von Willebrand factor (VWF) is a multimeric glycoprotein involved in primary hemostasis, recruiting platelets to the site of damaged vessels and acting as a carrier for factor VIII. Quantitative or... Show morevon Willebrand factor (VWF) is a multimeric glycoprotein involved in primary hemostasis, recruiting platelets to the site of damaged vessels and acting as a carrier for factor VIII. Quantitative or qualitative alterations of VWF cause von Willebrand disease (VWD), an inherited bleeding disorder. Conversely, increased VWF levels have been associated with various thrombotic conditions. In this thesis, we investigated the dual role of VWF in bleeding and thrombosis, focusing on VWD and deep vein thrombosis (DVT). In the first part of the thesis, we demonstrated the utility of in silico tools and heterologous cell systems in proving the disease-causing role of VWF variants thus contributing to the confirmation of patient diagnoses. In the second part, we focused on type 3 VWD, the most severe form of this disorder caused by a lack of VWF. We showed that patients with missense variants had a higher VWF propeptide/VWF antigen ratio than carriers of VWF null alleles. This suggested that secreted VWF is rapidly removed from circulation in these patients. Subsequently, we estimated the prevalence of VWF neutralizing and non-neutralizing antibodies, confirming that they are rare side effects of replacement therapy. We also demonstrated that the detection of epitope-specific VWF inhibitors is affected by the test used. In the last part of the thesis, we evaluated the role of ADAMTS13-VWF equilibrium in the pathogenesis of DVT, showing that a slight decrease in ADAMTS13 activity, particularly when combined with increased VWF levels, increases DVT risk. We then sequenced ADAMTS13, VWF, and F8 genes and confirmed that DVT patients carrying a rare ADAMTS13 variant exhibited lower ADAMTS13 activity than non-carriers. Show less
Hany, M.; Abouelnasr, A.A.; Agayby, A.S.S.; Abdelsattar, A.; Torensma, B. 2023
Obesity increases the risk of developing venous thromboembolic disease (VTE), including deep vein thrombosis (DVT), pulmonary embolism (PE), and portomesenteric vascular thrombosis (PMVT) [1]. Des... Show moreObesity increases the risk of developing venous thromboembolic disease (VTE), including deep vein thrombosis (DVT), pulmonary embolism (PE), and portomesenteric vascular thrombosis (PMVT) [1]. Despite the widespread application of laparoscopy in bariatric metabolic surgery (BMS), VTE is still encountered, with the incidence of symptomatic DVT, PE, and PMVT ranging from 0.2 to 3%, 0.1 to 2%, and 0.3% to 1%, respectively [1, 2]. We provide a brief communication on the current evidence and guidelines derived from our opinion formulated after 15 years of practice and, thereby, postulate novel suggestions for a new regimen. Show less
Venous thromboembolism (VTE) encompasses pulmonary embolism (PE) and deep vein thrombosis (DVT). DVT most commonly occurs in the deep veins of the lower extremity but can also occur in the veins of... Show moreVenous thromboembolism (VTE) encompasses pulmonary embolism (PE) and deep vein thrombosis (DVT). DVT most commonly occurs in the deep veins of the lower extremity but can also occur in the veins of upper extremity, abdomen and cerebrum. As symptoms of VTE are nonspecific, the diagnosis of VTE is based on diagnostic tests, including clinical decision rules (CDR), D-dimer tests and imaging. Although the diagnostic management of VTE has greatly advanced in recent years with the introduction of novel CDRs and high-sensitive D-dimer tests, the diagnosis may still be challenging in certain settings. The latter is mainly caused by the indirect way of thrombus visualisation by current imaging tests, such as by showing incompressibility with compression ultrasonography (CUS) or a filling defect on contrast-enhanced computed tomography (CT) or magnetic resonance imaging (MRI).This thesis focuses on challenging settings for diagnosing VTE, including suspected recurrent ipsilateral DVT, upper extremity DVT, cerebral vein thrombosis and portal vein thrombosis. We studied a novel imaging technique called Magnetic Resonance Non-Contrast Thrombus Imaging (MR-NCTI) and its application in these different VTE settings. Show less
Giustozzi, M.; Valerio, L.; Agnelli, G.; Becattini, C.; Fronk, E.M.; Klok, F.A.; ... ; Barco, S. 2021
Introduction: Sex and the presence of specific provoking risk factors, along with age, influence the presentation and prognosis of venous thromboembolism (VTE). We investigated the presentation,... Show moreIntroduction: Sex and the presence of specific provoking risk factors, along with age, influence the presentation and prognosis of venous thromboembolism (VTE). We investigated the presentation, course and quality of life in women and men with acute VTE classified according to their VTE provoking factors.Methods: PREFER in VTE is an international, non-interventional registry of patients with a first episode of acute symptomatic VTE. Baseline provoking factors were classified as follows: major transient, minor transient, active cancer, and none identifiable. The primary outcome was recurrent VTE. Quality of life and treatment satisfaction were secondary outcomes.Results: Of 3,455 patients with acute VTE, 1,623 (47%) were women. The mean age at the time of VTE was 61 (SD 18) in women, 60 (SD 15) in men. The distribution of provoking risk factors was similar between sexes, despite a tendency for higher frequency of minor and major transient risk factors in women, and cancer or unprovoked VTE in men. At 12-month follow-up, VTE recurrence was reported in 74 (6.5%) women and 80 (6.4%) men (absolute risk difference-0.1%, 95% CI-1.9%; +2.1%). In patients with unprovoked VTE, the VTE recurrence rate was 38/612 (6.2%) in women and 53/798 (6.6%) in men (absolute risk difference-0.4, 95% CI-3.0; +2.1%). Multivariable Cox regressions confirmed the absence of sex differences. Quality of life and treatment satisfaction scores one year after VTE were lower in women than in men irrespective of the provoking risk factors (p<0.001 for both scores).Conclusions: Despite differences in the provoking risk factors for VTE, women and men had a similar rate VTE recurrence at one year. After acute VTE, women had lower quality of life and treatment satisfaction scores. Show less
Hamer, H.M.; Stroobants, A.K.; Bavalia, R.; Ponjee, G.A.E.; Klok, F.A.; Hulle, T. van der; ... ; Middeldorp, S. 2021
Introduction: For exclusion of pulmonary embolism (PE) clinical decision rules in combination with a D-dimer assay are applied. Currently available D-dimer assays are not standardized and it is... Show moreIntroduction: For exclusion of pulmonary embolism (PE) clinical decision rules in combination with a D-dimer assay are applied. Currently available D-dimer assays are not standardized and it is unknown whether these differences have an impact on diagnostic management of suspected PE. Therefore, the aim is to explore differences between D-dimer assays and their impact on diagnostic outcome. Methods: Data from all patients included in the YEARS study were collected. The YEARS study is a prospective, multicentre, cohort outcome study evaluating 3462 patients with suspected PE in which four different D-dimer assays were applied (Liatest, Innovance, Tinaquant, Vidas). Median D-dimer concentrations were calculated for each D-dimer assay. Sensitivity, specificity, PPV and NPV for detection of PE of all four assays were determined in patients without YEARS items and in those with >1 YEARS items (i.e. symptomatic deep vein thrombosis, haemoptysis, and whether PE is the most likely diagnosis). Results: A total of 1323, 1100, 768 and 271 D-dimer concentrations were collected using the Liatest Innovance, Tinaquant and Vidas assay, respectively. Median D-dimer concentrations differed significantly between assays, with lowest values in the Tinaquant assay. In patients without YEARS items using a cutoff level of 1000 ng/mL, the NPV varied from 99,5 to 100%. In patients with >1 YEARS items using a 500 ng/mL cutoff, the NPV varied from 97,0 to 100% depending on the assay. Conclusions: The overall high NPV for all assays demonstrates the clinical value of the D-dimer assay. However, these results confirm differences between D-dimer assays, which have an impact on follow-up imaging. This emphasizes the need for standardization of D-dimer assays. Show less
Pagliari, M.T.; Boscarino, M.; Cairo, A.; Mancini, I.; Martinelli, I.; Bucciarelli, P.; ... ; Peyvandi, F. 2021
Background: Deep vein thrombosis (DVT) is a common multi-factorial disease with a partially understood aetiology. Although the roles of high factor (F)VIII and von Willebrand factor (VWF) levels... Show moreBackground: Deep vein thrombosis (DVT) is a common multi-factorial disease with a partially understood aetiology. Although the roles of high factor (F)VIII and von Willebrand factor (VWF) levels are recognized, that of ADAMTS13 is still unclear.Aim: To assess the association between ADAMTS13 activity levels, VWF antigen (VWF:Ag) and FVIII coagulant activity (FVIII:C) levels and DVT.Materials and methods: 365 Italian DVT patients and 292 ageand sex-matched controls were considered. Plasma ADAMTS13 activity was measured using FRETS-VWF73 assay. VWF:Ag and FVIII:C were measured using immunoassay and one-stage clotting assay (ACL TOP analyzer), respectively. Quartile analyses were performed to evaluate the individual association between ADAMTS13 activity, VWF:Ag, FVIII:C and DVT. The combined effect of high VWF levels ( 4th quartile) and low ADAMTS13 levels (< 1st quartile) was evaluated using binary variables. All models were ageand sex-adjusted. Estimated risks were reported as Odds ratio (OR) with 95% confidence intervals (CI).Results: ADAMTS13 activity was lower in DVT patients (94% vs. 98% of controls). Patients with an ADAMTS13 activity <1st quartile (86%) showed a 1.6-fold increased risk of DVT (95%CI, 1.05-2.55). The combination of low ADAMTS13 activity and high VWF:Ag levels was associated with a 15-fold increased risk (95%CI, 7.80-33.80). VWF:Ag and FVIII:C were associated to DVT with a dose-response relationship.Conclusions: ADAMTS13 activity < 86% was associated with a moderate risk of DVT. The co-presence of low ADAMTS13 activity and high VWF levels resulted in a strong synergistic effect on DVT risk. The association of VWF:Ag and FVIII:C with DVT was confirmed. Show less
Klok, F.A.; Kruip, M.J.H.A.; Meer, N.J.M. van der; Arbous, M.S.; Gommers, D.; Kant, K.M.; ... ; Endeman, H. 2020
Introduction: We recently reported a high cumulative incidence of thrombotic complications in critically ill patients with COVID-19 admitted to the intensive care units (ICUs) of three Dutch... Show moreIntroduction: We recently reported a high cumulative incidence of thrombotic complications in critically ill patients with COVID-19 admitted to the intensive care units (ICUs) of three Dutch hospitals. In answering questions raised regarding our study, we updated our database and repeated all analyses.Methods: We re-evaluated the incidence of the composite outcome of symptomatic acute pulmonary embolism (PE), deep-vein thrombosis, ischemic stroke, myocardial infarction and/or systemic arterial embolism in all COVID-19 patients admitted to the ICUs of 2 Dutch university hospitals and 1 Dutch teaching hospital from ICU admission to death, ICU discharge or April 22nd 2020, whichever came first.Results: We studied the same 184 ICU patients as reported on previously, of whom a total of 41 died (22%) and 78 were discharged alive (43%). The median follow-up duration increased from 7 to 14 days. All patients received pharmacological thromboprophylaxis. The cumulative incidence of the composite outcome, adjusted for competing risk of death, was 49% (95% confidence interval [CI] 41-57%). The majority of thrombotic events were PE (65/75; 87%). In the competing risk model, chronic anticoagulation therapy at admission was associated with a lower risk of the composite outcome (Hazard Ratio [HR] 0.29, 95%CI 0.091-0.92). Patients diagnosed with thrombotic complications were at higher risk of all-cause death (HR 5.4; 95%CI 2.4-12). Use of therapeutic anticoagulation was not associated with all-cause death (HR 0.79, 95%CI 0.35-1.8).Conclusion: In this updated analysis, we confirm the very high cumulative incidence of thrombotic complications in critically ill patients with COVID-19 pneumonia. Show less
Klok, F.A.; Kruip, M.J.H.A.; Meer, N.J.M. van der; Arbous, M.S.; Gommers, D.A.M.P.J.; Kant, K.M.; ... ; Endeman, H. 2020
Introduction: COVID-19 may predispose to both venous and arterial thromboembolism due to excessive inflammation, hypoxia, immobilisation and diffuse intravascular coagulation. Reports on the... Show moreIntroduction: COVID-19 may predispose to both venous and arterial thromboembolism due to excessive inflammation, hypoxia, immobilisation and diffuse intravascular coagulation. Reports on the incidence of thrombotic complications are however not available.Methods: We evaluated the incidence of the composite outcome of symptomatic acute pulmonary embolism (PE), deep-vein thrombosis, ischemic stroke, myocardial infarction or systemic arterial embolism in all COVID-19 patients admitted to the ICU of 2 Dutch university hospitals and 1 Dutch teaching hospital.Results: We studied 184 ICU patients with proven COVID-19 pneumonia of whom 23 died (13%), 22 were discharged alive (12%) and 139 (76%) were still on the ICU on April 5th 2020. All patients received at least standard doses thromboprophylaxis. The cumulative incidence of the composite outcome was 31% (95%CI 20-41), of which CTPA and/or ultrasonography confirmed VTE in 27% (95%CI 17-37%) and arterial thrombotic events in 3.7% (95%CI 0-8.2%). PE was the most frequent thrombotic complication (n = 25, 81%). Age (adjusted hazard ratio (aHR) 1.05/per year, 95%CI 1.004-1.01) and coagulopathy, defined as spontaneous prolongation of the prothrombin time > 3 s or activated partial thromboplastin time > 5 s (aHR 4.1, 95%CI 1.9-9.1), were independent predictors of thrombotic complications.Conclusion: The 31% incidence of thrombotic complications in ICU patients with COVID-19 infections is remarkably high. Our findings reinforce the recommendation to strictly apply pharmacological thrombosis prophylaxis in all COVID-19 patients admitted to the ICU, and are strongly suggestive of increasing the prophylaxis towards high-prophylactic doses, even in the absence of randomized evidence. Show less
Introduction: We recently proposed a scale for assessment of patient-relevant functional limitations following an episode of venous thromboembolism (VTE). Further development of this post-VTE... Show moreIntroduction: We recently proposed a scale for assessment of patient-relevant functional limitations following an episode of venous thromboembolism (VTE). Further development of this post-VTE functional status (PVFS) scale is still needed.Methods: Guided by the input of VTE experts and patients, we refined the PVFS scale and its accompanying manual, and attempted to acquire broad consensus on its use.Results: A Delphi analysis was performed involving 53 international VTE experts with diverse scientific and clinical backgrounds. In this process, the number of scale grades of the originally proposed PVFS scale was reduced and descriptions of the grades were improved. After these changes, a consensus was reached on the number/definitions of the grades, and method/timing of the scale assessment. The relevance and potential impact of the scale was confirmed in three focus groups totaling 18 VTE patients, who suggested additional changes to the manual, but not to the scale itself. Using the improved manual, the.-statistics between PVFS scale self-reporting and its assessment via the structured interview was 0.75 (95%CI 0.58-1.0), and 1.0 (95%CI 0.83-1.0) between independent raters of the recorded interview of 16 focus groups members.Conclusion: We improved the PVFS scale and demonstrated broad consensus on its relevance, optimal grades, and methods of assessing among international VTE experts and patients. The interobserver agreement of scale grade assignment was shown to be good-to-excellent. The PVFS scale may become an important outcome measure of functional impairment for quality of patient care and in future VTE trials. Show less
The main objectives of therapeutic trials in venous thromboembolism (VTE) are to prevent recurrent VTE, major bleeding and death. While these outcomes are indeed highly relevant, they are also rare... Show moreThe main objectives of therapeutic trials in venous thromboembolism (VTE) are to prevent recurrent VTE, major bleeding and death. While these outcomes are indeed highly relevant, they are also rare and do not fully capture the overall functional outcome of VTE patients. Importantly, functional limitations after VTE are prevalent after both deep vein thrombosis and pulmonary embolism occurring in up to 50% of patients. These post-VTE syndromes are associated with a decreased quality of life, higher risk of depressive disorders, unemployment and increased utilization of healthcare resources. Because of the major impact of functional limitations on individual patients and society as a whole, development of tools able to capture functional outcomes in clinical trials are urgently needed. We anticipate that a standardized post-VTE functional status scale will aid in demarcating effective and ineffective VTE therapies on functional outcomes in trials with appropriately powered sample sizes, as well as pave the road for value-based healthcare. The scale that we have in mind covers the entire spectrum of functional outcomes ranging from no symptoms to death. Moreover, it focuses on both limitations in usual activity as well as changes in lifestyle. The scale is not meant to replace current diagnostic or prognostic scores for post-VTE syndromes, but to be used as an outcome measure to evaluate the overall consequences of VTE on functional status. This review is a call for action to the VTE community to join forces and support further development of the proposed scale, a process of which we summarize the necessary steps. Show less
