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In this single-center cohort study, we applied a panel of laboratory markers to characterize hemostatic function in 217 consecutive patients that underwent testing for COVID-19 as they were admitted to Linköping University Hospital between April and June 2020. In the 96 patients that tested positive for SARS-CoV-2 (COVID-19+), the cumulative incidences of death and venous thromboembolism were 24.0% and 19.8% as compared to 12.4% (p = 0.031) and 11.6% (p = 0.13) in the 121 patients that tested negative (COVID-19-). In COVID-19+ patients, we found pronounced increases in plasma levels of von Willebrand factor (vWF) and fibrinogen. Excess mortality was observed in COVID-19+ patients with the following aberrations in hemostatic markers: high D-dimer, low antithrombin or low plasmin-antiplasmin complex (PAP) formation, with Odds Ratios (OR) for death of 4.7 (95% confidence interval (CI95) 1.7-12.9; p = 0.003) for D-dimer >0.5 mg/L, 5.9 (CI95 1.8-19.7; p = 0.004) for antithrombin (AT) ˂0.85 kIU/l and 4.9 (CI95 1.3-18.3; p = 0.019) for PAP < 1000 μg/L. Compounding increases in mortality was observed in COVID-19+ patients with combined defects in markers of fibrinolysis and coagulation, with ORs for death of 15.7 (CI95 4.3-57; p < 0.001) for patients with PAP <1000 μg/L and D-dimer >0.5 mg/L and 15.5 (CI95 2.8-87, p = 0.002) for patients with PAP <1000 μg/L and AT ˂0.85 kIU/L. We observed an elevated fraction of incompletely degraded D-dimer fragments in COVID-19+ patients with low PAP, indicating impaired fibrinolytic breakdown of cross-linked fibrin., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Introduction: Data on the prevalence of hypertension and cardiovascular diseases (CVD) among persons with haemophilia (PWH) vary. Sweden has a long tradition of maintaining population-based data registries, and there is extensive follow-up of haemophilia patients due to the use of prophylaxis over decades. We evaluated the prevalence of these diseases among Swedish PWH compared to matched controls using a longitudinal study design., Methods: Data were obtained from the National Patient Registry and linked to records of persons with haemophilia enrolled in the haemophilia centres. For each subject, five gender and age matched controls were identified., Results: We identified 193 (19.7%) diagnoses of hypertension in PWH born in 1978 or earlier over ≥30 years compared with 550 (11.2%) among controls. The median ages and interquartile ranges were 60.0 (42.8, 69.9) and 57.2 (42.6, 70.6) years. The hazard rate (HR) for hypertension, PWH vs. controls, was 2.1, 95% CI: [1.8; 2.5], p < 0.001. The findings were similar in subgroup analyses of patients with non-severe and severe haemophilia with or without HIV and/or viral hepatitis. Angina pectoris was diagnosed in 69 (4.8%) of patients censored at age 75 compared with 311 (4.3%) in controls, and myocardial ischemia in 84 (5.9%) compared with 442 (6.2%). As a cause of death, the HR for myocardial ischemia, comparing PWH and controls, was 0.58, 95% CI: [0.42, 0.80], p = 0.001., Conclusion: Our data support an increased prevalence of hypertension among persons with haemophilia. The prevalence of CVD seems to be similar to that of controls, but with lower mortality., (Copyright © 2019. Published by Elsevier Ltd.)

Venous thromboembolism (VTE) affects approximately 1 per 1000 persons annually. Although patients are increasingly treated with direct oral anticoagulants, many patients continue to be anticoagulated with vitamin K antagonists (VKA). The most important adverse events during VKA treatment, bleeding and the risk of recurrent VTE, are difficult to predict. Global haemostatic assays, such as thrombin generation assays and the viscoelastic whole blood tests thromboelastography (TEG) and thromboelastometry (ROTEM), allow a comprehensive assessment of haemostasis and could potentially predict such side effects. In the present study we compared results from thrombin generation (Calibrated Automated Thrombogram and Innovance ETP assays) and TEG and ROTEM in 84 warfarin-treated patients with primary or recurrent VTE and 87 healthy controls. VKA treatment lead to lagtime prolongation and a lower overall thrombin production, which correlated strongly with INR (Pearson r = 0.89 and r = -0.85, respectively). The reduced thrombin generation of VKA-treated patients was accurately reflected by tissue-factor activated ROTEM (EXTEM) clotting time prolongation (vs. CAT lagtime, r = 0.87). Clot strength or clot formation kinetics were only weakly affected by thrombin generation. Intrinsic pathway activated TEG or ROTEM (INTEM) were not sensitive to the reduced thrombin generation. In conclusion, patients anticoagulated with VKA after VTE showed a reduced plasma thrombin generation that was accurately reflected by tissue factor activated ROTEM. ROTEM provided additional information to thrombin generation, including clot formation kinetics and strength., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Bleeding heterogeneity observed in haemophilia A (HA) may attribute to that the available monitoring methods cannot appropriately reflect the coagulation profile. The present study aimed to develop a global approach by changing the clotting initiation way in rotational thromboelastometry (ROTEM) assay. ROTEM was run in Factor VIII (FVIII)-immune-depleted plasma to which different concentrations of recombinant VIII (rFVIII) had been added, and also in 31 patients with HA. The clotting activators were APTT reagent (1.2 × 10 -3 of the dose used in the original APTT method) and recombinant tissue factor (0.02 pmol/L). In FVIII-immune-depleted plasma spiked with rFVIII, maximum velocity of coagulation reliably mirrored the rFVIII levels. This dose-response disappeared after the samples were pre-incubated with an antibody against TFPI, protein S, activated prothrombin complex concentrate or rFVIIa known to favour the extrinsic activation. In the HA patients with FVIII 0-0.21 IU/mL, APTT and ROTEM outcomes varied in significant correlations to FVIII activity; however, this correlation became non-significant when only samples with FVIII 0-0.05 IU/mL were included. Conclusions: The decreased coagulation in HA mostly result from deficiency/absence of FVIII; other pro-/anti-thrombotic proteins are also influential. The multiple effects may cause a mismatch between bleeding phenotype and FVIII concentrations. The ROTEM assay with the clotting activators i.e., tiny doses of APTT reagent and TF are more effective than the original APTT method as regards the assay sensitivity to influence by VIII activity and also to that by other pro-/anti-thrombotic proteins, showing the whole coagulation picture behind the phenotypic heterogeneity in HA., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Background: Thrombosis and complement activation are pathogenic features of antiphospholipid syndrome (APS). Their molecular link is Plasma carboxypeptidase-B, also known as thrombin activatable fibrinolysis inhibitor (TAFIa), which plays a dual role: anti-fibrinolytic, by cleaving carboxyl-terminal lysine residues from partially degraded fibrin, and anti-inflammatory, by downregulating complement anaphylatoxins C3a and C5a., Aim: To investigate the levels of TAFI (proenzyme) and TAFIa (active enzyme) in relation to complement activation, fibrin clot permeability and fibrinolytic function in clinical and immunological subsets of 52 APS patients and 15 controls., Results: TAFI (p<0.001), TAFIa (p<0.05) and complement factor C5a (p<0.001) were increased, while fibrin permeability (p<0.01) was decreased and clot lysis time (CLT) was prolonged (p<0.05) in APS patients compared to controls. Furthermore, TAFIa was increased (p<0.01) in samples from APS patients affected by arterial thrombosis compared to other APS-phenotypes. Positive associations were found between TAFI and age, fibrinogen and C5a, and between TAFIa and age, fibrinogen and thrombomodulin., Conclusion: TAFI and TAFIa levels were increased in patients with APS as a potential response to complement activation. Interestingly, TAFI activation was associated with arterial thrombotic APS manifestations. Thus, TAFIa may be considered a novel biomarker for arterial thrombosis in APS., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Background: Patients with a history of venous thromboembolism (VTE) seem to have an increased risk of arterial cardiovascular disease (CVD)., Objectives: To evaluate the risk of CVD and overall mortality after a first episode of VTE in women and to assess common risk factors for VTE and CVD., Patients/methods: We performed a cohort study inviting 1433 women with a previous VTE (exposed) and 1402 women without VTE (unexposed). The cohort was derived from TEHS, a Swedish population-based case-control study on risk factors for VTE in women age 18-64years. The women were recruited in 2002-2009. During 2011 information on CVD and mortality was obtained from a questionnaire and from the Swedish Patient Register and the Cause of Death Register. Hazard ratios (HR) for CVD and their 95% confidence intervals (CI) were calculated using Cox regression. In multivariate analyses we adjusted for age, smoking, diabetes mellitus, hypertension and body mass index., Results: 2108 (75%) women (mean age 47±13years) accepted participation. During the total follow up of 11,920 person years 35 (3.2%, 95% CI 0.7-2.1) among the exposed and 14 (1.4%, 95% CI 0.2-4.3) among the unexposed had any CVD event. The adjusted HR for CVD was 2.0 (95% CI 1.1-3.9) the adjusted HR for mortality was 2.3 (95% CI 1.2-4.6) CONCLUSION: Women with a previous VTE had a two-fold increased risk of CVD and overall mortality. Adjusting for cardiovascular risk factors only modestly changed the estimates., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Introduction: The diagnostic potential of whole blood viscoelastic tests thromboelastography (TEG®) and thromboelastometry (ROTEM®) to detect warfarin-induced INR elevation remains elusive., Methods: Viscoelastic tests were performed in 107 patients on warfarin and 89 healthy controls. Tests were activated by kaolin for TEG, and ellagic acid (INTEM) or tissue factor (EXTEM) for ROTEM., Results: Viscoelastic tests revealed significant differences in clotting profiles between controls and warfarin-treated patients. Compared with healthy controls, patients treated with warfarin had prolonged EXTEM clotting and TEG reaction time (p<0.001), both of which were also increased beyond the reference range. Increased INR values correlated with EXTEM CT (Spearman rho=0.87) and TEG R-time (rho=0.73). EXTEM CT had a sensitivity and specificity of 0.89 and 1.00, respectively, to detect elevated INR above 1.2 units, with a positive and negative predictive values (PPV and NPV) of 1.00 and 0.88, respectively. Similarly, TEG R-time had a sensitivity and specificity of 0.86 and 0.87, respectively, with a PPV of 0.89 and a NPV of 0.83. The corresponding receiver operator characteristic area under the curve was 0.99 (95% confidence interval [CI], 0.99 - 1.00) for EXTEM CT and 0.94 (95% CI, 0.91 - 0.97) for TEG R-time., Conclusions: Tissue factor-activated viscoelastic testing (EXTEM) revealed individuals with warfarin-induced INR elevation accurately, while TEG - activated through the intrinsic pathway - still was of acceptable diagnostic value. Further studies are required to evaluate the diagnostic potential of viscoelastic tests in relation to standard laboratory tests in other mixed patient populations, where the PPV and NPV may be inferior., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Objective: The antiphospholipid syndrome (APS) is defined by persistent antiphospholipid antibodies together with thrombosis and/or pregnancy morbidity. We investigated the tightness of fibrin clot and fibrinolytic function in plasma samples from APS patients compared with two control groups., Material and Methods: APS patients (n=49), healthy controls (HC) (n=19) and warfarin-treated nonAPS thrombosis controls (nonAPS-TC) (n=39) were investigated. Fibrin permeability was assessed as the permeability coefficient (Ks) by a flow measurement technique. Additionally, clot density and fibrinolytic function was analysed by a turbidimetric clotting and lysis assay. Fibrin structure was visualised using scanning electron microscopy. Finally, the number of cell-derived microparticles (MPs) in the samples were correlated to fibrin permeability, Results and Conclusions: The Ks value was lower in samples from APS-patients compared to HC and nonAPS-TC (p<0.0001 for both) indicating a less permeable fibrin clot in APS patients. Scanning electron microscopy images confirmed compact fibrin with smaller intrinsic pores and thinner fibers in samples from APS patients as compared to HC. Prolonged fibrinolysis (clot lysis) times were present in the subgroup of APS patients with previous arterial thrombosis (n=15) as compared to HC and to nonAPS-TC (all p-values<0.05). In conclusion, tighter fibrin clots were formed in plasma from APS patients compared with healthy controls and warfarin treated patients with thrombosis of "nonAPS origin". This new observation presents a possible mechanism contributing to the thrombotic predisposition of APS patients. Impaired fibrinolysis, selectively present among APS patients with previous arterial thrombosis, may further aggravate the pro-thrombotic state in this APS subgroup., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Background: It is a matter of debate whether women with an episode of VTE associated with estrogen have a lower risk of recurrence than women with an unprovoked VTE., Objectives: To identify risk factors for recurrent VTE in women and to assess the risk of recurrent VTE associated with combined oral contraceptives (CHC) or menopausal hormone treatment (HT), compared to surgery-related and unprovoked VTE., Patients/methods: A cohort of 974 women aged 18-64 years with a first episode of VTE were followed-up for a median time of 5.2 years. All women were previously included as cases in the Swedish nation-wide case-control study "Thrombo Embolism Hormone Study" (TEHS). Hazard ratios for recurrence were calculated using univariable and multivariable Cox proportional hazards model., Results: A total of 102 patients (10%) suffered from recurrent VTE. The annual rate of recurrence was 1.0% in patients with surgery/cast, 2.0% in patients with CHC/HT and 3.2% in patients with unprovoked first VTE. Adjusted hazards ratio (HRa) for recurrence was 0.35 (95% CI 0.20-0.61) in women with VT provoked by surgery/cast while women with estrogen-associated VTE had a HRa of 0.70 (95% CI 0.43-1.20) compared to women with unprovoked VTE., Conclusion: Women 18-64 years are at low risk of recurrent VTE. Women with hormone associated VTE had a lower risk of recurrence than women with unprovoked VTE, but not as low as surgery/cast provoked VTE., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Background: There is uncertainty regarding the efficacy and incidence of thromboembolic events in patients treated with prothrombin complex concentrates (PCC) for the emergency reversal of warfarin effect., Methods: During 2002 to 2010 we prospectively included 160 patients treated with PCC for emergency reversal of warfarin either for bleeding or because of the need of emergency surgery. A possible relationship to PCC was considered if objectively verified thromboembolism occurred within 7days of PCC administration. Efficacy was adjudicated as good if the bleeding was controlled promptly or if the surgeon did not report excessive perioperative bleeding., Results: We included 160 patients; 72% received PCC for bleeding. The median international normalized ratio (INR) before and after treatment with PCC was 3.5 (interquartile range [IQR] 2.6-5.4) and 1.4 (IQR 1.2-1.6). The mean dose of PCC was 1800IU (IQR 1200-2000). In addition to PCC, 74% of the patients received vitamin K and 34% received plasma. Six patients (3.8%; 95% confidence interval [CI], 1.4-8.0%) developed thromboembolic events (3 strokes, 1 myocardial infarction, 1 deep vein thrombosis, 1 splenic infarction), possibly related to PCC. The clinical efficacy was good in 146 (91%), moderate in 6 (4%), poor in 4 (2.5%) and non-evaluable in 4 patients., Conclusion: The administration of PCC for the emergency reversal of warfarin may be associated with a low risk of thromboembolism. The contribution of an unmasked thrombotic process by cessation of anticoagulation or of activation of coagulation by the hemorrhagic event should also be considered., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Introduction: There is a need for more reliable methods measuring the binding of coagulation factor VIII (FVIII) to von Willebrand factor (VWF) in plasma samples, for use in the clinical routine. We have developed such a method measuring FVIII binding in plasma, utilizing an ELISA system., Materials and Methods: Microtiter plates were coated with a monoclonal antibody (ESH-8), reacting with the C2 domain in FVIII. Thereafter the wells were treated with recombinant FVIII (Kogenate Bayer®). After washing, diluted plasma samples were added and incubated for 1h. Then HRP-conjugated antibodies against VWF were added and used for quantification of bound VWF., Results: A strong signal to VWF concentration response was obtained. Plasma from patients with different types of von Willebrand disease gave frequently diminished responses. However, after correction for the VWF antigen levels, by calculation of FVIII binding/VWF antigen ratio, only the patients with known von Willebrand disease type 2N (n = 4) had clearly abnormal results. The FVIII binding in 40 healthy individuals was determined as 1.08 ± 0.48 U/mL (SD). After correction for the VWF antigen levels the result was 0.94 ± 0.15. Thus, the SD declined substantially by this correction. The within-series CV and between-series CV were determined as 6.8 and 11.3%, respectively., Conclusions: We have established a simple and reliable method to detect decreased binding of FVIII to von Willebrand factor in plasma samples. The method can conveniently be used to study large populations, as well as finding minor binding defects in patients., (Copyright © 2010 Elsevier Ltd. All rights reserved.)