ALBERT

Description: Background: Compared to Whites, Black-Americans may have a 40% higher incidence of idiopathic VTE. However, whether other VTE characteristics vary by race is uncertain. Objective: To compare demographic and baseline characteristics among White- and Black-Americans with VTE. Methods: Using a standardized data-collection form, demographic and baseline characteristics were prospectively collected from consecutive consenting patients enrolled in seven Thrombosis and Hemostasis Centers from August 2003 to March 2008. For patients with objectively diagnosed VTE, demographic and baseline characteristics were compared among White- and Black-American VTE patients, both overall, and by age and gender. Results: Among 1960 White- and 368 Black-Americans with VTE, compared to Whites, Blacks had significantly less isolated DVT (73.9% vs. 86.5%, p

Description: Abstract 150 Background: While bivariate interactions between Factor V Leiden, prothrombin G20201A and hereditary deficiency of antithrombin, protein C and protein S compound VTE risk, whether other gene-gene interactions are associated with VTE is largely unknown. Objective: To test gene-gene interactions for an association with VTE. Methods: Cases (n=1004) were Mayo Clinic European-American patients of non-Hispanic ancestry with objectively-diagnosed VTE in the absence of active cancer, venous catheter or antiphospholipid antibodies. Controls (n=1066) were Mayo Clinic outpatients without VTE who were frequency-matched on case age, gender, race, MI/stroke status and state of residence. We selected candidate genes relevant to the anticoagulant, procoagulant, fibrinolytic and innate immunity pathways, focusing on platelet, monocyte, neutrophil and endothelial cell agonists, receptors, ligands, signal transduction and adhesion molecules, granule contents and effectors; plasma proteases and inhibitors; matrix metalloproteases; inflammatory cytokines and receptors; estrogen, progesterone and androgen receptors; co-regulators and enzymes related to estrogen metabolism; important enzymes for catechol, homocysteine, thromboxane A2 and prostacyclin biosynthesis and metabolism; and HMG CoA reductase. For these genes (n=780), we selected all non-synonymous coding single nucleotide polymorphisms (SNPs) with minor allele frequency ≥0.5%; the remaining SNPs were selected using an LD tagging algorithm (Carlson et al. AJHG 2004); 558 ancestry-informative markers were also included (total n=13,237 SNPs). Leukocyte genomic DNA was genotyped using a custom Illumina Infinium iSelect chemistry and platform, including appropriate controls. For these analyses, all pairwise SNP-SNP interactions for 12,313 SNPs were tested using logistic regression. In addition, we tested all Factor V Leiden -, prothrombin G20210A - and ABO non-O blood group - SNP interactions. Results: The mean ± SD case and control ages were 55.3 ± 16.4 and 56.5 ± 15.9 years, respectively, and 51% were female. Analysis of ancestry-informative markers gave no evidence of population stratification. Among almost 76 million pairwise interactions tested, 504, 44 and 8 SNP-SNP interactions reached p-values ≤ 1E-5, 1E-6, and 1E-7 respectively; none reached the Bonferroni statistical significance threshold (≤ 6.6E-10). The gene-gene pairwise interactions with p-values ≤ 1E-7 included: Leptin receptor - Estrogen receptor 1, α1 Antichymotrypsin - β2 glycoprotein 1, CRADD(caspace) - B1 Bradykinin receptor, ILF10 - Prolactin receptor and GFRA2(TGFβ neurotrophic factor receptor) - Bactericidal permeability-increasing protein. Gene-gene pairwise interactions with the lowest p-value for Factor V Leiden -, prothrombin G20210A - and ABO non-group O - were Protein kinase C beta (2.1E-5), von Willebrand Factor (7.6E-4) and Phospholipase C gamma-2 (6.7E-4), respectively. Conclusion: Pairwise gene-gene interaction analyses suggest potential associations between VTE and novel genes and gene pathways. These potential associations require confirmation in future replication studies. Disclosures: No relevant conflicts of interest to declare.

Description: Accurate measurement of plasma von Willebrand factor (VWF) activity is essential for the laboratory diagnosis and treatment monitoring of von Willebrand disease (VWD). Currently available VWF activity assays include VWF ristocetin cofactor activity by manual light transmission platelet aggregometry (VWF:RCo–Agg) or flow cytometry (VWF:RCo–FL), collagen I and III binding activity (VWF:Co–I and –III) (Technozym), and platelet activity by latex agglutination (VWF:Lx) (Instrumental Laboratory). In this study we evaluated and compared the accuracy and precision of these 5 assay methods. Plasma samples from 11 normal donors and 41 patients categorized as type 1 (n=20) or type 2 (n=21) VWD based on clinical evaluation, fVIII:C activity, VWF:RCo–Agg, VWF antigen (VWF:Ag) level and plasma VWF multimer analysis by agarose gel electrophoresis were assayed for VWF activity by VWF:RCo–FL, VWF:Co–I, VWF:Co–III and VWF:Lx methods. The VWF:Ag/VWF activity ratio by VWF activity assay method was calculated for each sample. For normal donors and type I VWD patients, VWF:RCo–FL and VWF:Lx correlated well with VWF:RCo–Agg (R2=0.87, and 0.97, respectively), while VWF:Co–I and –III were lower compared to VWF:RCo-Agg. For type 2 VWD patients, different VWF:Ag/VWF activity ratio cutoffs (range 0.3–0.7) were used (Figure). Both VWF:RCo–Agg and –FL were sensitive (95%) and specific (97%) for type 2 VWD while the VWF:Lx was slightly less sensitive (81%) but was very specific (100%). VWF:Co–I and –III were the least sensitive (

Description: Introduction: Diabetes mellitus is often cited as a VTE risk factor. However, persons with diabetes are frequently hospitalized for medical illness or undergo surgery, both major VTE risk factors. Thus, the association of VTE with diabetes independent of surgery or hospitalization is uncertain. Methods: Using longitudinal, population-based Rochester Epidemiology Project resources, we identified all Olmsted County, MN residents who met objective criteria for incident VTE over the 25-year period, 1976–2000 (n=1922), and one to two controls per case, matched on age, gender, Olmsted County residency, and length of medical history (n=2115). For cases and controls, we reviewed their complete medical history in the community for baseline characteristics previously identified as independent VTE risk factors, including clinically-diagnosed diabetes mellitus. We tested diabetes as a potential VTE risk factor both alone and after adjusting for other baseline characteristics, and in the subset of cases with idiopathic VTE, using conditional logistic regression. Results: Among all cases and controls, 231 (12%) and 199 (9.4%) had diabetes, respectively. Univariately, diabetes was associated with overall VTE (odds ratio [OR]=1.32; 95% CI: 1.07, 1.62; p=0.009). However, after controlling for body mass index (OR=1.04, p

Description: Introduction: Assays of plasma von Willebrand factor (VWF) ristocetin cofactor activity (VWF:RCo) are essential for the laboratory diagnosis of von Willebrand disease (VWD). However, the current manual platelet aggregation/aggregometry method has relatively poor operating characteristics. Our goal was to develop a simple, accurate and sensitive platelet based assay. Methods: VWF protein from normal or patient plasma was first captured on the polyclonal anti-VWF antibody coated plastic plate surface. VWF:RCo activity was assayed by the binding of mitotracker (a red fluorochrome)-labeled, formalin-fixed normal platelets in the presence of ristocetin (1mg/ml) and under agitation (200 rpm by vortex). The fluorescence from the bound platelets, measured by a fluorescence microtiter plate reader (Fluor4000, BioRad), was related to the calibrator plasma signal (6∼150% or IU/dL), and reported as % or IU/dL. We tested plasma samples from normal donors (n=16) and known VWD patients (type 1, n=6; type 2, n=9) based on clinical history and levels of plasma VWF antigen (VWF:Ag), VWF:RCo activity (manual platelet aggregation/aggregometry method), factor VIII activity and VWF multimer analysis. Results: For both normal donors and VWD patients, VWF:RCo activities by the plate assay vs. manual platelet aggregation/aggregometry method correlated closely (R2=0.84), and VWF:RCo/VWF:Ag ratios did not differ significantly. Platelet binding to VWF-coated plastic wells is both VWF specific and ristocetin dependent. Conclusions: Although this new platelet based VWF:RCo plate assay is still being optimized and validated, the preliminary data suggest that it is simple, accurate and sensitive.

Description: Background: Hematological cancer patients are at an increased risk for VTE (RR range = 12–32). However, whether VTE risk among such patients can be further stratified is uncertain. Objective: To test hematological cancer type, stage, stage progression and chemotherapy as potential risk factors for VTE among active hematological cancer patients after controlling for other previously-identified VTE risk factors. Methods: Using the resources of the Rochester Epidemiology Project, Mayo Clinic Master Diagnostic Index and Mayo Clinic Tumor Registry, we identified all Olmsted County, MN residents with active hematological cancer over the 28-year period, 1973–2000. From this prevalence cohort, we identified 86 patients with no prior VTE (controls) who were matched on age and date of hematological cancer diagnosis to 86 hematological cancer patients with incident VTE over the same time frame (cases). For all cases and controls, we reviewed the complete medical records in the community for baseline and hematological cancer-related characteristics. Hematological cancers were re-staged at the dates of the cancer and VTE diagnosis. We tested these characteristics as potential risk factors for VTE in active hematological cancer using conditional logistic regression. Results: In an initial multivariate analysis that included body mass index (BMI), hospitalization, and any infection or central venous catheter placement within 90 days prior to the VTE event, VTE was significantly associated with hospitalization (OR=6.70; p

Description: Menorrhagia is a common clinical problem among reproductive age women and annually 5% of reproductive age women seek medical attention, usually with gynecologists and other primary care physicians, for this symptom. Since underlying bleeding disorders are common in women presenting with menorrhagia, and referral for comprehensive hemostatic testing of substantial numbers of women with otherwise unexplained menorrhagia is problematic from the public health and cost perspective, a short, easy-to-administer screening tool comprised of 8 questions for identifying women with menorrhagia for hemostatic evaluation was previously developed (Am J Ob Gyn2008;198:e1–163e8). In the present study, the validity of the screening tool was evaluated in a multi-site, prospectively recruited cohort of women with menorrhagia. 232 women with menorrhagia age 18 and older with a pictorial blood assessment chart (PBAC) score 〉 100 were recruited from 5 US centers as potential subjects for a prospective cross-over study for evaluation of intranasal DDAVP versus tranexamic acid. All subjects underwent comprehensive laboratory testing for bleeding disorders, including VWF, platelet aggregation/ATP release, and factor assays. Study participants were administered a questionnaire which included the 8 screening tool questions in 4 categories, including history of duration and severity of menorrhagia, anemia treatment, excessive bleeding with hemostatic challenges, and family diagnosis of bleeding disorder. A screening tool was considered positive if there was a positive response for any of the questions in the four categories. Sensitivity of the screening tool with 95% confidence interval was calculated for bleeding disorders and also separately for low VWF (ristocetin cofactor 〈 50%), and platelet function defects.217 women with menorrhagia including 78% white and 16% black women with complete data were evaluated. In this population, a positive screening tool had a sensitivity of 89% (95% CI, 83–93) for bleeding disorders, 89% for platelet function defects (95% CI, 82–94), and 73% for low VWF (95% CI, 39–94). The sensitivity for bleeding disorders was 87% (95% CI, 79–92) among white women and 94% (95% CI, 79–99) among black women. Adding a PBAC score 〉 185 increased the sensitivity of the screening tool for bleeding disorders to 95% (95% CI, 90–98). Using a multi-site US population of adult women with menorrhagia, this study confirms the benefit of a short screening tool to assist primary care physicians in the selection of women with menorrhagia to refer for comprehensive hemostatic testing and evaluation. population of adult women with menorrhagia, this study confirms the benefit of a short screening tool to assist primary care physicians in the selection of women with menorrhagia to refer for comprehensive hemostatic testing and evaluation.

Description: Background While consensus guidelines regarding VTE prophylaxis for hospital inpatients have been available for more than 15 years, the number of US inpatients who are potentially eligible for prophylaxis is unknown. Such data are required for estimating the potential costs and benefits of prophylaxis in reducing VTE incidence. Objective To estimate the number of Y2002 US acute-care hospital inpatients who are potentially eligible for VTE prophylaxis. Methods We applied the 7th (2004) American College of Chest Physician (ACCP) Consensus Conference VTE prophylaxis guidelines (Geerts et al. Chest2004;126:338S–400S) to inpatients with hospital discharge International Classification of Disease (ICD-9) codes for major surgery or medical illness identified from the Healthcare Utilization and Cost Database (HCUP), a national acute-care hospital database supported by the US Agency for Health Care Quality Research. Results Of a total of 37.8 million inpatients discharged from US acute-care hospitals in Y2002, 13.4 million (35%) met ACCP guideline criteria for VTE prophylaxis (Table). Table. Inpatients Discharged from US Acute-Care Hospitals with ACCP Guideline Defined Risk of VTE in Y2002 Surgical VTE Risk N Highest risk surgery 744,465 High risk surgery 3,031,318 Moderate risk surgery 2,019,696 Surgical subtotal 5,795,479 Medical VTE Risk N Heart failure 1,867,576 Cancer 1,017,356 Stroke 515,370 Other medical conditions 4,196,343 Medical subtotal 7,596,645 Grand Total 13,392,124 Among the 37.8 million Y2002 discharged inpatinets, 7.7 million were defined by HCUP criteria as having had a major operative procedure. When ACCP surgical risk criteria were applied to this population, 1.9 (25%) were at low VTE risk, while 5.8 million (75%) were at moderate (26%), high (39%) or highest (10%) VTE risk. Among the patients without a major operative procedure, 7.6 million met the ACCP criteria for VTE prophylaxis based on medical illness risk factors. Conclusions In total, 13.4 million US residents meet ACCP criteria for VTE prophylaxis annually due to hospitalization for either major surgery or medical illness. Given that almost 60% of all VTE events occurring in the community are related to recent acute-care hospitalization, providing universal, safe and effective VTE prophylaxis to this population affords an important opportunity to significantly reduce the incidence of VTE. These data provide support for developing and monitoring compliance with hospital-wide guidelines for VTE prevention.

Description: Background: Venous stasis syndrome (VSS) is a relatively common long-term sequelae of deep vein thrombosis (DVT), although it frequently is noted in individuals with no prior history of DVT. Objective: To evaluate whether: (1) venous stasis syndrome (VSS) is associated with a prior history of DVT; (2a) venous outflow obstruction (VOO) and/or (2b) venous valvular incompetence (VVI) are associated with DVT; and (3) VSS is associated with VVI and/or VOO. Design: Case-control study nested within a population-based inception cohort study. Population: 230 residents of Olmstead County, MN (OCM) with a first lifetime VTE over the 25-year period, 1966 – 1990 (cases), and 135 age, gender and year of incident VTE-matched OCM residents without prior history of VTE (controls). Measurements: Physical examination and patient questionnaire for symptoms or signs of VSS, and strain gauge outflow plethysmography, continuous wave venous Doppler ultrasound, and passive venous drainage and refill testing for VOO and VVI performed between 1996 – 1998. Results: Of the 365 study participants, 43 (12%) had VOO, 136 (37%) had VVI, and 265 (73%) had VSS. In multivariate logistic regression analyses: (1) age at the follow-up visit [OR Δper 10 years: 1.70 (1.41, 2.04)], prior DVT in the affected limb [OR: 4.03 (2.32, 7.01)], and presence of prior varicose veins [OR: 4.36 (1.84, 10.31)] were significantly associated with VSS; (2a) age at the follow-up visit [OR Δper 10 years (95% CI): 1.84 (1.39, 2.44)] and prior DVT in the affected limb [OR: 5.01 (2.61, 9.63)] were significantly associated with VOO; (2b) prior DVT in the affected limb (OR: 3.91 (2.56, 5.97)], presence of prior varicose veins [OR: 2.19 (1.32, 3.63)] and symptoms of VSS prior to incident DVT [OR: 3.42 (1.46, 8.00)] significantly increased the odds for VVI; and (3) VOO (p=0.004) and VVI (p

Description: Background The total annual number of VTE events and related deaths in the US is unknown, largely because the complete spectrum of disease (including asymptomatic events and sudden deaths) occurring in the community is under-recognized. Objective To estimate the total annual number of non-fatal and fatal deep vein thrombosis (DVT) and pulmonary embolism (PE) events (incident and recurrent) in the US. Methods We developed an incidence-based model that included both hospital- and community-acquired VTE events as well as death from recognized and unrecognized VTE. We estimated the annual number of community-acquired events using the average age-, sex-, and event-specific incidence rates in Olmsted County, MN (1966–1990) and Y2000 US census data. We estimated the annual number of hospital-acquired events using patient age and Y2002 International Classification of Disease (ICD-9) discharge diagnosis codes for major surgery types or acute medical illnesses within the Healthcare Utilization and Cost Database, which includes major discharge diagnoses from all US acute-care hospitals. Patients were included in the hospital model if they were deemed at risk of VTE according to current American College of Chest Physicians definitions. The hospital at-risk population was divided into categories according to type of surgery or medical diagnosis on admission. We estimated the annual number of VTE events based on the published probability of VTE with and without prophylaxis, and US prophylaxis rates, by risk group. Fatal and recurrent events were estimated based on published data. The effects of VTE and prophylaxis rate uncertainty on our estimates were tested using sensitivity analyses. Results The estimated total annual number of symptomatic VTE events in the US exceeded 600,000, (DVT, n=376,365; PE, n=237,058. Table). Table. Annual Number of Non-Fatal and Fatal, Community- and Hospital-Acquired Symptomatic VTE Events in the US Event Type Community Hospital Total Non-Fatal ---------n---------- DVT 108,240 268,125 376,365 PE 85,358 151,700 237,058 Total 193,598 419,825 613,423 Fatal DVT 649 1,609 2,258 PE 105,902 188,210 294,112 Total 106,550 189,819 296,370 VTE-related deaths were estimated at 296,370 annually. Of these deaths, 21,223 (7%) patients were diagnosed with VTE and treated, 101,032 (34%) were sudden fatal PE and 174,115 (59%) followed undetected PE. Approximately two-thirds of symptomatic VTE events were hospital-acquired and one-third were community-acquired. Conclusions Our study confirms that VTE is a major US health problem. Given that effective VTE prophylaxis and expert consensus prophylaxis guidelines are widely available, these data suggest that universal, safe and effective prophylaxis could significantly reduce US VTE incidence and related deaths. Future studies should address the impact of universal VTE prophylaxis on VTE incidence and survival.