High plasma levels of factor VIII and risk of recurrence of venous thromboembolism

Genetic Variants Identified by Whole Exome Sequencing in a Large Italian Family with High Plasma Levels of Factor VIII and Von Willebrand Factor

High plasma levels of factor VIII (FVIII) and von Willebrand factor (VWF) have been indicated as independent risk factors for venous thromboembolism. However, the genetic factors responsible for their increase remain poorly known. In a large Italian family with high FVIII/VWF levels and thrombotic episodes, whole exome sequencing (WES) was performed on 12 family members to identify variants/genes involved in FVIII/VWF increase. Twenty variants spread over a 8300 Kb region on chromosome 5 were identified in 12 genes, including the low frequency rs13158382, located upstream of the MIR143/145 genes, which might affect miR-143/145 transcription or processing. The expression of miR-143/145 and VWF mRNA were evaluated in the peripheral blood mononuclear cells of six family members. Members with the variant (n = 3) showed lower levels of both miRNAs and higher levels of VWF mRNA compared to members without the variant (n = 3). An analysis of genetic and expression data from a larger cohort of individuals from the 1000 Genomes and GEUVADIS project confirmed a statistically significant reduction (p-value = 0.023) in miR-143 in heterozygous (n = 35) compared to homozygous wild-type individuals (n = 386). This family-based study identified a new genetic variant potentially involved in VWF increase by affecting miR-143/145 expression.

Plasma levels of coagulation factors VIII and IX and risk of venous thromboembolism: Systematic review and meta-analysis

INTRODUCTION

The associations of plasma factor VIII (FVIII) and factor IX (FIX) levels with risk of venous thromboembolism (VTE) are not well defined. We performed a systematic review and meta-analysis of these associations.

METHODS

Random effects inverse-variance weighted meta-analysis was used to estimate pooled odds ratios for comparisons across equal quartiles of the distributions and 90 % thresholds (higher versus lower), and for testing linear trends.

RESULTS

Among 15 studies (5327 cases) the pooled odds ratio of VTE for the fourth versus first quarter was 3.92 (95 % confidence interval 1.61, 5.29) for FVIII level; and among 7 studies (3498 cases) 1.57 (1.32, 1.87) for FIX level. Comparing factor levels above, versus below, the 90th percentile, the estimated pooled odds ratios were 3.00 (2.10, 4.30) for FVIII; 1.77 (1.22, 2.56) for FIX; and 4.56 (2.73, 7.63) for both FVIII and FIX considered jointly.

CONCLUSIONS

We confirm increases in risk of VTE across population distributions of FVIII and FIX levels. Levels above the 90th percentile have almost twice the risk for FIX level compared to levels below; three-fold risk for FVIII level; and almost five-fold risk for both FVIII and FIX levels elevated.

Study protocol for assessment of the coagulation potential of concomitantly used factor VIII concentrates in patients with haemophilia A with emicizumab prophylaxis (CAGUYAMA Study): a multicentre open-label non-randomised clinical trial

INTRODUCTION

Emicizumab prophylaxis substantially reduces bleeding episodes in patients with haemophilia A (HA). The haemostatic efficacy of emicizumab in patients with HA is estimated as approximately 15% based on mimic activity of factor (F) VIII. Although it has been proven effective in preventing bleeding, its haemostatic effect during breakthrough bleeding or surgery is considered insufficient. Therefore, haemostatic management of emicizumab-treated patients with HA without inhibitors frequently requires FVIII replacement therapy. In haemostatic management of emicizumab-treated patients with HA, conventional FVIII dosage calculations are used in clinical practice without considering the coagulant effects of emicizumab.

METHODS AND ANALYSIS

In the CAGUYAMA study, 100 patients with HA without inhibitors will be enrolled for a maximum duration of 1 year, and samples of 30 events following the concomitant use of FVIII concentrates (30±5 U/kg) with emicizumab will be collected. An 'event' is defined as obtaining blood samples at preadministration and postadministration of FVIII concentrates during a breakthrough bleeding or a surgical procedure. Global coagulation assays will be used to measure the coagulation potential of the obtained samples. Clot waveform analysis (CWA) is used to identify the primary end-point, that is, the degree of improvement in the maximum coagulation rate at preadministration and post-administration of fixed-dose FVIII concentrations. The parameter obtained from CWA, which is triggered by an optimally diluted mixture of prothrombin time reagent and activated partial thromboplastin time reagent, is reported to be an excellent marker for assessing the degree of improvement of the coagulation potential in emicizumab-treated plasmas.

ETHICS AND DISSEMINATION

The CAGUYAMA study was approved by the Japan-Certified Review Board of Nara Medical University (Approval ID; nara0031). The study results will be communicated through publication in international scientific journals and presentations at (inter)national conferences.

TRIAL REGISTRATION NUMBER

jRCTs051210137.

Role of factor VIII, IX, and XI in venous thrombosis recurrence risk in adults and children: A systematic review

Background

Predicting recurrent venous thromboembolic events (VTEs) is challenging in clinical practice for both adults and children, but it is relevant for clinical management. Identifying laboratory risk factors for VTE recurrence may aid in clinical decision-making.

Objective

The goal of this systematic review is to investigate the predictive role of FVIII, IX, or XI in recurrent VTE in adult and pediatric patients with a first VTE.

Methods

A systematic review of the published literature was conducted in databases MEDLINE In-Process, Other Nonindexed Citations, MEDLINE Epub Ahead of Print, EMBASE Classic + EMBASE (OvidSP), and Cochrane (Wiley). We included observational and interventional studies that comprised adults or children with a first VTE, FVIII, FIX, and/or FXI and objectively confirmed VTE recurrence. The quality in prognosis studies tool was used to assess the risk of bias.

Results

We identified 2177 unique studies, of which 19 were included (18 for adults and 1 for children). The risk of bias was overall low to moderate. The studies were heterogenous with regards to population (provoked/unprovoked primary VTE), exposure (type of assay and cut-off values), and statistical analysis results (measures of association and modeling strategy). In adults, contradictory evidence was found for FVIII and FXI as outcome predictors, while no research could establish if FIX predicts VTE recurrence. Data in pediatrics were limited. Given the extensive heterogeneity of the literature, a meta-analysis was not performed.

Conclusions

Overall, there is contradictory evidence that FVIII, FIX, or FXI predict recurrent VTE in adults and children. Addressing heterogeneity is a relevant aspect to consider in future studies investigating prognostic factors for VTE recurrence.

High levels of factor VIII activity in patients with acquired hemophilia A in remission are associated with unusually low coagulation potentials

BACKGROUND

Elevated factor VIII activity (FVIII:C) is often observed in patients with acquired hemophilia A (PwAHA) in remission. However, comprehensive coagulation potentials in this patient group remain to be investigated.

AIM

To evaluate comprehensive coagulation potentials in PwAHA.

METHODS

We investigated coagulation function in eleven PwAHA with high FVIII:C (> 150 IU/dL) using thrombin generation assay (TGA) and/or rotational thromboelastometry (ROTEM), and compared findings with results obtained from contrived samples generated by spiking recombinant FVIII.

RESULTS

The median FVIII:C and FVIII inhibitor titers during remission in enrolled PwAHA were 206 IU/dL and 0.44 BU/mL, respectively. In all patients, lag time and time to peak were either prolonged or normal compared to contrived samples corresponding to their FVIII:C. However, higher values of peak thrombin and endogenous thrombin potentials compared to contrived samples were observed in two patients. ROTEM parameters were within normal ranges in all cases. One patient (FVIII:C 171 IU/dL) developed venous thrombosis and pulmonary embolism, but TGA parameters showed low or normal coagulation potential compared to contrived samples corresponding to his FVIII:C.

CONCLUSION

PwAHA with high FVIII:C could exhibit lower coagulation potentials than those corresponding to their FVIII:C.

Incidence and factors predictive of recurrent thrombosis in people with non-cirrhotic portal vein thrombosis

BACKGROUND & AIMS

Clinical guidelines do not recommend long-term anticoagulation in non-cirrhotic splanchnic vein thrombosis (NC-SVT) without underlying thrombophilia because it is assumed that there is a very low risk of recurrent thrombosis (RT). Our first aim was to describe the incidence of RT in people with NC-SVT without an indication for long-term anticoagulation. The second aim was to identify RT risk factors and afterwards verify them in a validation cohort.

METHODS

This is a multicentre, retrospective observational study evaluating risk factors for RT in 64 people with NC-SVT of idiopathic/local factor aetiology. In a subgroup of 48 individuals, the potential value of additional thrombophilic parameters to predict RT was analysed. Findings were validated in 70 individuals with idiopathic/local factor NC-SVT.

RESULTS

Of the 64 participants in the training cohort, 17 (26%) presented splanchnic and/or extrasplanchnic RT (overall-RT) during follow-up (cumulative incidence: 2, 10, 19, and 34% at 1, 2, 5, and 10 years, respectively). In addition, 53% of people with splanchnic RT were asymptomatic. No clinical or biochemical parameters predicted overall-RT. However, in the 48 people with an additional comprehensive thrombophilic study, factor VIII ≥150% was the only independent factor predicting overall-RT (hazard ratio 7.10, 95% CI 2.17-23.17, p <0.01). In the validation cohort, 19 individuals (27%) presented overall-RT, and it was also independently predicted by factor VIII >150% (hazard ratio 3.71, 95% CI 1.31-10.5, p <0.01). The predictive value of factor VIII was confirmed in both people with idiopathic/local factor aetiology associated NC-SVT.

CONCLUSIONS

People with idiopathic/local factor NC-SVT are at risk of overall-RT. Splanchnic RT can be asymptomatic and requires screening for its detection. Values of factor VIII ≥150% may help identify individuals at high risk of overall-RT who could benefit from long-term anticoagulation.

IMPACT AND IMPLICATIONS

People with idiopathic/isolated local factor non-cirrhotic portal vein thrombosis were previously thought to be at minimal risk of re-thrombosis and therefore did not receive scheduled follow-up. The results of this study are of special interest for hepatologists treating people with non-cirrhotic splanchnic thrombosis, as they show a 25% incidence of re-thrombosis and support the close follow-up of people with factor VIII >150% to ensure the early identification of new thrombotic events.

Current Knowledge on Factor V Leiden Mutation as a Risk Factor for Recurrent Venous Thromboembolism: A Systematic Review and Meta-Analysis

Background

Thrombophilia screening is widely done in clinical practice, and it is claimed that the extent of venous thromboembolism (VTE) recurrence risk in patients with common defects is still not fully understood.

Aim

We aimed to summarize data of all observational studies prospectively assessing the association of heterozygous factor V Leiden (FVL) mutation and recurrent VTE in patients with VTE, and to calculate pooled relative risks (RR), overall and in various subgroups.

Methods

We searched MEDLINE and EMBASE databases for cohort studies prospectively assessing VTE recurrence in patients with and without FVL mutation (PROSPERO: CRD42021182800). Data were extracted on cohort and study-level. The methodological quality was assessed using the Newcastle-Ottawa Scale (NOS). RR were calculated overall and in subgroups using a random-effects model.

Results

From 31 cohorts, 24 studies were finally included summarizing 13,571 patients. Heterozygous FVL mutation was identified in 2,840 individuals (21%). The methodological quality was estimated to be high in 20 studies (83%). The overall RR was 1.46 (95% CI: 1.31, 1.64), consistent across subgroups.

Conclusions

Pooling all high-quality epidemiological data, the risk of recurrent VTE was increased by 46% in patients with heterozygous FVL mutation. Against the background of established risk factors, the FVL mutation plays only a marginal role in the risk assessment for recurrent VTE.

Reference values of coagulation assays performed for thrombophilia screening after a first venous thrombosis and their intra-patient associations

INTRODUCTION

No reference values are currently available for coagulation assays performed for thrombophilia screening prescribed according to guidelines, after a first venous thromboembolic (VTE) event, and we have no idea of the intra-patient associations between results.

METHODS

We performed a retrospective study of consecutive prescriptions fulfilling guidelines in a French university hospital from 2010 to 2019 (n = 3842) from the Glims® laboratory information system. We collected results of 12 parameters: aPTT, PT, fibrinogen (Fg), one-stage clotting methods for factors VIII, IX, XI and II (FVIII, FIX, FXI, FII), antithrombin (using an amidolytic assay: AT), protein C and S (using clotting assays: PC and PS) and mixing tests of a lupus-anticoagulant sensitive aPTT and of DRVVT.

RESULTS

We show the results of the 12 parameters from 3603 individual files with less than 6 missing values, then describe these distributions and correlations between results from 2930 files with no missing value. We give the frequency of results described as indicating a risk of first VTE or of VTE recurrence. We propose 2 quantitative scores linking the 12 parameters at the individual level and reflecting their degree of dispersion with respect to their mean, describe the values of these scores and their associations with thrombophilic results.

CONCLUSIONS

These normal values should help laboratory workers to validate process results and to assess their degree of originality. Our 2 scores should help to determine the intra-patient plausibility of associations of results. The usefulness of these laboratory scores for predicting clinically-relevant outcomes deserves to be investigated.

Correlation between serum factor VIII:C levels and deep vein thrombosis following gynecological surgery

Deep vein thrombosis (DVT) is common in patients following gynecological surgery. Coagulation factor VIII (FVIII) is an important part of the human coagulation system, and FVIII:C is a component of FVIII with anticoagulant activity. 800 patients who underwent gynecological surgery were enrolled. General clinical data were harvested, and pre – and postoperative serum FVIII levels were determined. Lower-extremity ultrasound examination and/or postoperative pulmonary angiography were performed. Related data were analyzed statistically. DVT was the first manifestation of venous thromboembolism in all cases. There were a total of 46 cases, and the incidence of DVT was 5.8%. Progression to pulmonary embolism was confirmed in 16 cases, with an incidence of 2.0%. The independent risk factors for DVT after gynecological surgery were postoperative FVIII:C levels (odds ratio [OR] = 1.01), age (OR = 6.57), and operation time ≥3 hours (OR = 2.90) (P < 0.05). When the FVIII:C level was greater than the 75th centile (≥150 IU/dL), the risk of DVT was 2.99 times higher than that below the 25th centile (<100 IU/dL) (P < 0.05). When combined with the risk factor of operation time ≥3 hours, the risk increased to 3.17 times (P = 0.10). When combined with age ≥60 years, the risk was significantly increased, reaching 12.0 times (P < 0.05). Serum FVIII:C levels are an independent risk factor for DVT after gynecological surgery. Higher levels increase the risk of DVT after gynecological surgery, and they may have a dose-dependent relationship. A synergistic effect exists in combination with other risk factors, which further increases the risk.

Predicting Recurrent Venous Thromboembolism in Patients With Deep-Vein Thrombosis: Development and Internal Validation of a Potential New Prediction Model (Continu-8)

Background: Previous prediction models for recurrent thromboembolism (VTE) are often complicated to apply and have not been implemented widely.

Aim: To develop and internally validate a potential new prediction model for recurrent VTE that can be used without stopping anticoagulant treatment for D-dimer measurements in patients with provoked and unprovoked DVT.

Methods: Cohort data of 479 patients treated in a clinical care pathway at Maastricht University Medical Center were used. Predictors for the Cox proportional hazards model (unprovoked DVT, male gender, factor VIII levels) were derived from literature and using forward selection procedure. The scoring rule was internally validated using bootstrapping techniques and the predictive ability was compared to existing prediction models.

Results: Patients were followed for a median of 3.12 years after stopping anticoagulation treatment (IQR 0.78, 3.90). Sixty-four of 479 patients developed recurrent VTE (13%). The scoring rule consisted of unprovoked DVT (yes: 2 points), male sex (yes: 1 point), and factor VIII > 213 % (yes: 2 points) and was categorized into three groups [i.e., low risk (score 0), medium risk (scores 1, 2, or 3) and high risk (scores 4 and 5)]. The concordance statistic was 0.68 (95% CI: 0.61, 0.75).

Conclusion: The discriminative ability of the new Continu-8 score was adequate. Future studies shall verify this score in an independent setting without stopping anticoagulation treatment.

Elevated plasma factor VIII levels in a mixed patient population on anticoagulation and past venous thrombosis

BACKGROUND

Thrombophilia conditions are associated with an increased risk of venous thromboembolism. Elevated plasma levels of factor VIII (>150 IU/dL) increase the risk of venous thrombosis. The aim of this report is to analyze a subset of patients in whom plasma factor VIII levels were investigated as part of a thrombophilia panel at a specialty venous clinic at a tertiary care hospital.

METHODS

From January 2019 to December 2019, records of all patients (n = 306) who had a plasma factor VIII level assay performed as part of a thrombophilia panel were retrospectively analyzed. Group 1 (n = 92) had normal factor VIII levels (≤150 IU/dL), whereas group 2 (n = 214) had elevated factor VIII levels (>150 IU/dL). Venous thromboembolic events were classified as provoked if there was an association with surgery, trauma, immobilization, orthopedic fracture, peripartum period, or use of hormones. If there was no associated factor identifiable in the patient's history, the event was considered unprovoked.

RESULTS

The median age for patients in groups 1 and 2 was 55 and 65 years, respectively. Family history of deep venous thrombosis (DVT) was noted in 6 patients in group 1 (6.5%) vs 77 patients in group 2 (36%), P value: .0001. Unprovoked DVT was more commonly noted in group 2 patients (66%) compared with group 1 patients (5%), P value: .0001. In addition, venous ulceration was more commonly encountered in group 2 (23%) than group 1 (11%), P value: .008. Factor VIII level >150 IU/dL was a significant predictor of DVT occurrence itself (odds ratio: 3.3, P value <.005). Factor VIII level >200 IU/dL was a significant predictor of occurrence of two or more episodes of DVT (odds ratio: 12.3, P value < .005).

CONCLUSIONS

Factor VIII levels were found to be elevated in a significant proportion of patients in whom thrombophilia testing was performed at a specialty venous clinic. This elevation was more common in patients with venous ulceration, a positive family history of DVT, and a personal history of an unprovoked DVT. Levels above 200 IU/dL were associated with DVT recurrence. This has important implications for secondary prophylactic strategies for DVT.

Predicting the Risk of Recurrent Venous Thromboembolism: Current Challenges and Future Opportunities

Acute venous thromboembolism (VTE) is a commonly diagnosed condition and requires treatment with anticoagulation to reduce the risk of embolisation as well as recurrent venous thrombotic events. In many cases, cessation of anticoagulation is associated with an unacceptably high risk of recurrent VTE, precipitating the use of indefinite anticoagulation. In contrast, however, continuing anticoagulation is associated with increased major bleeding events. As a consequence, it is essential to accurately predict the subgroup of patients who have the highest probability of experiencing recurrent VTE, so that treatment can be appropriately tailored to each individual. To this end, the development of clinical prediction models has aided in calculating the risk of recurrent thrombotic events; however, there are several limitations with regards to routine use for all patients with acute VTE. More recently, focus has shifted towards the utility of novel biomarkers in the understanding of disease pathogenesis as well as their application in predicting recurrent VTE. Below, we review the current strategies used to predict the development of recurrent VTE, with emphasis on the application of several promising novel biomarkers in this field.

Predicting VTE in Cancer Patients: Candidate Biomarkers and Risk Assessment Models

Risk prediction of chemotherapy-associated venous thromboembolism (VTE) is a compelling challenge in contemporary oncology, as VTE may result in treatment delays, impaired quality of life, and increased mortality. Current guidelines do not recommend thromboprophylaxis for primary prevention, but assessment of the patient's individual risk of VTE prior to chemotherapy is generally advocated. In recent years, efforts have been devoted to building accurate predictive tools for VTE risk assessment in cancer patients. This review focuses on candidate biomarkers and prediction models currently under investigation, considering their advantages and disadvantages, and discussing their diagnostic performance and potential pitfalls.

Pathophysiology 1. Mechanisms of Thrombosis in Cancer Patients

Thrombosis is a major cause of morbidity and mortality in cancer patients. The pathogenesis of blood coagulation activation in oncological patients is complex and involves both clinical and biological factors. Abnormalities in one or more coagulation test are common in cancer patients, even without thrombotic manifestations, indicating an ongoing hypercoagulable condition. Moreover, venous thromboembolism (VTE) can be the first symptom of an occult malignancy in an otherwise healthy individual. The levels of laboratory markers of activation of blood coagulation parallel the development of malignancy, being the coagulant mechanisms important for both thrombogenesis and tumor progression. Besides general clinical risk factors for VTE, also disease-specific clinical factors, i.e., type and stage of the tumor, and anticancer therapies increase the thrombotic risk in these patients. Furthermore, biological factors, including the cancer cell-specific prothrombotic properties together with the host cell inflammatory response to the tumor, are relevant as well as unique players in the pathogenesis of the cancer-associated hypercoagulability. Cancer cells produce and release procoagulant and fibrinolytic proteins, inflammatory cytokines, and procoagulant microparticles. They also express adhesion molecules binding to the receptors of host vascular cells (i.e., endothelial cells, platelets, and leukocytes), thereby stimulating the prothrombotic properties of these normal cells, including the shed of cell-specific microparticles and neutrophil extracellular traps. Of interest, several genes responsible for the cellular neoplastic transformation drive the programs of hemostatic properties expressed by cancer tissues. A better understanding of such mechanisms will help the development of novel strategies to prevent and treat the Trousseau's syndrome (i.e., cancer-associated thrombosis).

Measurement of coagulation factors during rivaroxaban and apixaban treatment: Results from two crossover trials

BACKGROUND

Prediction models for venous thromboembolism recurrence will likely be improved by adding levels of coagulation factors. Risk assessment is ideally performed during anticoagulant treatment, however, the influence of direct oral anticoagulants on coagulation factors is uncertain.

OBJECTIVE

To assess the influence of rivaroxaban and apixaban on several coagulation factor levels.

METHODS

In two crossover trials we assessed the influence of rivaroxaban and apixaban intake on factor (F)VIII, FXI and FXII-activity and fibrinogen, von Willebrand factor (VWF:Ag), and d-dimer levels. At three sessions with a washout period in between, blood was taken from 12 healthy male individuals immediately before intake of rivaroxaban 15 mg twice daily (n = 6) or apixaban 10 mg twice daily (n = 6) and three hours after the last intake.

RESULTS

Overall, measured levels were lower after rivaroxaban/apixaban intake. The paired mean difference after rivaroxaban intake was -38 IU/dL (95% CI -43; -33) for FVIII:C, -29 U/dL (95% CI -45; -12) for FXI:C, -22 IU/dL (95% CI -43; -1) for FXII:C, -0.11 g/L (95% CI -0.25; 0.03) for fibrinogen, -7 IU/dL (95% CI -18; 3) for VWF:Ag, -27 ng/mL (95% CI -50; -4) for d-dimer and -0.36 (95% CI -0.57; -0.15) for Ln d-dimer. After apixaban intake this was -29 IU/dL (95% CI -38; -21) for FVIII:C, -29 IU/dL (95% CI -36; -22) for FXI:C, -19 IU/dL (95% CI -24; -15) for FXII:C, -0.18 g/L (95% CI -0.33; 0.03) for fibrinogen, -52 ng/mL (95% CI -100; -4) for d-dimer, 0.25 (-0.60; 0.09) for Ln d-dimer and 1 IU/dL (95% CI -7; 9) for VWF:Ag.

CONCLUSION

FVIII:C, FXI:C, FXII:C, and d-dimer measurements were influenced by rivaroxaban/apixaban intake, while fibrinogen and VWF:Ag were not.

Predicting the risk of recurrent venous thromboembolism

Venous thromboembolism (VTE) is a disease, which often recurs. The recurrence risk is highest in patients with unprovoked proximal deep-vein thrombosis (VT) or pulmonary embolism. Men have a higher risk than women. The risk is low in patients with VTE related to a temporary risk factor such as surgery or estrogen use. Other risk factors include overweight, post-thrombotic syndrome, history of VTE, residual VT or a vena cava filter.

Both factor V Leiden and the prothrombin mutation confer a negligible increase in recurrence risk. High clotting factor levels, deficiency of a natural coagulation inhibitor, or hyperhomocysteinaemia are also associated with an increased risk. Reasons why routine laboratory thrombophilia screening however is no longer warranted are addressed in this article. Prediction rules combining clinical characteristics and coagulation assays have recently been developed. One such model, the Vienna Prediction Model, allows predicting recurrent VTE on the basis of VTE location, sex and D-dimer. This article describes strategies to distinguish between patients with high risk of recurrent VTE from those with a lower risk, who might not benefit from long-term antithrombotic therapy.

Purification and characterization of a new highly pure, double virus inactivated von Willebrand factor concentrate

: Desmopressin-unresponsive von Willebrand disease patients are treated with substitutive therapy, with both pure von Willebrand factor (vWF) and factor VIII/vWF concentrates. We developed a new purification process, easily scalable to industrial level, to obtain a double virus inactivated highly pure vWF. VWF was purified starting from a waste fraction of already in use human plasma-derived factor VIII manufacturing procedure, using only one anionic-exchange chromatographic step. After chromatography, the product was dialyzed, lyophilized, and heat treated. The process resulted in a very highly purified vWF, with a mean specific activity of 95.3 IU of vWF:ristocetin cofactor assay/mg of total proteins. The obtained vWF had a whole structure, as showed by the triplet bands analysis. The residual content of contaminating proteins such as immonoglobulin M and factor VIII was very low. Immunoglobulin A, immunoglobulin G, and fibronectin were totally absent. Notably, the lyophilized highly pure vWF was stable, without the addition of stabilizing proteinaceous material. A new simple purification method was performed, starting from a waste fraction of in use plasma-derived factor VIII process, using one single chromatographic step to obtain a highly pure and double virus inactivated vWF.

Optimal long-term pharmacological treatment of patients with venous thromboembolism that was unprovoked or associated with weak risk factors

INTRODUCTION

Unprovoked venous thromboembolism (VTE) tend to recur. Many factors, patient- or event-related, influence the individual risk of recurrence. After initial and long-term (usually for 3-6 months) anticoagulant therapy, extended anticoagulation has been recommended in patients at high risk of recurrence, provided they do not have a high risk of bleeding. Areas covered: The effect of different risk factors on the risk of recurrence is discussed, as well as risk factors for bleeding. The estimation of individual balance between these two risks is crucial to decide which can be the best treatment duration in single patients. The use of direct oral anticoagulants, with likely less risk of bleeding, may influence the balance. D-dimer assessment during and after anticoagulation is stopped is also commented for its role to help identifying the individual risk of recurrence. Expert commentary: All patients with a first VTE should be reconsidered after the initial 3-6 months of treatment. Anticoagulation can then be stopped or continued in relation to low or very high risk of recurrence, respectively. Serial D-dimer assessment during the first 2 or 3 months after anticoagulation is stopped is useful in patients with uncertain risk evaluation (especially after unprovoked events).

Idiopathic Intracranial Hypertension: Associations with Thrombophilia and Hypofibrinolysis in Men

The existence of an association between idiopathic intracranial hypertension (IIH) and coagulation disorders in men was assessed prospectively. Microthrombi, associated with thrombophilia-hypofibrinolysis, occlude arachnoid sinus villi, thus reducing resorption of cerebrospinal fluid, leading to IIH. Ten consecutively referred men with IIH, nine whites, one African American, median age 36 years, were 2 to 1 matched by age and race by healthy male controls. Polymerase chain reaction assays were done for four thrombophilic and one hypofibrinolytic gene mutations: G1691A factor V Leiden, G20210A prothrombin, C677T MTHFR, platelet glycoprotein IIb/IIIa (PL A1/A2), and 4G/5G polymorphism of the plasminogen activator inhibitor (PAI-1) gene promoter. Coagulation measures in plasma included dilute Russel’s viper venom time (dRVVT), activated partial thromboplastin time (aPTT), the lupus anticoagulant, factor VIII, factor XI, plasminogen activator inhibitor activity (PAI-Fx), protein C antigenic, protein S total (antigenic), protein S free (antigenic), antithrombin III (functional), and resistance to activated protein C (RAPC). Tests performed on serum included anticardiolipin antibodies, homocysteine, and Lp(a). The body mass index was 40 kg/m2 or greater (extremely obese) in two men, 30 to 40 kg/m2(obese) in three, and was 25 to 30 kg/m2 in five (overweight). Cases differed from controls for inherited 4G4G homozygosity of the PAI-1 gene, four of 10 (40%) vs. one of 20 (5%), Fisher’s p [pf]= .031, and for high levels (>21.1 U/mL) of the hypofibrinolytic PAI-1 gene product, PAI-Fx, 5 of 10 (50%) vs. one of 18 (6%), pf = .013. Thrombophilic factor VIII was high (≥ 150%) in three of 10 (30%) cases vs. zero of 16 (0%) controls, pf=. 046. The thrombophilic lupus anticoagulant was present in two of 10 (20%) cases vs. zero of 32 (0%) controls, pf = .052. Heritable hypofibrinolysis and heritable and acquired thrombophilia appear, speculatively, to be treatable etiologies of IIH in men. Understanding contributions of hypofibrinolysis and thrombophilia to the development of IIH should facilitate development of novel new approaches to treat this often-disabling neurologic disorder.

Association between micro particle-tissue factor activity, factor VIII activity and recurrent VTE in patients with acute pulmonary embolism

Studies on the association between microparticle expressing tissue factor (MP-TF) activity, FVIII activity (FVIII:C) and recurrent VTE yielded inconclusive results. We studied these associations in patients diagnosed with acute pulmonary embolism. Plasma levels of MP-TF and FVIII activity were measured in 277 patients with a first and 72 patients with a recurrent VTE. All patients were categorized based on the quintiles of MP-TF and FVIII activity in those with a single VTE. For both markers, odds ratios (ORs) for recurrent VTE were computed using patients in the lowest quintile as a reference group. No association was observed between MP-TF activity and recurrent VTE, with an OR of 1.4 (95 % CI 0.7–2.9) in the highest quintile of MP-TF activity. Compared with the reference group, patients in the highest quintile of FVIII:C were at increased risk of recurrent VTE, OR 4.2 (95 % CI 1.4–12.2). MP-TF activity was not associated with recurrent VTE whereas high FVIII:C levels were associated with a 4-fold increased risk of VTE recurrence. Future prospective studies are necessary to explore the potential of FVIII:C as a tool for risk stratification, either by itself or in combination with other pro-thrombotic markers.

Measurement of factor XIII (FXIII) activity by an automatic ammonia release assay using iodoacetamide blank-procedure: no more overestimation in the low activity range and better detection of severe FXIII deficiencies

Background:

Laboratory investigation with specific factor XIII (FXIII) assays plays a crucial role in diagnosis of FXIII deficiency. According to the International Society on Thrombosis and Hemostasis (ISTH), it is necessary a blank sample with iodoacetamide, provided by the kit or locally prepared, when the ammonia release assays are used, to avoid FXIII activity overestimation.

Methods:

In this study we set up a modification of the Berichrom FXIII chromogenic assay, in which iodoacetamide was added by the BCS analyzer in the reaction mixture of the blank sample, without modifications of the original reagents. We analyzed 100 plasma samples of outpatients with clinical symptoms suggestive of a bleeding diathesis (20 samples had FXIII activity <20%).

Results:

In all samples blank subtraction significantly reduced FXIII activity, mostly in the low activity range group (from 10.1% to 2.4%, p<0.0001). In this group correction with iodoacetamide also increased the agreement with the immunoassay and allowed FXIII activity measure up to 0%.

Conclusions:

Despite the low number of samples included in the study, the described automatic procedure seemed to decrease FXIII activity overestimation and, especially for low activity range samples (<20%), to improve the agreement between FXIII activity and concentration. Our data suggested that iodoacetamide correction could allow the detection of severe FXIII deficiencies (activity <5%) otherwise undiagnosed using the original method.

High coagulation factor VIII and von Willebrand factor in patients with lymphoma and leukemia

The risk of venous thromboembolism is increased in patients with lymphoma and leukemia; however, little is known about the potential underlying hereditary or acquired thrombophilia. We prospectively analyzed procoagulant markers and gene mutations in patients with lymphoma (n = 35) and leukemia (n = 10) at diagnosis and over the course of treatment. Global coagulation tests were normal in all patients, as were antithrombin and protein S. Activated protein C resistance caused by the factor V Leiden mutation was found in four patients, one patient had the G20210A mutation of the prothrombin gene, and one patient had protein C deficiency. The most striking findings were sustained very high levels of factor VIII (>150 %) in 30 patients (68 %), which correlated with high von Willebrand factor. An acute phase response in these patients was ruled out by absence of fever and normal IL-6 and -α. Elevated factor VIII is an independent thrombophilic risk factor and may play an etiologic role in thromboembolic complications in patients with malignant lymphoma. Since high von Willebrand factor is most likely caused by endothelial cell injury, an additional, unknown pathophysiological association with malignant lymphoma and acute leukemia is possible.

Predictive value of factor VIII levels for recurrent venous thrombosis: results from the MEGA follow-up study

BACKGROUND

Prediction of recurrent venous thrombosis remains a challenge in the clinic.

OBJECTIVE

To investigate the predictive value of coagulation factor VIII (FVIII) levels for recurrent venous thrombosis.

PATIENTS/METHODS

Patients, aged 18-70 years with a first venous thrombosis, were followed from discontinuation of anticoagulant treatment (1999-2010 MEGA follow-up study). The levels of FVIII activity, FVIII antigen and von Willebrand factor (VWF) antigen were measured at least 3 months after cessation of anticoagulant treatment.

RESULTS

Of 2242 patients followed for a median of 6.9 years, 343 developed recurrent thrombosis (incidence rate 2.7/100 patient-years; 95% confidence interval [CI] 2.5-3.1). Recurrence rates steadily increased with higher FVIII activity levels, from 1.4 (95% CI 1.0-1.9), 2.3 (95% CI 1.8-2.9), 3.0 (95% CI 2.4-3.7), 3.2 (95% CI 2.5-4.1), 3.9 (95% CI 2.8-5.3) to 5.1 (95% CI 3.8-6.8) per 100 patient-years, for levels ranging from < 100 IU dL(-1) to > 200 IU dL(-1) . Patients in the highest category of FVIII (> 200 IU dL(-1) ) had a three-fold higher recurrence rate than patients in the lowest category (≤ 100 IU dL(-1) ) (hazard ratio 3.4; 95% CI 2.2-5.3). Results were similar for FVIII antigen and VWF antigen levels, in several sensitivity analyses, and FVIII predicted recurrence rates over a long time period. Within subgroups of patients currently assumed to have low recurrence risks, a high level of FVIII was still predictive for recurrences. Adding FVIII to an existing prediction model (DASH score) improved its predictive value, and, after replacement of D-dimer with FVIII, the model performed equally well, if not better.

CONCLUSIONS

FVIII predicted recurrence in a dose-response fashion, overall and in several subgroups, and is a strong candidate component of recurrence prediction tools.

Coagulation factor VIII, IX and XI levels in north Indian patients with venous thromboembolism: first study from India

Studies have shown elevated levels of certain coagulation factors as risk factors for venous thromboembolism (VTE). In this study, we investigated the levels of coagulation factor VIII (FVIII), FIX and FXI in north Indian patients with VTE. A total of 123 patients with VTE were screened prospectively for FVIII, FIX and FXI levels and the conventional risk factors - deficiencies of protein C, S and antithrombin, positivity for antiphospholipid antibodies and the factor V Leiden mutation. Age-matched and sex-matched controls were included. VTE was secondary to known circumstantial and thrombophilic risk factors in 66 (53.7%) patients. In 46.3% (idiopathic VTE) patients, no cause was identified. The mean FVIII levels in idiopathic (187 IU/dl) and secondary VTE patients (185.4 IU/dl) were significantly higher compared with controls (129.6 IU/dl; P < 0.001). However, there was no statistically significant difference in the levels of FIX and FXI between patients and controls (P = 0.214 and 0.198, respectively). Patients with elevated FVIII levels had increased risk of VTE compared with controls (odds ratio: 9.4, 95% confidence interval: 4.7-18.79). On logistic regression analysis after adjusting for surgery and presence of antiphospholipid antibodies, this risk remained unchanged (odds ratio: 9.54, 95% confidence interval: 4.68-19.44). A dose-response relationship was observed with progressive increase in FVIII levels. Elevated FVIII levels constitute an independent risk factor for VTE in the north Indian population. Elevated levels of FIX and FXI were not associated with increased risk of VTE.

Predictors of venous thromboembolism recurrence, adjusted for treatments and interim exposures: a population-based case-cohort study

BACKGROUND

Predictors of venous thromboembolism (VTE) recurrence are uncertain.

OBJECTIVE

To identify predictors of VTE recurrence, adjusted for treatments and interim exposures.

MATERIALS AND METHODS

Using Rochester Epidemiology Project resources, all Olmsted County, MN residents with objectively-diagnosed incident VTE over the 13-year period, 1988-2000, who survived ≥1day were followed for first objectively-diagnosed VTE recurrence. For all patients with recurrence, and a random sample of all surviving incident VTE patients (n=415), we collected demographic and baseline characteristics, treatments and interim exposures. In a case-cohort study design, demographic, baseline, treatment and interim exposure characteristics were tested as potential predictors of VTE recurrence using time-dependent Cox proportional hazards modeling.

RESULTS

Among 1262 incident VTE patients, 306 developed recurrence over 6,440 person-years. Five-year recurrence rates, overall and for cancer-associated, idiopathic and non-cancer secondary VTE, were 24.5%, 43.4%, 27.3% and 18.1%, respectively. In multivariable analysis, interim hospitalization, active cancer, pregnancy, central venous catheter and respiratory infection were associated with increased hazards of recurrence, and warfarin and aspirin were associated with reduced hazards. Adjusting for treatments and these interim risk factors, male sex, baseline active cancer and failure to achieve a therapeutic aPTT in the first 24hours were independently associated with increased hazards of VTE recurrence over the entire follow-up period, while the hazards of recurrence for patient age, chronic lung disease, leg paresis, prior superficial vein thrombosis and idiopathic VTE varied over the follow-up period.

CONCLUSIONS

Baseline and interim exposures can stratify VTE recurrence risk and may be useful for directing secondary prophylaxis.

Long-term increased factor VIII levels are associated to interleukin-6 levels but not to post-thrombotic syndrome in patients with deep venous thrombosis

INTRODUCTION

Increased FVIII levels are a well established risk factor for deep venous thrombosis (DVT), whose etiopathogenesis is not yet well understood. In this study, we aimed to evaluate the possibility that inflammatory markers and post-thrombotic syndrome (PTS) could contribute to FVIII levels in patients with a history of DVT.

DESIGN AND METHODS

It is a case-control study that included 68 patients with DVT of the lower limbs 32 months after the acute episode, and 67 healthy adults as controls. We evaluated plasma levels of FVIII, VWF, D-dimer and serum levels of CRP, IL-6, IL-8, TNF-α in patients and controls. The presence of PTS was evaluated by the Villalta scale.

RESULTS

Patients with DVT presented higher levels of FVIII, VWF and D-dimer when compared to controls (P ≤ 0.001). Almost 50% of patients presented FVIII levels above 90th percentile. Furthermore, IL-6 (1.19 vs. 0.98 pg/mL, P = 0.01) and TNF-α (2.27 vs. 1.57 pg/mL, P ≤ 0.001) were also higher in patients when compared to controls. In a linear regression multivariate model, VWF and IL-6 levels were independent factors associated with FVIII levels (P ≤ 0.001). FVIII levels were not increased in patients with PTS. Patients with PTS showed higher levels of IL-8 when compared to patients without PTS (23.03 vs. 18.20 pg/mL, P = 0.04).

CONCLUSIONS

In conclusion, we demonstrated that DVT is associated with increased levels of inflammatory and coagulation markers, including FVIII, even a long time after the acute episode. Moreover, IL-6 levels were an independent factor associated with FVIII levels. Finally, PTS seems to be related to inflammatory cytokine IL-8, a proinflammatory and proangiogenic chemokine, but not to FVIII levels.

Thrombin generation in Cushing's Syndrome: do the conventional clotting indices tell the whole truth?

Cushing's Syndrome (CS) is associated with an increased mortality, where hypercoagulability seems to have a crucial role in both arterial and venous thrombosis. Parameters of in vitro thrombin generation (TG) such as lag time, peak thrombin and endogenous thrombin potential (ETP), that describe the time until thrombin burst, the peak amount of TG and the total amount of thrombin generated, respectively as well as classical clotting markers were evaluated in 33 CS patients compared to both a group of 28 patients matched for the features of Metabolic Syndrome (MetS) and 31 healthy individuals. CS and MetS patients had shorter lag time (p < 0.0001), higher peak and ETP (p < 0.0001) than healthy controls, though lag time was less shortened in CS (p < 0.0001) respect to MetS group. Prothrombin time (PT) was increased (p < 0.0001) in both CS and MetS patients, while partial thromboplastin time (PTT) was shorter (p < 0.0001) in CS compared to both MetS and healthy group (p < 0.0001). Factor VIII (FVIII), Antithrombin (AT), protein C and S were increased only in CS patients (p < 0.0001). lag time, AT and FVIII correlated to night salivary cortisol (r = + 0.59; p = 0.0005, r = + 0.40; p = 0.003, r = + 0.40; p = 0.04, respectively); PTT correlated inversely to urinary free cortisol (r = -0.45; p = 0.009). BMI correlated negatively to lag time (r = -0.40; p = 0.0001) and positively to peak and ETP (r = + 0.34; p = 0.001, r = + 0.28; p = 0.008, respectively). Obese and diabetic patients had shorter lag time (p = 0.0005; p = 0.0002, respectively), higher ETP (p = 0.0006; p = 0.007, respectively) and peak (p = 0.0003; p = 0.0005, respectively) as well as a more prolonged PT (p = 0.04; p = 0.009, respectively). Hypertensive individuals had higher ETP (p = 0.004), peak (p = 0.0008) and FVIII (p = 0.001). Our findings confirm a prothrombotic state in both CS and MetS patients, though lag time was less shortened in CS. The high levels of endogenous physiological anticoagulants, could possibly represent a protective mechanism against hypercoagulability seen in CS patients.

Venous thrombosis: understanding the paradoxes of recurrence

The decision to continue anticoagulant treatment in patients with a first venous thrombosis after the initial treatment period has strong, life-long implications. Both the risk of recurrence when treatment is stopped and the risk of bleeding when it is continued are high and will persist over a patient's lifetime. For clinicians, rational strategies to stratify their patients into levels of risk of recurrence are limited. To support in the decision to continue or not, it is of the utmost importance to understand why some people develop a second event and others do not and how these people can be identified. This is not easy as, contrary to intuition, the risk profile of a recurrent event is entirely different from that of a first: Some genetic factors that have a major effect on first thrombosis only marginally predict recurrence, while, for instance, the opposite is true for male sex. These paradoxes can be explained when we understand etiology of a first event, how rates for first and second event cannot be directly compared, and how fixed risk factors cannot be predictors, while factors that are not causes can yet be predictors. Integrating all knowledge and combining the best predicting variables will ultimately lead to ways to estimate an individual's recurrence risk and hence to decide on optimal further treatment.

[Recurrence risk in venous thromboembolic disease after anticoagulation discontinuation]

To determine the risk for recurrence of venous thromboembolic disease is essential to decide the optimum duration of treatment. Clinical risk factors, elevated D-dimer after anticoagulation withdrawal and the presence of residual deep vein thrombosis should be considered. In this article the risk factors and the reported risk models are reviewed.

Markers of coagulation, fibrinolysis and inflammation in relation to post-thrombotic syndrome

BACKGROUND

Post-thrombotic syndrome (PTS) occurs in 20-50% of patients after a deep venous thrombosis (DVT). It is difficult to accurately predict which patients will develop PTS. Biomarkers could be a valuable tool for PTS risk assessment.

OBJECTIVES

To investigate whether increased levels of factor (F)VIII, C-reactive protein (CRP) or D-dimer, over time, are associated with the development of PTS in patients after an acute DVT.

METHODS

PTS status was assessed using the Villalta scale. Blood sampling was performed at three points during follow-up.

RESULTS

A cohort of 228 consecutive patients was included after an acute DVT. At T1 (12 months after index DVT), both levels of D-dimer (median 725 ng mL(-1) [interquartile range, IQR 400-1400[ vs. 378 ng mL(-1) [251-652] P=0.004) and CRP (median 3.9 mg L(-1) [IQR 1.6-8.5] vs. 2.4 mg L(-1) [1.0-4.3] P=0.018) were increased in patients with PTS, compared with patients without PTS. Factor (F)VIII was not associated with PTS. In the multivariate logistic regression analysis, varicosities (odds ratio [OR] 13.4 95% confidence interval [CI] 3.0-59.1 P=0.001), a previous ipsilateral DVT (OR 6.3 95% CI 1.5-26.9 P=0.012) and CRP>5 mg L(-1) on T1 (OR 8.0 95% CI 2.4-26.4 P=0.001) were significantly associated with PTS.

CONCLUSIONS

Besides previous ipsilateral DVT and varicosities, CRP>5 mg L(-1) at T1 was strongly and independently associated with PTS. Persistent inflammation rather than hypercoagulability might be the most important etiological factor in PTS, and may be a target for future therapy. The development of a risk score for PTS, including both clinical risk factors and biomarker levels, such as CRP, might be desirable.

Inflammation and coagulation markers and kidney function decline: the Multi-Ethnic Study of Atherosclerosis (MESA)

BACKGROUND

The strength and direction of the associations between inflammation and coagulation biomarkers with kidney disease onset and progression remain unclear, especially in a population-based setting.

STUDY DESIGN

Prospective observational study.

SETTING & PARTICIPANTS

4,966 participants from the Multi-Ethnic Study of Atherosclerosis (MESA) with a cystatin C-based estimate of glomerular filtration rate (eGFR(cys)) >60 mL/min/1.73 m(2) and at least one follow-up measurement of kidney function. All participants were free of cardiovascular disease at entry.

PREDICTOR

We evaluated the associations of C-reactive protein (CRP), interleukin 6 (IL-6), fibrinogen, factor VIII, and d-dimer levels with kidney function decrease.

OUTCOMES & MEASUREMENTS

Kidney function decrease was assessed primarily by repeated measurements of eGFR(cys) over 5 years. Rapid decrease in kidney function was defined as eGFR decrease >3 mL/min/1.73 m(2) per year. Incident low eGFR was defined as the onset of eGFR(cys) <60 mL/min/1.73 m(2) at any follow-up examination and eGFR(cys) decrease ≥1 mL/min/1.73 m(2) per year.

RESULTS

Mean age was 60 years, 39% were white, 52% were women, and 11% had diabetes. Mean eGFR(cys) was 96 mL/min/1.73 m(2) and 7% had albuminuria. Median follow-up was 4.77 years. Higher factor VIII levels (per 1 standard deviation [SD] of biomarker) had the strongest association with kidney function decrease (β = -0.25; 95% CI, -0.38 to -0.12; P < 0.001), followed by IL-6 (β = -0.16; 95% CI, -0.29 to -0.03; P = 0.01), CRP (β = -0.09; 95% CI, -0.22 to 0.03; P = 0.1), and fibrinogen levels (β = -0.09; 95% CI, -0.22 to 0.04; P = 0.2). Each 1-SD higher concentration of IL-6 (OR, 1.15; 95% CI, 1.07-1.23), factor VIII (OR, 1.11; 95% CI, 1.03-1.18), and CRP (OR, 1.09; 95% CI, 1.02-1.16) at baseline was associated significantly with rapid kidney function decrease. Only IL-6 level was associated significantly with incident low eGFR (OR, 1.09; 95% CI, 1.00-1.19).

LIMITATIONS

Observational study design and absence of measured GFR.

CONCLUSIONS

Inflammation and coagulation biomarkers are associated with decreasing kidney function in ambulatory adults without established cardiovascular disease or chronic kidney disease.

Predicting the risk of venous thromboembolism recurrence

Venous thromboembolism (VTE) is a chronic disease with a 30% ten-year recurrence rate. The highest incidence of recurrence is in the first 6 months. Active cancer significantly increases the hazard of early recurrence, and the proportions of time on standard heparin with an APTT ≥ 0.2 anti-X(a) U/mL, and on warfarin with an INR ≥ 2.0, significantly reduce the hazard. The acute treatment duration does not affect recurrence risk after treatment is stopped. Independent predictors of late recurrence include increasing patient age and body mass index, leg paresis, active cancer and other persistent VTE risk factors, idiopathic VTE, antiphospholipid antibody syndrome, antithrombin, protein C or protein S deficiency, hyperhomocysteinemia and a persistently increased plasma fibrin D-dimer. A recommendation for secondary prophylaxis should be individualized based on the risk for recurrent VTE (especially fatal pulmonary embolism) and bleeding. The appropriateness of secondary prophylaxis should be continuously reevaluated, and the prophylaxis stopped if the benefit no longer exceeds the risk.

Elevated factor VIII levels and risk of venous thrombosis

Modern thrombophilia testing fails to identify any underlying prothrombotic tendency in a significant number of patients presenting with objectively confirmed venous thromboemboembolism (VTE). This observation has led to a search for other novel inherited or acquired human thrombophilias. Although a number of putative mechanisms have been described, the evidence behind many of these candidates remains weak. In contrast, an increasing body of work supports the hypothesis that increased plasma factor VIII (FVIII) levels may be important in this context. An association between elevated plasma FVIII levels and VTE was first described in the Leiden Thrombophilia Study (LETS). Subsequently, these conclusions have been supported by an increasing number of independent case-control studies. Cumulatively, these studies have clearly demonstrated that high FVIII levels constitute a prevalent, dose-dependent risk factor for VTE. Furthermore, more recent studies have shown that the risk of recurrent venous thrombosis is also significantly increased in patients with high FVIII levels. In this review, we present the evidence supporting the hypothesis that elevated FVIII levels constitute a clinically important thrombophilia. In addition, we examine the biological mechanisms that may underlie persistently elevated FVIII levels, and the pathways through which high FVIII may serve to increase thrombotic risk.

Recurrent venous thromboembolism: what is the risk and how to prevent it

Venous thromboembolism (VTE) that includes deep vein thrombosis and/or pulmonary embolism is a frequent, severe, and potentially lethal disease. After a first episode, VTE has a strong tendency to recur. While VTE is an acute disease, it may have variable outcomes in early and late phases after initial presentation. Furthermore, the incidence of late, clinically important consequences (postthrombotic syndrome and/or chronic thromboembolic pulmonary hypertension) increases in case of recurrent events. The aims of the present review are (i) to analyze the incidence and risk factors for recurrence of VTE (either those related to the type of first thrombotic event or to the patients), the risks associated with occurrence of recurrent events, and the problems linked to the diagnosis, not always easy, of recurrent events; (ii) to discuss whether or not it is possible to predict the individual risk of recurrence after a first event, by stratifying patients at high or low risk of recurrence, and how this can influence their treatment; (iii) to comment what the current guidelines and guidance suggest/recommend about anticoagulant treatment after a first VTE event and, finally, to propose practical indications on how to manage individual patients affected by VTE.

Risk of early recurrent fetal loss and levels of thrombin-activatable fibrinolysis inhibitor

INTRODUCTION

Though thrombin-activatable fibrinolysis inhibitor (TAFI) may contribute to hypercoagulability during pregnancy, limited data are available on the role of TAFI in women with recurrent fetal loss.

MATERIAL/METHODS

We performed a case-control study aimed at evaluating any possible association between TAFI levels and early recurrent fetal loss (≥ 3, or 2 with at least one normal fetal karyotype, before the 10th week of gestation). 140 women with early recurrent fetal loss and 140 age-matched healthy controls with at least one normal pregnancy were included. The number of miscarriages was 2.59 and occurred at gestational age 6.89 weeks. TAFI levels were determined by a chromogenic assay measuring total potential activatable TAFI.

RESULTS

TAFI levels were significantly lower in early recurrent fetal loss women (12.2 ± 2.3 μg/ml vs 13.2 ± 2.6 μg/ml in healthy controls, p=0.001). ORs of early recurrent fetal loss (crude and adjusted for possible confounding variables) were calculated after stratification of TAFI levels into quartiles. 25/140 (17.8%) early recurrent fetal loss women had TAFI levels above 14.0 μg/ml (4th quartile) vs 44/140 (31.3%) in healthy women (p=0.014). Crude and adjusted ORs of early recurrent fetal loss in women with TAFI levels in the 4th quartile vs those in the reference category (1st quartile=below 11.0 μg/ml) were 0.42 (95%CI: 0.22-0.82) and 0.39 (95%CI: 0.19-0.80), respectively.

CONCLUSIONS

Our study provides evidence that high TAFI levels are associated with reduced risk of early recurrent fetal loss. Further studies are needed to better understand the actual role of TAFI in recurrent fetal loss.

Heparin and warfarin anticoagulation intensity as predictors of recurrence after deep vein thrombosis or pulmonary embolism: a population-based cohort study

To test recommended anticoagulation measures as predictors of 180-day venous thromboembolism (VTE) recurrence, we identified all Olmsted County, MN residents with incident VTE over the 14-year period of 1984-1997, and followed each case (N = 1166) forward in time for VTE recurrence. We tested the activated partial thromboplastin time (APTT), international normalized ratio (INR), and other measures of heparin and warfarin anticoagulation as predictors of VTE recurrence while controlling for baseline and time-dependent characteristics using Cox proportional hazards modeling. Overall, 1026 (88%) and 989 (85%) patients received heparin and warfarin, respectively, and 85 (8%) developed VTE recurrence. In multivariable analyses, increasing proportions of time on heparin with an APTT ≥ 0.2 anti-X(a) U/mL and on warfarin with an INR ≥ 2.0 were associated with significant reductions in VTE recurrence, while the hazard with active cancer was significantly increased. Time from VTE onset to heparin start, duration of overlapping heparin and warfarin, and inferior vena cava (IVC) filter placement were not independent predictors of recurrence. At a heparin dose ≥ 30 000 U/d, the median proportion of time with an APTT ≥ 0.2 anti-X(a) U/mL was 92%, suggesting that routine APTT monitoring and heparin dose adjustment may be unnecessary. In summary, lower-intensity heparin and standard-intensity warfarin anticoagulation are effective in preventing VTE recurrence.