Clinical probability assessment and D-dimer determination in patients with suspected deep vein thrombosis, a prospective multicenter management study

Objectives

To investigate the reliability of a combined strategy of clinical assessment score followed by a local D-dimer test to exclude deep vein thrombosis. For comparison D-dimer was analysed post hoc and batchwise at a coagulation laboratory.

Design

Prospective multicenter management study.

Setting

Seven hospitals in southern Sweden.

Subjects

357 patients with a suspected first episode of deep vein thrombosis (DVT) were prospectively recruited and pre-test probability score (Wells score) was estimated by the emergency physician. If categorized as low pre-test probability, D-dimer was analysed and if negative, DVT was considered to be ruled out. The primary outcome was recurrent venous thromboembolism (VTE) during 3 months of follow up.

Results

Prevalence of DVT was 23.5% (84/357). A low pre-test probability and a negative D-dimer result at inclusion was found in 31% (110/357) of the patients of whom one (0.9%, [95% CI 0.02-4.96]) had a VTE at follow up. Sensitivity, specificity, negative predictive value and negative likelihood ratio for our local D-dimer test in the low probability group were 85.7%, 74.5%, 98.2%, and 0,19 respectively compared to 85.6%, 67,6%, 97.9% and 0,23 using batchwise analysis at a coagulation laboratory.

Conclusion

Pre-test probability score and D-dimer safely rule out DVT in about 30% of outpatients with a suspected first episode of DVT. One out of 110 patients was diagnosed with DVT during follow up. No significant difference in diagnostic performance was seen between local D-dimer test and the post hoc batch analysis with the same reagent in the low probability group.     

Has the incidence of deep vein thrombosis in patients undergoing total hip/knee arthroplasty changed over time? A systematic review of randomized controlled trials

Background

There is a perception in the orthopaedic and thromboembolism community that the incidence of deep vein thrombosis (DVT) has decreased in patients undergoing total knee arthroplasty (TKA) or total hip arthroplasty (THA).

Objectives

To assess the incidence of DVT with warfarin thromboprophylaxis over time in patients undergoing elective TKA or THA.

Methods

The MEDLINE, EMBASE, and Cochrane Library databases were searched to October 2006, supplemented by a manual search of reference lists. Two reviewers independently extracted data on study characteristics, quality and the frequency of total, symptomatic and proximal DVT.

Results

Fourteen studies (4,423 patients) were included. Total and proximal DVT after TKA declined over time (r = − 0.75, p = 0.031; r = − 0.86, p = 0.007 respectively). Total and proximal DVT after THA did not change. The risk of developing DVT after TKA was significantly higher than after THA (OR 1.85, 95% CI 1.6 - 2.14; p < 0.0001). The risk of developing symptomatic DVT after THA was significantly higher than after TKA (OR 2.18, 95% CI 1.11 - 4.27; p = 0.012).

Conclusions

The incidence of DVT in patients undergoing elective TKA appears to have declined in patients receiving warfarin thromboprophylaxis.     

Incidence and predictive factors of symptomatic thrombosis related to peripherally inserted central catheters in chemotherapy patients

Introduction

The incidence of symptomatic catheter-related deep vein thrombosis (DVT) in cancer patients remains unclear and there is a lack of reliable data on the risk factors of PICC-related DVT.

Materials and Methods

We performed a retrospective cohort study of consecutive cancer patients who received an ultrasound guided PICC line for the administration of chemotherapy. Univariable and multivariable logistic regression analyses were performed to identify risk factors for symptomatic PICC-related DVT.

Results

In total, 340 cancer patients obtained PICC lines for the administration of chemotherapy. Of these patients, 19 (5.6%; 95% CI: 3.6-8.6) developed symptomatic PICC-related DVT. Factors previously associated with catheter-related DVT, including side of catheter placement, lumen size, tip location, need for repositioning, and number of insertion attempts, were not significant determinants in our analysis. Patients with diabetes were three times more likely to develop PICC-related DVT (OR 3.0, p = 0.039), while the presence of COPD and metastatic cancer also increased the odds (OR 3.3, p = 0.078 and OR 2.3, p = 0.083 respectively). Diabetes remained a significant risk factor after adjustment for effect of metastases and COPD (OR 3.175, p = 0.039). Further, the presence of metastases was a significant predictor (OR 3.34, p = 0.024) in our multivariable model.

Conclusions

Symptomatic PICC-related DVT are frequent in cancer patients receiving chemotherapy. Previously described factors associated with catheter-related thrombosis were not predictive of PICC-related DVT in our study. Diabetes, advanced disease and COPD appear to increase the risk of developing PICC-related DVT in chemotherapy patients.     

Prevalence of genetic mutations in protein S, protein C and antithrombin genes in Japanese patients with deep vein thrombosis

Introduction

Genetic deficiencies of PROS1, PROC, and SERPINC1 (antithrombin) are risk factors for deep vein thrombosis (DVT). Diagnosis of the inherited deficiencies of these three genes is sometimes difficult because of the phenotypic variability. This study was undertaken to reveal the frequency of nonsynonymous mutations of these three genes in Japanese DVT patients.

Patients/Methods

One hundred seventy-three DVT patients were registered by the Sub-group of Blood Coagulation Abnormality, from the Study Group of Research on Measures for Intractable Diseases. We sequenced the entire coding regions of the three genes in all DNA samples and identified the nonsynonymous mutations.

Results and Conclusions

For PROS1 we identified 15 nonsynonymous mutations in 28 DVT patients; for PROC, 10 nonsynonymous mutations in 17 patients; and for SERPINC1, 13 nonsynonymous mutations in 14 patients. Five patients had two mutations in PROS1 and PROC, and all of them had PROS1 K196E mutation. We previously identified one patient with a large PROS1 gene deletion. Thus, 55 out of 173 patients (32%) carried at least one genetic defect in the three genes. The PROS1 K196E mutation found in 15 Japanese DVT patients was the most prevalent. Mutations of PROC K193del and V339M were the second, each found in four patients. Our data suggested that the PROC K193del mutation caused the loss of the anticoagulant activity but not the amidolytic activity. Our effort is the first DNA resequencing study to identify the genetic variations in DVT patients without any consideration of their plasma activities and antigens. To minimize selection bias in a future evaluation of the contribution of genetic deficiency to DVT, we must recruit patients consecutively.     

Accuracy and usefulness of a clinical prediction rule and D-dimer testing in excluding deep vein thrombosis in cancer patients

Introduction

Deep vein thrombosis (DVT) can be safely and reliably excluded in patients with a low clinical probability and a negative D-dimer result but the accuracy and utility of such a strategy is less certain in cancer patients. We sough to compare the performance of the Wells pretest probability (PTP) model and D-dimer testing between patients with and without cancer and to examine the utility of the two PTP model classification schemes (low/moderate/high versus unlikely/likely) in excluding DVT in patients with cancer.

Materials and methods

Pooled analysis of databases from three prospective diagnostic studies evaluating consecutive outpatients with suspected DVT.

Results

A total of 2696 patients were evaluated. DVT was diagnosed in 403 (15%) patients overall and in 83 of 200 (41.5%) cancer patients. The PTP distribution and the prevalence of DVT in each PTP category were significantly different between patients with and without cancer, regardless of the classification used (p < 0.01). In patients with cancer, the negative predictive values of a low or unlikely PTP score in combination with a negative D-dimer result were 100% (95% CI 69.8%-100%) and 100% (95% CI 82.8%-96.6%), respectively. However, the specificities ranged from 46.2% (95%CI 27.1%-66.3%) to 57.1% (95%CI 41.1%-71.9%). Further testing was required in 94% of cancer patients using the low/moderate/high PTP classification and in 88% using the unlikely/likely stratification.

Conclusions

As in patients without cancer, the combination of a low or unlikely PTP with a negative D-dimer result can exclude DVT in patients with cancer. However, this strategy has limited utility because very few cancer patients present with this combination.     

Low level of factor V is associated with development of deep-vein thrombosis in Japanese patients

Background

Factor V, having two functions (procoagulant and anticoagulant), is a key factor in blood coagulation, and low plasma levels of factor V may be a risk factor for thrombosis.

Objective

The levels of plasma factor V antigen (FV:Ag), and the phospholipid binding capability of Factor V (FV:PL-bound) were evaluated in patients with deep-vein thrombosis (DVT).

Methods

Levels of FV:Ag, and FV:PL-bound were expressed as a percentage of the normal level found in pooled plasma from control subjects. One hundred and twenty-three Japanese patients with deep-vein thrombosis (DVT) were included, with 100 age and sex-matched healthy control subjects.

Results

The FV:Ag, and FV:PL-bound values were significantly lower in DVT patients than in healthy subjects (p < 0.05 and p < 0.005, respectively). Among the 123 patients, 30 for FV:Ag (24.4%), and 32 for FV:PL (26%) had less than the arbitrary cutoff point (set at the 5th percentile of the value for FV:Ag and FV:PL-bound from healthy subjects), and the odds ratios (ORs) were 6.1 (95% confidence interval [CI], 2.3-16.5) and 6.7 (95%CI, 2.5-17.9), respectively. When patients with a deficiency of natural anticoagulants (antithrombin, protein C, and protein S) were excluded from the analysis, the ORs increased for all patients (6.6 for FV:Ag (95%CI, 2.4-18.3) and 7.4 for FV:PL-bound (95%CI, 2.7-20.3). Moreover, twenty-one (17%) of the 123 DVT patients, and 1 (1%) of 100 control subjects had values below the cutoff points for both FV:Ag and FV:PL-bound, and the OR was 21.6 (95%CI, 2.85-163.1).

Conclusions

These results suggest that low levels of factor V are associated with development of DVT, and may be a predictor for DVT.     

Incidence and characteristics of asymptomatic distal deep vein thrombosis unexpectedly found at admission in an Internal Medicine setting

Introduction

Lower limb deep vein thrombosis (DVT) is the most frequent clinical manifestation of venous thromboembolism (VTE) and can involve proximal or distal veins. Distal DVT (dDVT) is often asymptomatic and data about its incidence and prognosis are scanty, especially in high risk medical inpatients. Therefore, no consensus exists on the value of detecting and treating dDVTs. Aim of study was to evaluate incidence and characteristics of asymptomatic isolated dDVT at admission in an Internal Medicine department.

Materials and methods

Consecutive patients hospitalized for acute medical illnesses, in whom VTE was not the admission diagnosis, underwent Doppler Ultrasonography. For all patients with dDVT standard treatment with therapeutic doses of low molecular weight heparin or fondaparinux was proposed. Follow-up visits were scheduled at 1, 6 and 12 weeks.

Results

One-hundred-fifty-four patients were enrolled. In 4.5% a proximal DVT and in 16.2% an asymptomatic dDVT were found. Female sex, elevated age and renal and electrolyte abnormalities were significantly associated to dDVT (p = 0.014, p = 0.009 and p = 0.046, respectively). Only low degree of mobility (LDM) was independently associated to dDVT [OR 7.97 (95%CI 2.42-26.27), p = 0.001)]. A high mortality rate, not for VTE-related causes, was found, especially in the first week, among dDVT patients.

Conclusions

We found a high incidence of clinically silent dDVTs. LDM evaluation could be useful to select patients at high risk in whom to perform a search for dDVT.     

The impact of co-morbid conditions on family history of venous thromboembolism in Whites and Blacks

Introduction

Our objectives were to compare the magnitude of family history as a risk factor for venous thromboembolism (VTE) risk between Blacks and Whites, and to assess the impact of co-morbid conditions on familial risk for VTE.

Materials and methods

We used data from the Genetic Attributes Thrombosis Epidemiology (GATE) study, a matched case-control study which enrolled Blacks and Whites aged 18-70 years in Atlanta, Georgia. A total of 1,094 case patients with a deep vein thrombosis (DVT) or pulmonary embolism (PE) and 1,264 control patients were interviewed about their family history.

Results

Family history of VTE was a statistically significant risk factor for VTE among Blacks (odds ratio (OR) = 2.9, 95% confidence interval (CI) 2.0-4.1; P value < 0.0001) and among Whites (OR = 2.7, 95% CI 1.9-3.7; P value < 0.0001); among Blacks and Whites who were obese or had hypertension; among Blacks who had diabetes mellitus or cancer; as well as among males and females, and across all age categories. Family history of VTE increased the risk of VTE among Blacks with cancer by about 6-fold, whereas among Blacks without cancer the increased risk due to a positive family history was about 3-fold; a 2-fold relative difference. In addition, family history was a risk factor for VTE among case patients with DVT only or with PE only. The effect of family history generally was stronger among those with recurrent episodes of VTE compared with a first episode of VTE. For example, family history of any VTE was a strong risk factor among Black females with recurrent VTE compared with Black females with first VTE (OR = 3.9, 95% CI 2.0-7.5; P value < 0.0001).

Conclusion

Our study indicated that the adjusted attributable fraction for VTE was 16.9% among Blacks vs. 18.3% among Whites, and certain co-morbid conditions could further increase the risk of VTE associated with a positive family history of VTE.     

Hospital mortality due to pulmonary embolism and an evaluation of the usefulness of preventative interventions

Background

Mortality rates due to pulmonary embolism (PE) are difficult to estimate often due to the presence of comorbid disease.

Objectives

To determine the accuracy of hospital records in identifying PE cases, PE-related mortality, and the number of PE-related deaths which are potentially preventable.

Methods

Retrospective chart review of PE cases hospitalized at The Ottawa Hospital over an 8 year period. Cases were reviewed to determine accuracy of coding, as well as the certainty with which PE was the cause of death. In PE-related deaths, a determination was made as to whether any interventions may have been life-saving.

Results

498 cases of 612 (81%) cases coded as PE were correctly coded. 111 (22%) died during hospitalization, 63% of deaths were attributed to PE. The presence of a cardiorespiratory comorbidity or cancer was independently associated with an increased rate of death due to PE. 54% of PE-related deaths were determined to be potentially preventable, most commonly by appropriate DVT prophylaxis. A significantly higher number of cancer patients as compared to non-cancer patients may have potentially had their death due to PE prevented by an inferior vena cava filter (IVCF). Systemic thrombolysis was deemed to be potentially life-saving in 1/38 PE-related deaths.

Conclusion

Hospital mortality due to clinically recognized PE can be determined by chart review of PE cases identified using the ICD coding system. Death due to PE is often potentially preventable; in the subgroup with cancer and DVT/PE, an IVCF may be a potentially useful intervention to prevent death due to PE. Prospective studies are needed to confirm these results.     

Circulating tissue factor positive microparticles in patients with acute recurrent deep venous thrombosis

Introduction

Circulating tissue factor positive microparticles (MPTF) were reported in a wide range of diseases with thrombotic tendency. Though D-dimer assay had a high negative predictive value for deep venous thrombosis (DVT) recurrence, there are currently no reliable positive predictors for recurrent DVT. We therefore quantified MPTF in patients with acute recurrent DVT to determine whether MPTF levels could be used to predict recurrent DVT.

Materials and Methods

Microparticles (MPs) were isolated from plasma of initial DVT patients (n = 25), recurrent DVT patients (n = 25) and sex- and age-matched healthy individuals (n = 25), stained with annexin V, cell-specific monoclonal antibodies (MoAbs) and a MoAb directed against tissue factor (TF), and analyzed by flow cytometry. We also determined the plasma procoagulant activity with a Human TF Chromogenic Activity Assay Kit.

Results

We found total MPTF to be elevated in recurrent DVT patients versus normal individuals (P = 0.001). The number of monocyte-derived MPTF in both initial and recurrent DVT was higher than in normal individuals (P < 0.01, respectively). The platelet and endothelial cell derived MPTF in recurrent DVT were significantly increased relative to other MPTF (P < 0.05), although there was no difference between initial DVT patients and normal individuals. We demonstrated elevated procoagulant activity of platelet-free plasma in DVT patients relative to normal individuals, and a positive correlation with MPTF.

Conclusions

The elevated MPTF could be a potentially predictor for DVT recurrence. Further studies are needed to validate its sensitivity and specificity.     

Prospective diagnostic accuracy assessment of the HemosIL HS D-dimer to exclude pulmonary embolism in emergency department patients

Introduction

Chest pain and shortness of breath are among the most common symptoms requiring immediate evaluation. Testing for pulmonary embolism (PE) has become easier and widespread due to D-dimer blood tests. Safe use of these tests is only possible if sensitivity is high and they are used in non-high probability patients. We evaluated diagnostic performance of the HemosIL HS D-dimer, which despite FDA approval in 2005, has been minimally reported in prospective standard clinical care.

Materials and methods

We used a prospective observational study design to follow patients in a single center with the HemosIL HS ordered for symptoms of possible PE with positive test result if > 243 ng/ml. The outcome was PE or deep venous thrombosis (DVT) at the time of presentation or subsequent 45 days determined by structured evaluation of imaging tests, phone, or medical record follow-up in all patients.

Results

529 patients received a D-dimer and 4.7% were ultimately diagnosed with PE or DVT. The sensitivity of the HemosIL HS was 96.0% (95% CI; 79.6 to 99.9%) specificity was 65.7% (95% CI; 61.4 to 69.8%) and likelihood ratio negative was 0.06 (95% CI; 0.01 to 0.42). The probability of PE in patients with a negative D-dimer was 1/332 or 0.3% (95% CI; 0.01% to 1.67%). The receiver operator curve had an area under the curve of 0.87 and supported the current cut-point as optimal.

Conclusions

The HemosIL HS D-dimer had high sensitivity, very low negative post-test probability and is useful in excluding PE in the acute care setting.     

The G534E-polymorphism of the gene encoding the Factor VII-activating protease is a risk factor for venous thrombosis and recurrent events

Introduction

A single nucleotide polymorphism of the factor VII activating protease (FSAP), FSAP Marburg I (rs7080536) has been identified as a risk factor for venous thrombosis, but its clinical role has so far been controversial in part due to small cohort sizes. The aim of the present case-control study was to elucidate the impact of the FSAP Marburg I polymorphism (FSAP-MI) on the development of venous thromboembolic disease (VTE) with other known sequence variations, including Factor V Leiden (rs6025) and Factor II G20210A (rs1799963).

Materials and Methods

The study included 891 patients (312 male and 579 female) with a history of deep venous thrombosis (DVT) and/or pulmonary embolism (PE) and 1283 healthy blood donors with no history of venous thromboembolic disease.

Results

We found that besides to the well-established aforementioned sequence variations of FV and Prothrombin, the FSAP Marburg I (FSAP-MI) polymorphism was significantly associated with the development of DVTs (1.65 (1.16-2.34) OR (95% CI)) and recurrent thromboembolic events (DVT and PE) (2.13 (1.35-3.36) OR (95% CI)). Comparing patients displaying one or more events FSAP-MI was still associated with the development of recurrent thromboembolic events (1.64 (1- 2.69) OR (95% CI)).

Conclusions

We conclude that FSAP Marburg-I genotyping may be used to determine the risk for thromboembolic disorders in patients with suspected thrombophilia and known DVT or PE.     

Incidence of asymptomatic coronary thrombosis and plaque disruption: Comparison of non-cardiac and cardiac deaths among autopsy cases

Background

Autopsy studies have revealed a high incidence of thrombus formation in patients who died of acute myocardial infarction (AMI) or sudden coronary death. However, the incidence of thrombus formation and plaque disruption in patients with non-cardiac death (NCD) remains unclear.

Methods

To evaluate the incidence and morphological characteristics of thrombi and plaque disruption in patients with NCD, we examined 102 hearts from NCD autopsy cases and 19 from those who had died of AMI.

Results

We found fresh coronary thrombi in 10 cases with NCD and in 14 with AMI (10% vs. 75%, p < 0.001). Seven and three thrombi were associated with plaque erosion and rupture, respectively among the NCD cases. The incidence of plaque rupture was significantly higher in AMI than in NCD (54% vs. 3%, p < 0.001). The size of coronary thrombi in NCD cases was small and the luminal areas were not significantly affected. Plaques beneath thrombi in NCD had a smaller lipid core and a thicker fibrous cap than those in AMI. Among risk factors for cardiovascular events, hypertension and diabetes mellitus were significantly associated with the incidence of thrombosis in patients with NCD.

Conclusion

Coronary thrombosis is a frequent complication in patients with NCD. These small thrombi might not be associated with the onset of clinical events, but with plaque progression in atherosclerosis.     

Eosinophil count predicts mortality following percutaneous coronary intervention

Introduction

Several inflammatory markers have been shown to be independent predictors for both the development of clinically significant atherosclerosis and for adverse outcome in patients with symptomatic coronary artery disease (CAD). We investigated the prognostic role of eosinophil count in low to intermediate risk patients with CAD.

Methods

We studied 909 patients admitted for elective or urgent percutaneous coronary intervention (PCI) from April 2002 to December 2004, and measured pre-procedural total and differential white blood cell (WBC) counts. Inter-tertile WBC differences in short (6 months) and long term (up to 74 months) mortality were analysed after adjusting for differences in baseline characteristics.

Results

Over a median period of 54 months (inter-quartile range 47-65), a total of 138 deaths (15.2%) occurred, of which 24 were in the first 6 months of follow-up. Cox regression analysis showed that high pre-procedural eosinophil count (top tertile) was associated with improved outcome within the first 6 months (OR = 0.23 [0.06-0.84]; p = 0.03) but after this period there was an increased risk of mortality (OR = 2.21, [1.26-3.88]; p = 0.006).

Conclusions

Eosinophil count is a novel biomarker for risk stratification of CAD patients, which was associated initially with reduced mortality, but after 6 months with increased mortality.     

The incidence of deep vein thrombosis in women undergoing cesarean delivery

Introduction

Venous thromboembolism (VTE) is one of the leading causes of maternal mortality in the United States. Cesarean delivery is a known risk factor. This study was to determine the incidence of deep vein thrombosis (DVT) post cesarean delivery.

Materials and Methods

This was a prospective cohort study where two patients having undergone cesarean delivery each day were randomly selected. A lower extremity compression ultrasound was performed prior to hospital discharge. If no DVT was detected, participants were asked to return for a second ultrasound two weeks postpartum. Participants were also telephone-interviewed at three months for reported VTE.

Results

Of the 194 patients who consented to study participation, only one participant developed DVT after cesarean delivery, giving an overall incidence of 0.5% (95% CI, 0.1 to 2.8%). There were no DVT identified on the second ultrasound nor VTE reported 3 months postpartum.

Conclusions

We found the DVT rate after cesarean delivery to be 0.5%.     

Physical activity in patients with deep venous thrombosis: a systematic review

Objectives

We performed a systematic review to assess the benefits or risks of physical activity in patients with an acute or previous DVT of the leg.

Data sources

PubMed, EMBASE and Science Citation Index were searched without language restrictions up to July 2007. Bibliographies of retrieved articles and personal files were also searched.

Review methods

Randomized trials and prospective cohort studies that included patients with acute or previous DVT, described an exercise intervention or exercise exposure, and described any related clinical outcome were selected. Data were independently extracted by 2 investigators.

Results

Seven randomized trials and two prospective observational studies were included. Early exercise, compared with bed rest, was associated with a similar short-term risk of pulmonary embolism in patients with acute DVT and led to more rapid resolution of limb pain. In patients with acute DVT, a 6 month daily walking program led to similar degrees of vein recanalization and improvement in quality of life as controls. In patients with previous DVT, 30 min of vigorous treadmill exercise did not worsen venous symptoms and improved calf muscle flexibility; a 6 month exercise training program improved calf muscle strength and pump function; and high levels of physical activity at one month tended to be associated with reduced severity of postthrombotic symptoms during the subsequent 3 months.

Conclusions

Early walking exercise is safe in patients with acute DVT and may help to reduce acute symptoms. Exercise training does not increase leg symptoms acutely in patients with a previous DVT and may help to prevent or improve the postthrombotic syndrome.     

Incidence and time course of asymptomatic deep vein thrombosis with fondaparinux in patients undergoing total joint arthroplasty

Introduction

There are many reports concerning fondaparinux prophylaxis of asymptomatic deep vein thrombosis (DVT) after total hip arthroplasty (THA) or total knee arthroplasty (TKA), but little is known about the time course of aymptomatic DVT development during the administration of fondaparinux. The aim of the present study was to define the incidence and time course of aymptomatic DVT development during administration of fondaparinux, and to assess the efficacy of fondaparinux in resolving DVT.

Materials and Methods

We studied consecutive71 patients who underwent THA surgery, and 30 patients who underwent TKA surgery with fondaparinux prophylaxis. Patients received once-daily subcutaneous injections of 2.5 mg of fondaparinux for 14 days after surgery. DVT was diagnosed by ultrasonography, and it was scheduled on the day of surgery on day 1, day 4, and day 14 after surgery.

Results

In patients who received fondaparinux for 14 days after THA surgery, the incidence of DVT was 0% on the day of the surgery, 13.6% at day 1, 27.1% at day 4, and 11.9% at day 14. In patients who received fondaparinux for 14 days after TKA surgery, the incidence of DVT was 4.2% on the day after surgery, 50.0% at day 1, 58.3% at day 4, and 20.8% at day 14. The incidence of DVT after THA or TKA surgery at day 14 was significantly reduced compared to that at day 4.

Conclusion

The incidence of asymptomatic DVT up to day 4 was high, but with 14 days continued treatment of fondaparinux, the incidence of asymptomatic DVT occurring at postoperative day 4 was significantly reduced at day 14.     

Factor VIII contributes to platelet-fibrin thrombus formation via thrombin generation under low shear conditions

Introduction

Thrombus growth under low blood flow velocity plays an important role in the development of deep venous thrombosis (DVT). Increased plasma levels and activities of coagulation factor VIII (FVIII) comprise risk factors for DVT and pulmonary thromboembolism.

Objective

To localize FVIII in human venous thrombi of DVT and to determine whether FVIII contributes to thrombus formation under low shear conditions.

Methods

The localization of FVIII in venous thrombi obtained from patients with DVT was examined by immunohistochemistry. The role of FVIII in thrombus formation was investigated using a flow chamber system. Venous blood from healthy volunteers were incubated with an anti-FVIII monoclonal antibody (VIII-3776) or non-immunized mouse IgG₁. Blood samples were perfused on immobilized type III collagen at wall shear rates of 70/s and 400/s and then the surface area covered by platelets and fibrin was morphometrically evaluated. Prothrombin fragment 1+2 (PF1+2) generation was measured before and after perfusion.

Results

Venous thrombi of DVT comprised a mixture of platelets, fibrin and erythrocytes. Factor VIII appeared to be colocalized with glycoprotein IIb/IIIa, fibrin and von Willebrand factor in the thrombi. VIII-3776 specifically recognized the light chain of FVIII and prolonged the activated partial thromboplastin time (aPTT), but not prothrombin time (PT). The antibody significantly reduced platelets and fibrin covering, as well as PF1+2 generation at wall shear rates of 70/s and 400/s.

Conclusions

These results suggest that FVIII contributes to platelet aggregation and fibrin formation via thrombin generation under low shear conditions.     

Comparison of the clinical usefulness of two quantitative D-Dimer tests in patients with a low clinical probability of pulmonary embolism

Background

Quantitative D-Dimer tests are established methods in the non-invasive diagnostic management to rule out venous thromboembolism (VTE). The diagnostic performance and the clinical efficiency different D-Dimer assays in the exclusion of pulmonary embolism (PE) have not yet been compared in a clinical outcome study.

Objective

Evaluation of the efficiency and safety of excluding the diagnosis of PE with two different quantitative D-Dimer assays in consecutive patients with clinically suspected PE.

Patients and Methods

We studied the VTE-failure rate of 2206 consecutive patients with an unlikely clinical probability in whom VIDAS or Tinaquant D-Dimer tests were performed.

Results

The prevalence of PE in 1238 patients whose D-Dimer level was analyzed with Tinaquant assay was 11%. The VIDAS assay group consisted of 968 patients with a PE prevalence of 13%. The VIDAS assay had a sensitivity of 99.2% (95%CI; 96- > 99.9%), the Tinaquant assay of 97.3% (95%CI; 93 -99%). The negative predictive value (NPV) in the Tinaquant assay group was 99.4% (95%CI 98-99.8%) in comparison to 99.7% (95%CI 99-> 99.9%) in the VIDAS assay group. During 3 month of follow-up, there were no fatal cases of PE among patients with normal D-Dimer and unlikely clinical probability in both D-Dimer assay groups. In addition, the test efficiency of Tinaquant assay was significantly higher in comparison to VIDAS assay (52% vs 42%, p < 0.001).

Conclusion

Both Tinaquant and VIDAS D-Dimer tests perform equally well in combination with an unlikely clinical probability in excluding PE. The Tinaquant test was shown to be more efficient.