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The inferior vena cava (IVC) and superior vena cava are the main conduits of the systemic venous circulation into the right atrium. Developmental or procedural interruptions of vena cava might predispose to stasis and deep vein thrombosis (DVT) distal to the anomaly and may impact the subsequent rate of pulmonary embolism (PE). This study aimed to review the various etiologies of developmental or procedural vena cava interruption and their impact on venous thromboembolism. A systematic search was performed in PubMed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines per each clinical question. For management questions with no high-quality evidence and no mutual agreements between authors, Delphi methods were used. IVC agenesis is the most common form of congenital vena cava interruption, is associated with an increased risk of DVT, and should be suspected in young patients with unexpected extensive bilateral DVT. Surgical techniques for vena cava interruption (ligation, clipping, and plication) to prevent PE have been largely abandoned due to short-term procedural risks and long-term complications, although survivors of prior procedures are occasionally encountered. Vena cava filters are now the most commonly used method of procedural interruption, frequently placed in the infrarenal IVC. The most agreed-upon indication for vena cava filters is for patients with acute venous thromboembolism and coexisting contraindications to anticoagulation. Familiarity with different forms of vena cava interruption and their local and systemic adverse effects is important to minimize complications and thrombotic events., Competing Interests: Dr. Bikdeli reports that he was a consulting expert, on behalf of the plaintiff, for litigation related to two specific brand models of IVC filters. Dr. Bikdeli has not been involved in the litigation in 2022 or 2023 nor has he received any compensation in 2022 or 2023. Dr. Bikdeli reports that he is a member of the Medical Advisory Board for the North American Thrombosis Forum, and serves in the Data Safety and Monitory Board of the NAIL-IT trial funded by the National Heart, Lung, and Blood Institute, and Translational Sciences. Dr. Mena-Hurtado was consultant for Abbott, cook, penumbra, Optum labs. Dr. Hanke received consulting fees from Bayer and Janssen. Dr. Bashir has an equity interest in Thrombolex, Inc. He is also supported by an NHLBI grant under the SBIR grant mechanism. Dr. Wasan received speaker fees from Janssen and is on the steering committee of the C-TRACT trial. Dr. Lang is receiving research support from AOP-Health, Janssen, and Neutrolis, and consulting fees from AOP-Health, Janssen, and Medtronic. Dr. Giri is on advisory boards and receives research funds from the institutions of Abiomed, Boston Scientific, Abbot Vascular, Recor Medical, and Inari Medical. Dr. Middeldorp reports grants and personal fees from GSK, Aspen, Pfizer, Daiichi-Sankyo, Bayer, Pfizer, Boehringer-Ingelheim, Portola/Alexion, Astra Zeneca, Abbvie, Pfizer/Bristol-Meyers Squibb, Norgine, Viatris, and Sanofi, all outside the submitted work. Dr. Krumholz received expenses and/or personal fees from UnitedHealth, Element Science, Aetna, Reality Labs, Tesseract/4Catalyst, the Siegfried and Jensen Law Firm, Arnold and Porter Law Firm, Martin/Baughman Law Firm, and F-Prime; is a cofounder of Refactor Health and HugoHealth; and contracts through Yale New Haven Hospital from the Centers for Medicare & Medicaid Services and through Yale University from Johnson & Johnson. Dr. Piazza has received research support from Bristol-Myers Squibb/Pfizer Alliance, Bayer, Janssen, Alexion, Amgen, and Boston Scientific Corporation, and consulting fees from Bristol-Myers Squibb/Pfizer Alliance, Boston Scientific Corporation, Janssen, NAMSA, Prairie Education and Research Cooperative, Boston Clinical Research Institute, and Amgen. Other authors report no disclosures., (Thieme. All rights reserved.)

Background  The origin of autoantibodies in patients with antiphospholipid syndrome (APS) is unknown. The gut microbiome contributes to autoimmunity and contains peptide homologues to the main APS autoantigen, which affect disease activity in animal models. Alteration of the gut microbiota with vancomycin diminishes disease activity in mice but no data on the effect of gut microbiota alteration in APS patients are available to date. Objective  To evaluate whether the gut microbiome affects disease activity in human APS. Methods  This was a pre-post design intervention study in APS patients with stable disease and no gastrointestinal comorbidity. Subjects received oral vancomycin, 500 mg four times daily for 7 days, previously shown to alter gut microbiota composition without systemic effects. Disease activity was assessed at four time points by measuring a panel of clinical phenotype-related biomarkers: antiphospholipid antibodies (APLAs), complement and inflammation markers, and hemostatic parameters. The primary outcome was the composite of the biomarker panel determined by multilevel principal component analysis. Results  A total of 15 subjects completed the study. The primary outcome, the first principal component of the biomarker panel data, was significantly different after 7 days of vancomycin treatment ( p  = 0.03), but not at day 42. APLA titers were unaffected. Unexpectedly, 4 out of 15 patients were negative for APLAs at baseline. In a post-hoc analysis, there was a prolonged effect for subjects with positive antibodies at baseline ( p  = 0.03). In subjects with negative APLAs at baseline, the intervention showed no effect. Conclusion  The intestinal microbiome affects the biochemical disease activity in APS patients. The mechanism is yet unknown but appears to be APS-specific., Competing Interests: Conflicts of Interest M.L. reports a research grant from GSK and consulting fees from GSK and AstraZeneca outside of the submitted work. M.C. has received financial support for research from Bayer, CSL Behring, Roche, UniQure, and Novo Nordisk; honoraria for consulting or lecturing from Alexion, Bayer, CSL Behring, Sobi, and Viatris. M.N. is founder and a member of the Scientific Advisory Board of Caelus Pharmaceuticals, The Netherlands; however, none of these possible conflicts of interest bear direct relations to the outcomes of this specific study. S.M. reports grants from GSK and Aspen; grants and personal fees from Daiichi-Sankyo, Bayer, Pfizer, and Boehringer Ingelheim; and personal fees from Portola/Alexion, AbbVie, Pfizer/Bristol-Meyers Squibb, Norgine, Viatris, and Sanofi, outside of the submitted work., (The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. ( https://creativecommons.org/licenses/by/4.0/ ).)

Venous thromboembolism (VTE) remains the leading cause of maternal mortality in pregnancy and the postpartum period. In addition to the higher pregnancy-associated baseline VTE risk, there are several well-established risk factors that can further increase the risk of VTE. At present, a thorough interrogation of these risk factors remains our only tool for estimating which pregnant people may be at an increased risk of VTE, and thus potentially benefit from thromboprophylaxis. However, an important knowledge gap still exists surrounding the duration of increased risk and the interaction of risk factors with each other. Furthermore, up to now, once significant risk has been established, prevention strategies have been largely based on expert opinion rather than high-quality data. Recent trials have successfully bridged a proportion of this knowledge gap; however, the challenge of conducting high-quality clinical trials with pregnant people remains. In this article, we provide an update on the recent evidence surrounding VTE risk factors in pregnancy while concurrently outlining knowledge gaps and current approaches to VTE prevention., Competing Interests: EOR and RF have no conflicts of interest.MB: Support for attending meetings and/or travel: SOBI; Participation on a Data Safety Monitoring Board or Advisory Board: DSMB.SM: reports personal fees and grants outside the submitted work: Pfizer, Boehringer-Ingelheim, Bayer, Portola/Alexion/Astra Zeneca, Abbvie, Norgine, BMS Pfizer, Viatris, Sanofi.FNÁ: Principal Investigator, HRB Definitive Interventions and Feasibility Awards (DIFA) 2017 (DIFA-2017-040) 60 months. Role: PI; Value: €657,699.00: Health Research Board (Ireland); Collaborator; Research funding for translational project (investigator-initiated study (IIS)); paid to institution; unrelated to this project: Sanofi; Principal Investigator; Research funding for translational project (investigator-initiated study (IIS)); paid to institution; unrelated to this project: Daiichi-Sankyo; PI on a research grant (paid to institution; unrelated to this project): KEDS-2018-004: Irish Health Research Board; Collaborator; Research funding for translational project (investigator-initiated study (IIS)); paid to institution; unrelated to this project: Bayer; “A method of diagnosing and/or prognosing preeclampsia” University College Dublin. Inventor(s): MAGUIRE, Patricia, SZKLANNA, Paulina, NÍ ÁINLE, Fionnuala (Filed 30/03/2020): European Application No 20166826.6; Leadership or fiduciary role in other board, society, committee or advocacy group, paid or unpaid:- Past Member of World Thrombosis Day International Steering Committee (http://www.worldthrombosisday.org/) (until 2021)- Director at Large and Member, INVENT Council (International Network of VENous Thromboembolism Clinical Research Networks) https://www.invent-vte.com/ - Co-director, SPHERE Research Group, UCD Conway Institute- Director, INViTE (Irish Network for VTE Research)- Co-Founder (2016) and Member, Executive Committee of VTE Ireland, a National Clinical VTE Working Group- Appointed to Advisory Committee for Human Medicine (ACHM) of the Health Products Regulatory Authority (HPRA) January 2016, Reappointed 2021- Member of “Preventing venous thromboembolism in hospitals” Collaborative Advisory Group. Established May 2016; Chaired by Dr Philip Crowley, National Director, Health Services Executive Quality Improvement Directorate- Board member, Thrombosis Ireland Patient Organization and Charity (Oct 2019-present)- Oct 2019-present: Irish Haematology Society Transfusion Special interest Subcommittee- Oct 2019-present: Irish Haematology Society Coagulation Special interest Subcommittee, (Thieme. All rights reserved.)

Background  For most patients with newly diagnosed atrial fibrillation (AF), direct oral anticoagulants (DOACs) are preferred over vitamin K antagonists. However, there is concern that the lack of monitoring may impair therapy adherence and therefore the anticoagulant effect. Objective  To assess 1-year DOAC nonadherence in patients with AF and a treatment indication of at least 1 year in the Dutch health care setting, and to identify predictors of nonadherence. Methods  We performed a near-nationwide historical cohort study in patients with a novel DOAC indication for AF. Data were obtained from a pharmacy database, covering 65% of all outpatient prescriptions dispensed in the Netherlands. The 1-year nonadherence was assessed by the proportion of days covered; the threshold was set at <80%. Robust Poisson regression analyses were performed to identify predictors of nonadherence. Results  A total of 46,211 patients were included and the 1-year nonadherence was 6.5%. We identified male sex (risk ratio [RR] 1.23, 95% confidence interval [CI]: 1.15-1.33), younger age (age ≥60 to <70 years: RR: 1.15, 95% CI: 1.00-1.33, age <60 years: RR: 2.22, 95% CI: 1.92-2.57; reference age ≥85 years), a reduced DOAC dose (RR: 1.10, 95% CI: 1.00-1.22), a twice-daily dosing regimen (RR: 1.21, 95% CI: 1.12-1.30), and treatment with apixaban (RR: 1.16, 95% CI: 1.06-1.26, reference rivaroxaban) or dabigatran (RR: 1.25, 95% CI: 1.14-1.37) as independent predictors of 1-year nonadherence. Conclusion  One-year nonadherence to DOACs was low yet relevant in patients with AF newly prescribed a DOAC. Understanding the predictors for nonadherence may help identify patients at risk., Competing Interests: Conflict of Interest T.A.C.d.V. reports nonfinancial support from Daiichi Sankyo, and speaker fees from both Bristol-Myers Squibb and speakers bureaus; all unrelated to this work. He also reports that he is being considered for the adjudication committee of the LIMIT & DANCE trials, which are sponsored by the Population Health Research Institute. K.M., K.M.v.d.W., and H.v.B. are employees of IQVIA, and H.X. is a former employee. J.R.d.G. reports research grants to his institution from AtriCure, Bayer, Boston Scientific, Daiichi Sankyo, Johnson & Johnson, and Medtronic; and consultancy/speaker fees from Atricure, Bayer, Berlin Chemie, Daiichi Sankyo, Menarini, Novartis, and Servier, all unrelated to this work. S.M. reports grants from GSK, BMS/Pfizer, Aspen, Daiichi Sankyo, Bayer, Boehringer Ingelheim, Sanofi, and Portola/Alexion, all unrelated to this work. F.A.K. reports grants or contracts from Bayer, BMS, BSCI, MSD, Leo Pharma, Actelion, Farm-X, The Netherlands Organisation for Health Research and Development, The Dutch Thrombosis Association, The Dutch Heart Foundation, and the Horizon Europe Program, all unrelated to this work and paid to his institution. M.E.W.H. reports speaker fees from BMS/Pfizer, Daiichi Sankyo, Bayer, Boehringer Ingelheim, and a research grant from Netherlands Federation of Anticoagulation clinics, all unrelated to this work. M.V.H. reports research grants from Dutch Healthcare Fund, Dutch Heart Foundation, Boehringer-Ingelheim, Pfizer-BMS, Bayer Health Care, and Leo Pharma, all unrelated to this work. The other authors have no conflicts of interest to declare., (The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. ( https://creativecommons.org/licenses/by/4.0/ ).)

Gender dysphoria refers to psychological distress that results from an incongruence between gender identity and sex assigned at birth. Administration of sex hormones is most often used as a first step to develop and maintain physical characteristics consistent with gender identity. Gender-affirming hormone treatment is considered beneficial for the quality of life and reduction of depression. However, estrogen and androgen-lowering hormone therapies used in transwomen are in particular associated with increased risk of venous thromboembolism. In this review, introduced by a clinical case, we provide an overview of the currently available medical therapies in transgender medicine, and put the associated increased risk of venous thromboembolism into perspective., Competing Interests: The authors declare that they have no conflict of interest., (Thieme. All rights reserved.)

Background:  Andexanet alfa (andexanet) is approved for specific anticoagulation reversal in patients with life-threatening or uncontrolled bleeding during treatment with rivaroxaban or apixaban. There is limited experience with andexanet in patients with acute bleeding on edoxaban., Methods:  Patients with acute major bleeding within 18 hours of edoxaban intake were prospectively enrolled. Patients received a bolus and 2-hour follow-on infusion of andexanet. The co-primary efficacy outcomes were change in antifactor Xa activity and the percentage of patients achieving excellent or good hemostasis, 12 hours after andexanet treatment. Efficacy was analyzed in patients with confirmed major bleeding and baseline antifactor Xa activity ≥40 ng/mL. Safety was analyzed in all patients., Results:  Thirty-six patients (mean age: 82 years, 61.1% male and 91.7% with atrial fibrillation) with acute major bleeding on edoxaban received andexanet. The primary site of bleeding was intracranial in 29 patients (80.6%). In the efficacy population ( n  = 28), median antifactor Xa activity decreased from 121.1 (interquartile range [IQR]: 70.3-202.4) ng/mL at baseline to 24.0 (IQR: 77.7-83.7) ng/mL at the end of andexanet bolus (median decrease: 68.9%, 95% confidence interval [CI]: 56.1-77.7%). Excellent or good hemostasis at 12 hours was achieved in 78.6% (95% CI: 59.0-91.7%) of patients. Within 30 days, four patients (11.1%) experienced a thrombotic event and four others (11.1%) died., Conclusion:  In patients with acute major bleeding on edoxaban, andexanet significantly decreased antifactor Xa activity. Hemostatic efficacy was similar to that observed in patients with bleeding on rivaroxaban or apixaban. Thrombotic events occurred at a rate expected in such patients., Competing Interests: A.P.B and L.X. have nothing to report. J.W.E. reports honoraria and/or research grants from AstraZeneca, Bayer, Boehringer Ingelheim, Bristol-Myers Squibb, Daiichi Sankyo Inc., Pfizer, and Servier. S.M. reports grant support from Daiichi Sankyo Inc., Bayer, and Aspen Pharma; serving on advisory boards for Bayer, Bristol-Myers Squibb/Pfizer, Boehringer Ingelheim, and Portola; receiving lecture fees from Portola; and serving on an adjudication committee for AbbVie. T.J.M. reports executive/steering committee payments for ANNEXA-I and ENRICH-AF studies from PHRI/McMaster University; consulting income from CSL Behring; and grants from NHLBI and Genentech. M.C. reports serving on a data and safety monitoring board for Bayer; receiving personal funding or serving on advisory boards for Bristol Myers Squibb Canada, CSL Behring, Servier Canada, Asahi Kasei, Precision Biologics, and Hemostasis Reference Laboratory; preparation of educational material and/or presentations and/or moderation of sessions for Pfizer, Alexion, CSL Behring, and Diagnostica Stago; and individual stock ownership for Alnylam. P.Y. reports former employment with Portola Pharmaceuticals Inc., now Alexion, AstraZeneca Rare Disease. P.C. reports former employment with Portola Pharmaceuticals Inc., now Alexion, AstraZeneca Rare Disease. G.L. reports employment with Portola Pharmaceuticals Inc., now Alexion, AstraZeneca Rare Disease. S.J.C. reports institutional research grants and honoraria from Boehringer Ingelheim, Portola/Alexion Pharmaceuticals, Bristol-Myers Squibb/Pfizer, Bayer, and Daiichi Sankyo Inc., (The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/).)

Background: Venous thromboembolism constitutes substantial health care costs amounting to approximately 60 million euros per year in the Netherlands. Compared with initial hospitalization, home treatment of pulmonary embolism (PE) is associated with a cost reduction. An accurate estimation of cost savings per patient treated at home is currently lacking., Aim: The aim of this study was to compare health care utilization and costs during the first 3 months after a PE diagnosis in patients who are treated at home versus those who are initially hospitalized., Methods: Patient-level data of the YEARS cohort study, including 383 normotensive patients diagnosed with PE, were used to estimate the proportion of patients treated at home, mean hospitalization duration in those who were hospitalized, and rates of PE-related readmissions and complications. To correct for baseline differences within the two groups, regression analyses was performed. The primary outcome was the average total health care costs during a 3-month follow-up period for patients initially treated at home or in hospital., Results: Mean hospitalization duration for the initial treatment was 0.69 days for those treated initially at home ( n  = 181) and 4.3 days for those initially treated in hospital ( n  = 202). Total average costs per hospitalized patient were €3,209 and €1,512 per patient treated at home. The adjusted mean difference was €1,483 (95% confidence interval: €1,181-1,784)., Conclusion: Home treatment of hemodynamically stable patients with acute PE was associated with an estimated net cost reduction of €1,483 per patient. This difference underlines the advantage of triage-based home treatment of these patients., Competing Interests: F.K. reports research grants from Bayer, Bristol-Myers Squibb, Boehringer-Ingelheim, Daiichi-Sankyo, MSD, Actelion, the Dutch Heart Foundation, and the Netherlands Thrombosis Foundation, outside the submitted work. M.H. reports grants from ZonMW Dutch Healthcare Fund, grants and personal fees from Boehringer Ingelheim, grants and personal fees from Pfizer-BMS, grants and personal fees from Bayer Health Care, grants from Aspen, and grants and personal fees from Daiichi-Sankyo, outside the submitted work., (Thieme. All rights reserved.)

Compared with nonpregnant women, pregnancy carries a four- to fivefold higher risk of venous thromboembolism (VTE). Despite increasing use of heparin prophylaxis in identified high-risk patients, pulmonary embolism still is the leading cause of maternal mortality in the western world. However, evidence on optimal use of thromboprophylaxis is scarce. Thrombophilia, the hereditary or acquired tendency to develop VTE, is also thought to be associated with complications in pregnancy, such as recurrent miscarriage and preeclampsia. In this review, the current evidence on optimal thromboprophylaxis in pregnancy is discussed, focusing primarily on VTE prevention strategies but also discussing the potential to prevent recurrent pregnancy complications with heparin in pregnant women with thrombophilia., Competing Interests: The authors declare that they have no conflict of interest., (Thieme. All rights reserved.)

Background: Lack of data on balancing bleeding and thrombosis risk causes uncertainty about restarting anticoagulants after major bleeding. Anticoagulant reversal trials offer prospectively gathered data after major bleeding with well-documented safety events and restarting behavior., Objectives: To examine the relationship of restarting anticoagulation with thrombosis, rebleeding, and death., Methods: This is a posthoc analysis of a prospective factor Xa inhibitor reversal study at 63 centers in North America and Europe. We compared outcomes of restarted patients with those not restarted using landmark and time-dependent Cox proportional hazards models. Outcomes included thrombotic and bleeding events and death and a composite of all three., Results: Of 352 patients enrolled, oral anticoagulation was restarted in 100 (28%) during 30-day follow-up. Thirty-four (9.7%) had thrombotic events, 15 (4.3%) had bleeding events (after day 3), and 49 (14%) died. In the landmark analysis comparing patients restarted within 14 days to those not, restarting was associated with decreased thrombotic events (hazard ratio [HR] = 0.112; 95% confidence interval [CI]: 0.001-0.944; p  = 0.043) and increased rebleeding (HR = 8.39; 95% CI: 1.13-62.29; p  = 0.037). The time-dependent Cox model showed evidence for a reduction in a composite (thrombotic events, bleeding, and death) attempting to capture net benefit (HR = 0.384; 95% CI: 0.161-0.915; p  = 0.031)., Conclusion: This analysis provides modest evidence that restarting anticoagulation in factor Xa inhibitor-associated major bleeding patients is correlated with reduced risk of thrombotic events and increased risk of rebleeding. There is low-level evidence of net benefit for restarting. A randomized trial of restarting would be appropriate., Competing Interests: T.J.M.: CSL Behring: consulting; Portola: grant support, steering committee; Octapharma: steering committee. B.K.: none. P.Y.: Portola: employee. S.M.: Daiichi Sankyo, Bayer, Aspen Pharma: grant support; Bristol Myers Squibb/Pfizer, Boehringer Ingelheim, Portola: advisory board; Portola: lecture fees; AbbVie: adjudication committee. J.B.-W.: Bayer, Daiichi Sankyo: grant support, lecture fees, advisory board fees; Pfizer: grant support; Portola: lecture fees, advisory board fees. J.W.E.: AstraZeneca, Bayer, Boehringer Ingelheim, Bristol Myers Squibb/Pfizer, Daiichi Sankyo, Eli Lilly, GlaxoSmithKline, Janssen, Sanofi-Aventis: grant support, honoraria. M.C.: Bristol Myers Squibb Canada, Asahi Kasei, Servier Canada, Precision Biologics, Hemostasis Reference Laboratory, CSL Behring: advisory board; Alexion, Pfizer, CSL Behring, Diagnostica Stago: educational funding; Bayer, Leo Pharma: grant support; Daiichi Sankyo, Bayer, Octapharma: data safety monitoring board. L.X.: None. P.V.: Bayer Healthcare, Boehringer Ingelheim, Daiichi Sankyo, Pfizer, Bristol Myers Squibb, Leo Pharma: grant support, consulting, lecture fees; Boehringer Ingelheim: adjudication committee; Anthos, Janssen, Portola: consulting. D.M.S.: Bayer, Bristol Myers Squibb/Pfizer, Servier Canada, Novartis, Leo Pharma, Aspen Pharma, Portola: consulting. S.J.C.: Portola, Bristol Myers Squibb, Bayer, Daiichi Sankyo: grant support, consulting; Javelin: consulting., (The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/).)

Historically, the vaccination strategies developed in the second half of the 20th century have facilitated the eradication of infectious diseases. From the onset of COVID-19 pandemic to the end of April 2021, more than 150 million cases and 3 million deaths were documented worldwide with disruption of the economic and social activity, and with devastating material, physical, and psychological consequences. Reports of unusual and severe thrombotic events, including cerebral and splanchnic venous thrombosis and other autoimmune adverse reactions, such as immune thrombocytopenia or thrombotic microangiopathies in connection with some of the SARS-CoV-2 vaccines, have caused a great deal of concern within the population and the medical community. This report is intended to provide practical answers following an overview of our knowledge on these thrombotic events that are extremely rare but have serious consequences. Vaccine hesitancy threatens to reverse the progress made in controlling vaccine-preventable diseases. These adverse events must be put into perspective with an objective analysis of the facts and the issues of the vaccination strategy during this SARS-CoV-2 pandemic. Health care professionals remain the most pertinent advisors and influencers regarding vaccination decisions; they have to be supported to provide reliable and credible information on vaccines. We need to inform, reassure, and support our patients when the prescription is made. Facing these challenges and observations, a panel of experts express their insights and propose a tracking algorithm for vaccinated patients based on a 10-point guideline for decision-making on what to do and not to do., Competing Interests: None declared., (The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/).)

As a result of the successful completion of their respective phase III studies compared with vitamin K antagonists (VKAs), four direct oral anticoagulants (DOACs) have been approved for the treatment and secondary prevention of venous thromboembolism (VTE). These DOACs-apixaban, dabigatran, edoxaban, and rivaroxaban-have subsequently seen a steady uptake among clinicians since their approval. Despite the suitability of DOACs for a broad range of patients, they are not appropriate in certain situations, whereas in others they require additional considerations such as dose reductions. Subanalyses of phase III trials and studies on specific VTE patient populations have been conducted to evaluate the safety and efficacy of the DOACs in a broad range of settings, such as patients with renal impairment, patients with cancer, patients of childbearing potential, patients with multiple comorbidities and pediatric patients. Furthermore, many recent guidance documents from important hematological societies and other specialists have incorporated several of these developments. These documents also identify the patients for whom DOACs are not suitable and where traditional anticoagulation options such as heparins or VKAs should be considered instead. This review provides an overview of key VTE patient subgroups, the clinical evidence supporting the use of anticoagulation in these patients, and a discussion of the most appropriate approaches to their management, including considerations such as dosing, acute and extended treatment durations, and DOAC selection., Competing Interests: C.E.K. reports personal fees from Bayer Health Care, Boehringer Ingelheim, Bristol Myers Squibb, Daiichi Sankyo, and Pfizer Pharma during the conduct of the study; personal fees from Amgen and Sanofi-Aventis outside the submitted work. S.M. reports grants and personal fees from Aspen, Bayer, BMS/Pfizer, Boehringer Ingelheim, Daiichi Sankyo, GSK, Portola, Sanquin, and Sanofi during the conduct of the study., (Georg Thieme Verlag KG Stuttgart · New York.)

Background:  Factor V (FV) is proteolytically activated to FVa, which assembles with FXa in the prothrombinase complex. The C-terminus of tissue factor pathway inhibitor-α (TFPIα) inhibits both the activation and the prothrombinase activity of FV(a), but the pathophysiological relevance of this anticoagulant mechanism is unknown. FV Leiden (FVL) is less susceptible to inhibition by TFPIα, while overexpression of FV splicing variants with increased affinity for TFPIα (FV-short) causes bleeding., Objective:  This study aims to develop a plasma-based assay that quantifies the susceptibility of FV(a) to inhibition by the TFPIα C-terminus., Materials and Methods:  FV in highly diluted plasma was preactivated with FXa in the absence or presence of the TFPIα C-terminal peptide. After adding prothrombin, thrombin formation was monitored continuously with a chromogenic substrate and prothrombinase rates were obtained from parabolic fits of the absorbance tracings. TFPI resistance was expressed as the ratio of the prothrombinase rates with and without peptide (TFPIr)., Results:  The TFPIr (0.25-0.34 in 45 healthy volunteers) was independent of FV levels. The TFPIr increased from normal individuals (0.29, 95% confidence interval [CI] 0.28-0.31) to FVL heterozygotes (0.35, 95% CI 0.34-0.37) and homozygotes (0.39, 95% CI 0.37-0.40), confirming TFPI resistance of FVL. Two individuals overexpressing FV-short Amsterdam had markedly lower TFPIr (0.16, 0.18) than a normal relative (0.29), in line with the high affinity of FV-short for TFPIα., Conclusion:  We have developed and validated an assay that measures the susceptibility of plasma FV to the TFPIα C-terminus. Once automated, this assay may be used to test whether the TFPIr correlates with thrombosis or bleeding risk in population studies., Competing Interests: None declared., (Georg Thieme Verlag KG Stuttgart · New York.)

In the Hokusai VTE Cancer study, edoxaban was non-inferior to dalteparin for the composite outcome of recurrent venous thromboembolism (VTE) and major bleeding in 1,050 patients with cancer-associated VTE. The absolute rate of recurrent VTE was 3.4% lower with edoxaban, whereas the absolute rate of major bleeding was 2.9% higher. The present analysis focuses on the sites, clinical presentation, course and outcome of bleeding events, and the associated tumour types. Major bleeds and their severity (categories 1-4) were blindly adjudicated by a committee using a priori defined criteria, and data were analysed in the safety population. Major bleeding occurred in 32 of 522 patients given edoxaban (median treatment duration, 211 days) and in 16 of 524 patients treated with dalteparin (median treatment duration, 184 days); no patients had more than one major bleed. There were no fatal bleeds with edoxaban, and two with dalteparin. Severe bleeding at presentation (category 3 or 4) occurred in 10 (1.9%) and 11 (2.1%) patients in the edoxaban and dalteparin groups, respectively. The excess of major bleeding with edoxaban was confined to patients with gastrointestinal cancer. However, severe major bleeding at presentation (category 3 or 4) in this sub-group occurred in 5 of 165 (3.0%) and in 3 of 140 (2.1%) patients given edoxaban or dalteparin, respectively.In conclusion, this analysis suggests that while oral edoxaban is an appropriate alternative to subcutaneous dalteparin for treatment of cancer-associated VTE, the use of edoxaban in patients with gastrointestinal cancer requires careful benefit-risk weighting., Competing Interests: N. Kraaijpoel has nothing to disclose. M. Di Nisio reports personal fees from Daiichi Sankyo. F.I. Mulder has nothing to disclose. N. van Es reports personal fees from Daiichi Sankyo and Pfizer. J. Beyer-Westendorf reports grants and personal fees from Bayer AG, Boehringer-Ingelheim, Daiichi Sankyo, Pfizer and Portola. M. Carrier reports grants from BMS and Leo Pharma, and personal fees from Pfizer, Bayer, Sanofi and Leo Pharma. D. Garcia reports grants and personal fees from Daiichi Sankyo, Janssen and Incyte, and personal fees from BMS and Boehringer-Ingelheim. M. Grosso, M.F. Mercuri, G. Zhang and L. Schwocho are employees of Daiichi Sankyo Inc. A.K. Kakkar reports grants and personal fees from Bayer AG, and personal fees from Boehringer-Ingelheim, Janssen Pharma, Sanofi SA and Verseon. S. Middeldorp reports grants and personal fees from GSK, BMS/Pfizer, Aspen and Daiichi Sankyo, and personal fees from Bayer, Boehringer-Ingelheim, and grants from Sanquin. C. Rojas Hernandez reports personal fees from Daiichi Sankyo. A. Santamaria reports personal fees from Bayer AG, Boehringer-Ingelheim, Pfizer, Bristol-Myers Squibb, Daiichi Sankyo, LeoPharma, Sanofi-Aventis, Rovia and SOBI. A. Segers reports grants from Daiichi Sankyo, IONIS Pharmaceuticals and Janssen Pharmaceuticals. P. Verhamme reports grants and personal fees from Bayer Healthcare, LeoPharma, Daiichi Sankyo and Boehringer-Ingelheim, and personal fees from BMS, Portola, Medscape, Medtronic and Pfizer. T.F. Wang has nothing to disclose. J.I. Weitz reports personal fees from Daiichi-Sankyo, Bayer Healthcare, BMS, Boehringer-Ingelheim, Ionis Pharmaceuticals, Janssen, Johnson and Johnson, Pfizer, Portola, Medscape and Novartis. J.I. Zwicker reports grants from Quercegen and Incyte, and personal fees from Daichii Sankyo and Parexel. H.R. Büller reports personal fees from Daiichi Sankyo, Bayer Healthcare, BMS/Pfizer, Boehringer-Ingelheim, Portola, Medscape, Eli Lilly, Sanofi Aventis and Ionis. G.E. Raskob reports personal fees from Daiichi Sankyo, Itreas, Bayer, Boehringer-Ingelheim, Bristol-Myers Squibb, Eli Lilly, Isis Pharmaceuticals, Janssen, Pfizer and Portola., (Georg Thieme Verlag KG Stuttgart · New York.)

Cancer patients with venous thromboembolism (VTE) have a two- to six-fold increased risk of anticoagulant-related major bleeding events compared with VTE patients without cancer. It is unknown whether major bleeding events are more severe in cancer patients than in those without cancer. Individual patient data from four randomized phase III trials that compared factor Xa inhibitors and vitamin K antagonists for the treatment of VTE were used to compare the severity of major bleeding events in patients with and without cancer. Using predefined criteria, the severity of the clinical presentation and course of major bleeding events were classified into four categories of increasing severity. A one-stage meta-analysis was used to evaluate the effect of cancer on the severity of the clinical presentation and course by estimating crude odds ratios (ORs) and ORs adjusted for age, sex and anticoagulant type with 95% confidence intervals (CIs). The study group comprised 290 patients with major bleeding, of whom 50 (17%) had cancer. The clinical presentation was judged to be severe (category 3 or 4) in 38% of patients with cancer and 44% of patients without cancer (adjusted OR, 0.90; 95% CI, 0.47-1.72). The clinical course was found to be severe in 20 and 25% of patients with and without cancer, respectively (adjusted OR, 0.75; 95% CI, 0.35-1.61). The present study suggests that the clinical presentation and course of anticoagulant-related major bleeding events are not more severe in cancer patients than in patients without cancer. This may be reassuring for physicians who treat cancer patients with anticoagulant-related bleeding., Competing Interests: Conflicts of Interest: N. K. has nothing to disclose. N. v. E. reports a personal fee from Pfizer. S. M. B. has nothing to disclose. M. P. A. B. has nothing to disclose. E. S. E. reports personal fees from CSL Behring, grants from Sanquin and grants from Baxter, outside the submitted work. A. T. C. reports grants and personal fees from Bristol-Myers Squibb and Pfizer Limited, and personal fees from Boehringer Ingelheim, Johnson & Johnson, Portola, Sanofi Aventis, XO1, Janssen and Bayer HealthCare, and grants from Daiichi Sankyo, outside the submitted work. S. M. reports grants and personal fees from GSK, BMS/Pfizer, Aspen and Daiichi Sankyo, personal fees from Bayer and Boehringer Ingelheim, and grants from Sanquin, outside the submitted work. G. E. R. reports personal fees from Daiichi Sankyo, Itreas, Bayer, Boehringer Ingelheim, Bristol-Myers Squibb, Eli Lilly, Isis Pharmaceuticals, Janssen, Pfizer and Portola, outside the submitted work. H. R. B. reports grants and personal fees from Daiichi Sankyo, Bayer, Boehringer Ingelheim, Bristol-Myers Squibb, Pfizer, Isis Pharmaceuticals, GSK, Roche, Sanofi and Thrombogenics, outside the submitted work., (Schattauer GmbH Stuttgart.)

Factor Xa (fXa)-inhibitors are as effective and safer than vitamin-K-antagonists (VKA) in the treatment of venous thromboembolism (VTE). We previously classified the severity of clinical presentation and course of all major bleeding events from the EINSTEIN, AMPLIFY and HOKUSAI-VTE trials separately. The current aim was to combine these findings in order to increase precision, assess a class effect and analyse presentation and course for different types of bleeding, i. e. intracranial, gastro-intestinal, and other. We classified the clinical presentation and course of all major bleeding events using pre-defined criteria. Both classifications comprised four categories; one being the mildest, and four the most severe. Odds ratios (OR) were calculated for all events classified as category three or four between fXa-inhibitors and VKA recipients. Also, ORs were computed for different types of bleeding. Major bleeding occurred in 111 fXa-inhibitor recipients and in 187 LMWH/VKA recipients. The clinical presentation was classified as category three or four in 35 % and 48 % of the major bleeds in fXa inhibitor and VKA recipients, respectively (OR 0.59, 95 % CI 0.36-0.97). For intracranial, gastro-intestinal and other bleeding a trend towards a less severe presentation was observed for patients treated with fXa inhibitors. Clinical course was classified as severe in 22 % of the fXa inhibitor and 25 % of the VKA associated bleeds (OR 0.83, 95 % CI 0.47-1.46). In conclusion, FXa inhibitor associated major bleeding events had a significantly less severe presentation and a similar course compared to VKA. This finding was consistent for different types of bleeding.

Factor Xa (fXa)-inhibitors are as effective and safer than vitamin-K-antagonists (VKA) in the treatment of venous thromboembolism (VTE). We previously classified the severity of clinical presentation and course of all major bleeding events from the EINSTEIN, AMPLIFY and HOKUSAI-VTE trials separately. The current aim was to combine these findings in order to increase precision, assess a class effect and analyse presentation and course for different types of bleeding, i. e. intracranial, gastro-intestinal, and other. We classified the clinical presentation and course of all major bleeding events using pre-defined criteria. Both classifications comprised four categories; one being the mildest, and four the most severe. Odds ratios (OR) were calculated for all events classified as category three or four between fXa-inhibitors and VKA recipients. Also, ORs were computed for different types of bleeding. Major bleeding occurred in 111 fXa-inhibitor recipients and in 187 LMWH/VKA recipients. The clinical presentation was classified as category three or four in 35% and 48% of the major bleeds in fXa inhibitor and VKA recipients, respectively (OR 0.59, 95% CI 0.36-0.97). For intracranial, gastro-intestinal and other bleeding a trend towards a less severe presentation was observed for patients treated with fXa inhibitors. Clinical course was classified as severe in 22% of the fXa inhibitor and 25% of the VKA associated bleeds (OR 0.83, 95% CI 0.47-1.46). In conclusion, FXa inhibitor associated major bleeding events had a significantly less severe presentation and a similar course compared to VKA. This finding was consistent for different types of bleeding., Competing Interests: Dr. Bleker has nothing to disclose. Dr. Brekelmans has nothing to disclose. Dr. Eerenberg reports personal fees from CSL Behring, grants from Sanquin, grants from Baxter, outside the submitted work. Dr. Cohen reports grants and personal fees from Bristol-Myers Squibb, Pfizer Limited, and personal fees from Boehringer Ingelheim, Johnson & Johnson, Portola, Sanofi Aventis, XO1, Janssen, Bayer HealthCare and grants from Daiichi Sankyo, outside the submitted work. Dr. Middeldorp reports grants and personal fees from GSK, BMS/Pfizer, Aspen, and Daiichi Sankyo, personal fees from Bayer, Boehringer Ingelheim, and grants from Sanquin, outside the submitted work. Dr. Raskob reports personal fees from Daiichi Sankyo, Itreas, Bayer, Boehringer Ingelheim, Bristol-Myers Squibb, Eli Lilly, Isis Pharmaceuticals, Janssen, Pfizer and Portola, outside the submitted work. Dr. Buller reports grants and personal fees from Daiichi Sankyo, Bayer, Boehringer Ingelheim, Bristol-Myers Squibb, Pfizer, Isis Pharmaceuticals, GSK, Roche, Sanofi, Thrombogenics, outside the submitted work., (Schattauer GmbH.)

Competing Interests: Disclosure The authors report no conflicts of interest in this work.

Abnormal vaginal bleeding can complicate direct oral anticoagulant (DOAC) treatment. We aimed to investigate the characteristics of abnormal vaginal bleeding in patients with venous thromboembolism (VTE) receiving apixaban or enoxaparin/warfarin. Data were derived from the AMPLIFY trial. We compared the incidence of abnormal vaginal bleeding between patients in both treatment arms and collected information on clinical presentation, diagnostic procedures, management and outcomes. In the AMPLIFY trial, 1122 women were treated with apixaban and 1106 received enoxaparin/warfarin. A clinically relevant non-major (CRNM) vaginal bleeding occurred in 28 (2.5 %) apixaban and 24 (2.1 %) enoxaparin/warfarin recipients (odds ratio [OR] 1.2, 95 % confidence interval [CI] 0.7-2.0). Of all CRNM bleeds, 28 of 62 (45 %) and 24 of 120 (20 %) were of vaginal origin in the apixaban and enoxaparin/warfarin group, respectively (OR 3.4; 95 % CI 1.8-6.7). Premenopausal vaginal bleeds on apixaban were characterised by more prolonged bleeding (OR 2.3; 95 %CI 0.5-11). In both pre- and postmenopausal vaginal bleeds, diagnostic tests were performed in six (21 %) and in seven (29 %) apixaban and enoxaparin/warfarin treated patients, respectively. Medical treatment was deemed not necessary in 16 (57 %) apixaban and 16 (67 %) enoxaparin/warfarin recipients. The severity of clinical presentation and course of the bleeds was mild in 75 % of the cases in both groups. In conclusion, although the absolute number of vaginal bleeding events is comparable between apixaban and enoxaparin/warfarin recipients, the relative occurrence of vaginal bleeds is higher in apixaban-treated women. The characteristics and severity of bleeding episodes were comparable in both treatment arms.

Apixaban, a direct acting oral anticoagulant (DOAC), was found to be non-inferior to and safer as enoxaparin followed by warfarin for treatment of venous thromboembolism (VTE) in the AMPLIFY trial. Information is needed on how bleeding events with DOACs present and develop. In this post-hoc analysis, the clinical presentation and course of all major and clinically relevant non major (CRNM) bleeding events in the AMPLIFY trial were blindly classified by three investigators, using pre-designed classification schemes containing four categories. Odds ratios (OR) for classifying as category three or four (representing a more severe clinical presentation and course) were calculated between apixaban and enoxaparin/warfarin. In total, 63 major and 311 CRNM bleeding events were classified. Of the major bleeds, a more severe clinical presentation occurred in 28.5 % of apixaban versus 44.9 % of enoxaparin/warfarin related recipients (OR 0.49, 95 % confidence interval [CI] 0.14-1.78). A severe clinical course was observed in 14.3 % and in 12.2 %, respectively (OR 1.19, 95 %CI 0.21-6.69). Of the CRNM bleeding events, a more severe clinical presentation and extent of clinical care was found in 25 % of apixaban recipients compared to 22.7 % in the enoxaparin/warfarin group (OR 1.13, 95 %CI 0.65-1.97). The clinical presentation and course of major and CRNM bleeds were similar in apixaban and enoxaparin/warfarin treated patients. This finding should reassure physicians and patients that even in the absence of a specific reversal agent, apixaban is a convenient and safe choice for VTE.

Direct oral anticoagulants (DOACs) provide an effective, safe, and convenient therapeutic alternative to warfarin and other vitamin K antagonists (VKAs), and are now established for a wide range of indications. The use of DOACs in women merits special consideration due to two main situations: first, in relation to fertility, pregnancy, and lactation in women of reproductive age; second, because of their bleeding risk, leading to abnormal uterine and/or other genital tract bleeding. This review focuses on these two clinical situations, including approaches to management in the context of available information., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Today, direct oral anticoagulants (DOAC) are widely used alternatives to Vitamin-K antagonists (VKA). Women of reproductive age may become pregnant during anticoagulation and, while VKA carry an embryotoxic potential, the risk of DOAC embryopathy is unknown. As a result, some patients elect to terminate pregnancy for fear of DOAC embryotoxicity. To assess the risk of DOAC embryopathy, we reviewed cases of DOAC exposure in pregnancy collected from physicians, literature and pharmacovigilance systems of drug authorities and manufacturers. A total of 357 reports including duplicates were available from which 233 unique cases could be identified. Information on pregnancy outcome was available in only 137/233 cases (58.8 %): 67 live births (48.9 %); 31 miscarriages (22.6 %); 39 elective pregnancy terminations (28.5 %). In 93 cases (39.9 %) no outcome data were available (including 3 cases of ongoing pregnancy). Of the 137 pregnancies with reported outcomes, seven showed abnormalities (5.1 %) of which three (2.2 %) could potentially be interpreted as embryopathy: live birth with facial dysmorphism; miscarriage in week 10 with limb abnormality; elective pregnancy termination due to a foetal cardiac defect in a woman who had to terminate a previous pregnancy due to Fallot tetralogy. Within its limitations (small numbers, incomplete outcome data) our results do not indicate that DOAC exposure in pregnancy carries a high risk of embryopathy or that DOAC exposure per se should be used to direct patient counselling towards pregnancy termination. Pregnancy outcome data are inconsistently captured in pharmacovigilance databases indicating the strong need for a more robust system of reporting.

Post-thrombotic syndrome (PTS) is a common complication of deep-vein thrombosis (DVT). Poor quality treatment with vitamin K antagonists (VKA) is a risk factor for PTS. We hypothesised that treatment with the direct oral anticoagulant (DOAC) rivaroxaban may lower PTS incidence as compared to enoxaparin/VKA, as DOACs have a more stable pharmacologic profile than VKA. We performed a post-hoc subgroup analysis of the Einstein DVT trial (n=3449). Kaplan-Meier survival analysis was performed to compare the cumulative incidence of PTS between the rivaroxaban and enoxaparin/VKA groups. Hazard ratios (HR) and 95 % confidence intervals (CI) were calculated using Cox proportional hazards models. We included 336 patients with a mean age of 58 ± 16 years and a median follow-up after index DVT of 57 months (interquartile range 48-64). Of these, 162 (48 %) had been treated with rivaroxaban and 174 (52 %) with enoxaparin/VKA. The cumulative PTS incidence at 60 months follow-up was 29 % in the rivaroxaban group and 40 % in the enoxaparin/VKA group. After adjusting for age, gender, body mass index, previous VTE, ipsilateral recurrent DVT, extent of DVT, idiopathic DVT, duration of anticoagulant treatment, compliance to assigned study medication, elastic compression stocking use and active malignancy, the HR of PTS development for rivaroxaban was 0.76 (95 % CI: 0.51-1.13). In conclusion, treatment of acute DVT with rivaroxaban was associated with a numerically lower but statistically non-significant risk of PTS compared to enoxaparin/VKA treatment. The potential effect on reducing PTS deserves evaluation in a large randomised trial.

Cerebral venous thrombosis (CVT) is a rare thrombotic disorder involving the cerebral veins and dural sinuses. In contrast to more common sites of venous thromboembolism (VTE), such as the legs and lungs, CVT mainly affects young adults and children, and women are affected three times more often than men. Although presenting symptoms are variable, headache is usually the first symptom, often in combination with focal neurologic deficits and epileptic seizures. The primary therapy for CVT consists of heparin followed by oral anticoagulation for at least 3 to 6 months. The mortality in the acute phase is 5 to 10% and a substantial proportion of survivors suffer from long-term disabilities. A large number of risk factors have been linked to CVT, although the scientific evidence for an association varies considerably between risk factors. Some risk factors, such as hereditary thrombophilia, correspond with risk factors for more common sites of VTE, whereas others, such as head trauma, are specific to CVT. In most patients, at least one risk factor can be identified. In this review, we provide an overview of the risk factors for CVT., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Edoxaban is a once-daily direct oral anticoagulant (DOAC). The Hokusai-VTE study revealed that, after initial treatment with heparin, edoxaban was non-inferior to and safer than vitamin K antagonists (VKA) in the prevention of recurrent deep-vein thrombosis and pulmonary embolism. This is the first report on the clinical relevance and management of bleeding events with edoxaban. All major bleeding events were classified blindly by three study-independent adjudicators. Pre-defined criteria were used to classify severity of clinical presentation and, separately, the clinical course and outcome into four categories. Major bleeding occurred in 56 patients treated with edoxaban and 65 patients treated with VKA. The severest categories (3 or 4) of the clinical presentation were assigned to 46 % of the major bleeding episodes in edoxaban recipients versus 58 % of the major bleeds in VKA recipients (odds ratio [OR] 0.62, 95 % confidence interval [CI] 0.30-1.27, p = 0.19). Clinical course was classified as severe (category 3 or 4) in 23 % of the edoxaban and 29 % of the VKA associated bleeds (OR 0.73, 95 % CI 0.32-1.66, p = 0.46). In conclusion, edoxaban associated major bleeding events have a comparable clinical presentation and course to major bleeds with VKA in patients treated for venous thromboembolism in the Hokusai-VTE study. These results may assure physicians that it is safe to prescribe this medication. If a major bleeding during edoxaban treatment occurs, its clinical presentation and clinical course are not worse than in VKA-treated patients.

The use of low-dose aspirin and heparinoids has improved the pregnancy outcome in obstetric antiphospholipid syndrome (APS). However, current treatment fails in 20-30% of APS pregnancies, raising the need to explore other treatments to improve obstetrical outcome. Hydroxychloroquine (HCQ) is widely used in patients with autoimmune diseases, mainly systemic lupus erythematous (SLE), due to its anti-inflammatory, anti-aggregant and immune-regulatory properties. Evidence from in vitro and animal models suggests a potential protective effect of HCQ in obstetric APS. Pending the availability of prospective trials, we aimed to systematically review the available evidence and to assess the clinical judgment of a panel of experts regarding the use of HCQ in improving pregnancy outcome in women with antiphospholipid antibodies (aPL). Clinical data on the ability of HCQ to improve pregnancy outcome in women with aPL are very limited in the available literature. Only one cohort study evaluating maternal and fetal outcome of pregnancy in patients with SLE who were exposed to HCQ was identified. Four of 14 (29%) treated with HCQ patients had pregnancy failure, compared with six of 24 (25%) of patients not treated with HCQ. However, the effect of HCQ was not adjusted for the use of other medications such as aspirin, heparins or steroids. Selected experts were contacted by e-mail and asked to review the summary of the evidence provided by the working group and to briefly answer each of the proposed questions. Overall, the panel of experts agreed that adding HCQ could be considered in selected cases or after failure of standard treatment with aspirin and a heparin agent. Specifically, the majority of experts considered adding HCQ in specific scenarios, such as women with previous thrombosis (either arterial and/or venous), and/or with previous ischaemic placenta-mediated complications. Prospective studies are necessary before the use of HCQ during pregnancy in women with aPL should be routinely recommended for clinical practice.

Despite knowledge of various inherited risk factors associated with venous thromboembolism (VTE), no definite cause can be found in about 50% of patients. The application of data-driven searches such as GWAS has not been able to identify genetic variants with implications for clinical care, and unexplained heritability remains. In the past years, the development of several so-called next generation sequencing (NGS) platforms is offering the possibility of generating fast, inexpensive and accurate genomic information. However, so far their application to VTE has been very limited. Here we review basic concepts of NGS data analysis and explore the application of NGS technology to VTE. We provide both computational and biological viewpoints to discuss potentials and challenges of NGS-based studies.

Cerebral venous thrombosis (CVT) is a rare manifestation of venous thromboembolism (VTE) and stroke. The aim of our systematic review was to provide an updated summary of the strength of association between CVT and thrombophilia and to explore the relevance of thrombophilia for recurrence of CVT or other VTE, or other outcome variables. MEDLINE (via PubMed), EMBASE (via Ovid), and CENTRAL were systematically searched, including references of retrieved articles. Cohort studies of ≥ 40 patients and case-control studies comparing the prevalence of thrombophilia in patients with CVT and unrelated controls were eligible. Two reviewers independently selected studies, assessed quality, and extracted data. A meta-analysis was performed for high quality case-control studies with unselected cases and healthy controls. Odds ratios with 95% confidence intervals were calculated and pooled. We included 23 cohort studies and 33 case-control studies. A significant association was demonstrated between CVT and all inherited thrombophilic factors, as well as increased levels of homocysteine. Inconclusive results were found on the relevance of thrombophilia for recurrent CVT or other VTE. Although there is a strong association between CVT and thrombophilia, the clinical relevance of thrombophilia testing in patients with CVT seems limited, similarly to other forms of VTE., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Venous thromboembolism (VTE) is a common complication in all types of cancer and adversely impacts cancer prognosis. Randomized controlled trials with primary thromboprophylaxis in cancer patients generally show effective VTE relative risk reductions of up to 60%. However, absolute risks of VTE were fairly low. Thromboprophylaxis should therefore only be recommended to cancer patients at highest risk of VTE, who may benefit most from prophylaxis. Predictive risk models to identify patients at a high risk of VTE are promising, however additional validation is required. An increasing proportion of cancer-associated VTE is formed by incidental VTE, with similar risk factors and clinical consequences. Randomized trials are not yet available, but it seems reasonable to treat incidental VTE similarly to symptomatic VTE. In a substantial proportion of patients with unprovoked VTE without known cancer at the time of VTE diagnosis, concomitant or occult cancer is identified. Studies have investigated the value of extensive screening over routine examinations alone for occult cancer. Although extensive screening may be able to identify more occult cancers, its clinical benefit over routine screening has not been demonstrated., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Factor V Leiden is a procoagulant mutation associated with venous and arterial thrombosis and pregnancy complications. Its high prevalence of 5% in Caucasians suggests that there are evolutionary benefits as well. Carriers are indeed reported to have various advantageous phenotypes related to haemostasis, inflammation and fertility: less acute blood loss; less menstrual blood loss; decreased risk of intracranial haemorrhage; milder phenotypes of haemophilia; higher survival in and lower susceptibility to severe sepsis; higher survival in acute respiratory distress syndrome; less severe diabetic nephropathy and higher fecundity in both men and women. Not all these associations come from high quality adequately powered studies and many have not been confirmed by further research. The evolutionary influence of the alleged associations varies and is difficult to establish, partly due to a shift over time in risk factors of the diseases concerned. For most of the phenotypes possible mechanistic explanations can be provided. The procoagulant phenotype and perhaps also certain pregnancy complications follow from activated protein C (APC) resistance. Elevated APC levels possibly mediate anti-inflammatory effects. Higher sperm counts and more successful embryo implantation seem to play a role in the increased fecundity.

Pregnancy and the postpartum period are associated with an increased risk of venous thromboembolism (VTE), which complicates 1 to 2 of 1,000 pregnancies and represents a leading cause of mortality during pregnancy in developed countries. Strong evidence for the management of pregnancy-related VTE is missing, mostly because pregnant women have been excluded from all major trials investigating different diagnostic tools and treatment regimens. Nevertheless, proper evaluation of the involved risk factors is mandatory to reduce the incidence of pregnancy-related VTE and improve outcomes. Low-molecular-weight heparins are considered as a first-line option in the management of pregnancy-related VTE. With regard to future research, there is a need for methodologically strong studies in pregnant women, especially with respect to risk stratification, optimal heparin doses, usefulness of anti-FXa levels and their correlation with clinical outcomes, and correct management of anticoagulation during delivery., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Treatment of acute lymphoblastic leukaemia (ALL) is frequently complicated by venous thromboembolism (VTE). The efficacy and optimal approach of VTE prevention are unclear, particularly in adult patients. We assessed the effect of thromboprophylaxis on symptomatic VTE incidence in cycle 1 of ALL treatment in adult patients. Secondly, we explored potential etiologic factors for VTE and the clinical impact of VTE on ALL outcome. We retrospectively assessed symptomatic VTE incidence and use of thromboprophylaxis in 240 adults treated for newly diagnosed ALL in the Dutch-Belgian HOVON-37 multicentre study (1999-2005). Potential etiologic factors were explored by analysis of patient and disease characteristics, impact of VTE on ALL outcome by analysis of complete remission and overall survival rates. Symptomatic VTE was observed in 24 of 240 patients (10%). Thromboprophylaxis differed by centre (prophylactic fresh frozen plasma (FFP) supplementation or no thromboprophylaxis) and was applied only during L-asparaginase in cycle 1. VTE incidence was significantly lower with FFP supplementation than without FFP (6% vs. 19%; adjusted odds ratio [OR] 0.28; 95% confidence interval [CI] 0.10-0.73). FFP did not influence antithrombin or fibrinogen plasma levels. Patients with VTE in cycle 1 had a significantly poorer complete remission rate (adjusted OR 0.18; 95% CI 0.07-0.50), particularly patients with cerebral venous thrombosis (adjusted OR 0.17; 95% CI 0.04-0.65). Our study suggests that prophylactic FFP supplementation effectively reduces symptomatic VTE incidence during ALL treatment in adults. This should be confirmed in a randomised controlled trial.

Inherited thrombophilia is defined as a genetically determined tendency to develop venous thromboembolism. In children, inherited thrombophilia contributes to the development of pediatric thromboembolic disease. As a consequence, pediatric hematologists are increasingly requested to test thrombophilia in pediatric patients with thrombosis or asymptomatic children from thrombophilic families. This article reviews the benefits and limitations of testing for thrombophilic disorders, for example, factor V Leiden, prothrombin mutation, and deficiencies of antithrombin, protein C, or protein S in childhood., (© Thieme Medical Publishers.)

Despite knowledge of various inherited risk factors associated with venous thromboembolism (VTE), no definite cause can be found in about 50% of patients. The lack of an intermediate phenotype in VTE impedes the discovery of new familial risk factors. We set out to define an intermediate phenotype for VTE by performing global coagulation analyses in unexplained thrombophilic families. Families were selected through a proband with VTE but without one of the known thrombophilic defects and at least one 1st or two 2nd degree family members with VTE. Clinical data were collected using a standardized questionnaire. Blood samples were collected for overall haemostasis assays (i.e. thrombin generation time [TGT], endogenous thrombin potential [ETP], prothrombin fragment 1+2 [F1+2] and activated protein C-sensitivity ratio [APC-sr] and clot lysis time [CLT]). Data were analysed using logistic regression. Coagulation assays were performed in 353 individuals of whom 41 (12%) had a history of VTE; these belonged to 17 thrombophilic families. Of the tested variables only the ETP was associated with VTE (odds ratio [OR] 1.03 for each % increase, 95% confidence interval [CI] 1.01-1.05). However, the relatively low number of cases does not firmly exclude the other assays as candidate intermediate phenotypes for venous thrombosis. We found that an increased ETP may serve as an intermediate phenotype for VTE and may be used to discover novel inherited risk factors by genetic linkage analysis.

High levels of thrombin-activatable fibrinolysis inhibitor (TAFI) are a supposed risk factor for thrombosis. However, results from previous studies are conflicting. We assessed the absolute risk of venous and arterial thromboembolism in subjects with high TAFI levels (>126 U/dl) versus subjects with normal levels, and the contribution of other concomitant thrombophilic defects. Relatives from four identical cohort studies in families with either deficiencies of antithrombin, protein C or protein S, prothrombin 20210A, high factor VIII levels, or hyperhomocysteinemia were pooled. Probands were excluded. Of 1,940 relatives, 187 had high TAFI levels. Annual incidences of venous thromboembolism were 0.23% in relatives with high TAFI levels versus 0.26% in relatives with normal TAFI levels (adjusted relative risk [RR] 0.8; 95% confidence interval [CI], 0.5-1.3). For arterial thrombosis these were 0.31% versus 0.23% (adjusted RR 1.4; 95% CI, 0.9-2.2). High levels of factor VIII, IX and XI were observed more frequently in relatives with high TAFI levels. Only high factor VIII levels were associated with an increased risk of venous and arterial thrombosis, independently of TAFI levels. None of these concomitant defects showed interaction with high TAFI levels. High TAFI levels were not associated with an increased risk of venous and arterial thromboembolism in thrombophilic families.

Elevated levels of factor VIII:c (elevated FVIII:c) are associated with an increased risk for venous thromboembolism (VTE) and arterial vascular events, and are at least in part determined genetically. We prospectively followed 192 asymptomatic individuals with elevated FVIII:c (>150%) and 340 with normal levels for an average duration of 31 months (range 7 to 56 months) to investigate the risk of VTE and arterial vascular events. Participants were first degree relatives of consecutive patients with elevated FVIII:c and VTE or arterial vascular events before the age of 50 years. The incidences of VTE were 1.25% (0.46-2.73) per year in the subjects with elevated FVIII:c, versus 0.23% (0.03-0.82) in those with normal levels (OR 5.5 [1.1-27.3]). The annual incidences of arterial vascular events were 1.04% (0.34-2.42) and 0.23% (0.03-0.82) in relatives with and without elevated levels of FVIII:c, respectively (OR: 4.5 [0.9-23.5]). After adjustment for age, smoking, known diabetes mellitus, hyperlipidemia, and hypertension, the odds ratio for any event was 3.7 (1.1-13.1). In conclusion, asymptomatic individuals with elevated FVIII:c levels and a positive family history of VTE or arterial vascular events before the age of 50 appear to have a high annual incidence of first VTE and arterial vascular events. Elevated FVIII:c may be a common risk factor for both clinical entities.

In the last decades, the knowledge on the etiology of venous thromboembolism (VTE) has increased tremendously. In approximately half of patients presenting with VTE, one or more thrombophilic defects can be identified. This has led to widespread testing for thrombophilia, despite the fact that, at present, it is unclear whether this should have therapeutic consequences. Here we review the currently established hereditary and acquired thrombophilic defects, and focus on the pros and cons of testing in the setting of VTE. Thrombophilia is defined as a disorder associated with an increased tendency to venous thromboembolism (VTE). Thrombophilia can be acquired, such as in patients with cancer, or congenital, in which case a defect in the coagulation system is hereditary. Egeberg was the first to use the term thrombophilia in 1965, when he described a Norwegian family that had a remarkable tendency to VTE, based on a deficiency of antithrombin. Since then, various laboratory abnormalities, both hereditary and acquired, have been discovered that increase the risk of VTE. This article reviews the currently established thrombophilic abnormalities and discusses the potential usefulness and implications of testing for thrombophilia.

As homocysteine-lowering treatment has not reduced the risk of recurrent thrombosis in recent clinical trials, we hypothesized that mild hyperhomocysteinaemia is an epiphenomenon or associated with a low absolute risk of thrombosis. In this retrospective study, we enrolled 478 evaluable first-degree relatives of consecutive patients with venous thrombosis or premature atherosclerosis, and hyperhomocysteinemia. Absolute risks of thrombosis and effects of concomitant thrombophilic defects were compared. Relative risks were adjusted for clustering in families, age, sex, and atherosclerotic risk factors, where appropriate. Annual incidence of venous thrombosis was 0.16% (95% confidence interval [CI], 0.08-0.30) in hyperhomocysteinemic relatives versus 0.11% (CI, 0.05-0.20) in normohomocysteinemic relatives; adjusted relative risk 1.6 (CI, 0.6-4.5). Annual incidences of arterial thrombosis were 0.34% (CI, 0.21-0.52) and 0.24% (CI, 0.15-0.37) in hyperhomocysteinemic and normohomocysteinemic relatives, respectively; adjusted relative risk 1.5 (CI, 0.6-3.5). Concomitance of multiple thrombophilic risk factors increased the risk of venous thrombosis in hyperhomocysteinemic relatives 20 fold, but a comparable effect was demonstrated in normohomocysteinemic relatives. We conclude that hyperhomocysteinaemia is associated with a low absolute risk of venous and arterial thrombosis. Concomitant thrombophilic defects are probably main determinants on the risk of venous thrombosis, rather than hyperhomocysteinaemia itself.

Determining the optimal duration of vitamin K antagonist (VKA) therapy for patients with venous thromboembolism (VTE) requires a weighting of the benefits and risks of treatment. The objectives of our study were to investigate patient variability in health state valuations associated with VKA therapy and treatment preferences, and to investigate the extent to which valuations and treatment preferences are associated with prior experience with these health states and other patient characteristics. Valuations of outcomes after VTE scaled from 0 (tantamount to death) to 1 (tantamount to perfect health) were elicited from 53 patients who had experienced VTE, 23 patients who had experienced major bleeding during treatment, and 48 patients with the post-thrombotic syndrome. In addition, patients' treatment preferences were evaluated using treatment trade-off questions. Median health state valuations ranged from 0.33 for 'non-fatal haemorrhagic stroke' to 0.96 for 'no VKA treatment'. Variability between patients was substantial. Patients' treatment preferences also varied: 25% of patients chose cessation of treatment, regardless of the probability of recurrent VTE presented, whereas 23% of patients were never willing to choose cessation of treatment. Differences in valuations and treatment preferences were not associated with type of event experienced. Due to the substantial and unpredictable variability in valuations and treatment preferences, recommendations regarding treatment duration should be tailored to patients' specific values and concerns.

Acquired and hereditary thrombophilias are associated with obstetric complications such as (pre-)eclampsia, HELLP syndrome and fetal loss. Our objective was to assess the risk of obstetric complications in women with elevated levels of FVIII:C or hyperhomocysteinemia, as compared with their relatives who had normal FVIII:C or homocysteine levels. From a large family study of patients with venous thromboembolism or premature atherosclerosis and elevated levels of FVIII:C or hyperhomocysteinemia (propositi), the obstetric histories of female first degree relatives, who had been pregnant at least once, were studied. Levels of FVIII:C and homocysteine (both fasting and post-methionine loading) were determined. The number of obstetric complications was calculated and compared in women with normal and elevated levels of FVIII:C, and normal and elevated levels of homocysteine. Women with elevated levels of FVIII:C had a 15.4% risk for toxicosis, preeclampsia, or HELLP syndrome and a 23.9% for fetal loss. This was not statistically different from women with normal levels of FVIII:C. Women with hyperhomocysteinemia tended to have a lower risk for toxicosis, pre-eclampsia, or HELLP syndrome (8.0%, RR 0.6, 95% CI 0.2-1.7) and fetal loss (22.0%, RR 0.8, 95% CI 0.5-1.5) as compared to relatives with normal levels, although these differences did not reach statistical significance. If the analysis was limited to comparing extremes, the results did not materially differ. Unselected women with elevated plasma levels of FVIII:C or hyperhomocysteinemia are not at increased risk for obstetric complications as compared to their relatives with normal levels.

The use of oral contraceptives (OC) causes disturbances of the procoagulant, anticoagulant and fibrinolytic pathways of blood coagulation which may contribute to the increased risk of venous thrombosis associated with OC therapy. Here we report the results of a cycle-controlled randomized cross-over study, in which we determined the effects of so-called second and third generation OC's on a number of anticoagulant parameters. In this study, 28 non-OC using women were randomly prescribed either a second generation (150 microg levonorgestrel/30 microg ethinylestradiol) or a third generation OC (150 microg desogestrel/30 microg ethinylestradiol) and who switched to the other OC after a two month wash out period. The anticoagulant parameters determined were: antithrombin (AT), alpha2-macroglobulin (alpha2-M), alpha1-antitrypsin, protein C inhibitor (PCI), protein C, total and free protein S and activated protein C sensitivity ratios (APC-sr) measured with two functional APC resistance tests which quantify the effect of APC on either the activated partial thromboplastin time (aPTT) or on the endogenous thrombin potential (ETP). During the use of desogestrel-containing OC the plasma levels of alpha2-M, alpha1-antitrypsin, PCI and protein C significantly increased, whereas AT and protein S significantly decreased. Similar trends were observed with levonorgestrel-containing OC, although on this kind of OC the changes in AT, PCI and protein S (which was even slightly increased) did not reach significance. Compared with levonorgestrel, desogestrel-containing OC caused a significant decrease of total (p <0.005) as well as free protein S (p <0.0001) and more pronounced APC resistance in both the aPTT (p = 0.02) and ETP-based (p <0.0001) APC resistance tests. These observations indicate that the activity of the anticoagulant pathways in plasma from users of desogestrel-containing OC is more extensively impaired than in plasma from users of levonorgestrel-containing OC.

The effect of oral contraceptives (OC) on fibrinolytic parameters was investigated in a cycle-controlled cross-over study in which 28 non-OC using women were randomly prescribed either a representative of the so-called second (30 microg ethinylestradiol, 150 microg levonorgestrel) or third generation OC (30 microg ethinylestradiol, 150 microg desogestrel) and who switched OC after a two month wash out period. During the use of OC, the levels of tissue-type plasminogen activator (tPA) activity, plasminogen, plasmin-alpha2-antiplasmin complexes and D-dimer significantly increased (by 30 to 80%), while the levels of plasminogen activator inhibitor- (PAI-1) antigen, PAI-1 activity and tPA antigen significantly decreased (25 to 50%), suggesting an increase in endogenous fibrinolytic activity. These OC-induced changes were not different between the two contraceptive pills. TAFI (thrombin-activatable fibrinolysis inhibitor) levels increased on levonorgestrel, and even further increased on desogestrel. A clot lysis assay that probes both fibrinolytic activity and the efficacy of the coagulation system to generate thrombin necessary to down regulate fibrinolysis via TAFI showed no change of the clot lysis time during OC use. This finding suggests that the OC-induced increase in endogenous fibrinolytic activity is counteracted by an increased capacity of the coagulation system to down regulate fibrinolysis via TAFI. Indeed we observed that during OC use there was a significant increase of F1+2 generation during clot formation. When these assays were performed in the presence of an antibody against factor XI, we observed that the clot lysis time was significantly increased during OC use and that the increase in F1+2 generation during OC therapy was due to a factor XI-independent process, which was significantly higher on desogestrel than on levonorgestrel. These data indicate that the OC-induced inhibition of endogenous fibrinolysis takes place in a factor XI-independent way and is more pronounced on desogestrel than on levonorgestrel-containing OC.

Combined oral contraceptives (OC) are known to increase the risk of venous thromboembolism. The aim of this randomized, cycle-controlled, cross-over study in 28 healthy volunteers was to assess potential differences between the effects of an OC containing 150 microg levonorgestrel (as representative of the so-called second generation OC) and an OC containing 150 microg desogestrel (as representative of the third generation OC) in combination with 30 microg ethinylestradiol on several coagulation factors and markers of thrombin formation. All participants used each OC for two cycles, and were switched to the other OC after a washout period of two menstrual cycles. The plasma concentrations of factors II, VII, X, and fibrinogen significantly increased during use of both the levonorgestrel- and desogestrel-containing OC's. The plasma concentrations of factor VIII increased, and of factor V decreased, changes which only reached statistical significance during the use of the desogestrel-containing OC. During exposure to the desogestrel-containing OC, as compared with the levonorgestrel-containing OC, both factor VII and factor II showed a greater increase (FVII: 32% and 12% respectively; p <0.0001; FII: 16% and 12% respectively; p = 0.048), whereas factor V showed a greater decrease (-11% and -3% respectively; p = 0.010). Only one of the markers for ongoing coagulation (prothrombin fragment 1+2) showed a significant increase during OC use, whereas concentrations of thrombin-antithrombin complexes and soluble fibrin remained unchanged. For these markers, there was no difference between the tested OC's. We conclude that there are differences between the effects of levonorgestrel and desogestrel-containing OC's on some coagulation factors. Whether these changes provide a biological explanation for the reported differences in venous thromboembolic risk is as yet unclear. The real challenge now becomes to define a pattern of changes in the various systems which, if affected simultaneously, may tip the hemostatic balance towards a prethrombotic state and may lead to overt clinical venous thromboembolism.

Resistance to activated protein C (APC), which is almost exclusively caused by a point mutation in the factor V gene (FV:Q506 mutation or FV Leiden) is a recently discovered, prevalent risk factor for the occurrence of venous thromboembolism. It is unknown whether relatives of known patients with this mutation should be screened for the presence of the mutation and what the consequences for asymptomatic carriers would be. This paper addresses the possible benefits and disadvantages of family screening of patients with venous thromboembolism who carry the mutation. Possible prophylactic strategies are discussed and weighed on the basis of estimated incidence rates of venous thromboembolism that are deduced from known relative risks and available population studies.