapy was noncompliant with the American College of Chest Physician's (ACCP) 2004 VTE prophylaxis guideline recommendations. Documentation of patient risk factors was present in 8.8% of all the patients with HAVTE. Twenty-one percent of the patients were not prescribed any VTE prophylactic agent, of which 89% qualified for VTE prophylaxis.

Conclusions

The incidence of HAVTE was found to be 2.24 cases per 1000 discharges from SVMC. The prophylactic therapy among the patients with HAVTE was compliant with the ACCP's VTE guideline recommendations in 65% of cases. The documentation of risk factor screening was found to be 8.8%. The current DVT/PE protocol at SVMC needs revision to provide a more consistent assessment of patient risk factor, and implementation of DVT/PE prophylaxis throughout the continuum of care based on the current guidelines.