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On May 26th 2017 the European Parliament and the Council of The European Union adopted the new regulation on in vitro diagnostic medical devices (IVDR)-Regulation EU 2017/746-planned to be applied from May 26th 2022 in substitution to the previous IVD directives (IVDD 98/79 EC). After several health and legal causes due to medical device malfunctions, the European Union (EU) extensively reviewed the previous regulatory, which had remained unchanged since 1998. Aim of the work is to analyse the effects of the new IVDR on the field of haemostasis and thrombosis testing with particular attention to specific clinical conditions. Clinical laboratories will mainly deal with three different situations: (1) Diagnostic test performed with IVDR products used according with clinical indication certified by manufacturers. (2) Diagnostic test performed with certified IVDR products without clinical validation. (3) Diagnostic test performed with reagents classified as Research Use Only (RUO). At present, only few clinical laboratories through different European countries have been prepared to the new IVDR, while many laboratories are not yet aware about crucial aspects of the new process that deeply involves laboratory medicine. In conclusion, each laboratory should be aware of the IVDR certification of the reagents/instruments used in its laboratory. There are several urgent needs regarding IVDR certification: studies about the clinical performance of haemostasis tests, guidelines for LDTs (definition and documentation), internal and external quality controls for the tests recommended/suggested in the guidance/guidelines and finally implementation and/or update of clinical and laboratory guidelines.

Phosphomannomutase 2 (PMM2) deficiency is the most prevalent congenital disorder of glycosylation. It is associated with coagulopathy, including protein C deficiency. Since all components of the anticoagulant and cytoprotective protein C system are glycosylated, we sought to investigate the impact of an N-glycosylation deficiency on this system as a whole. To this end, we developed a PMM2 knockdown model in the brain endothelial cell line hCMEC/D3. The resulting PMM2low cells were less able to generate activated protein C (APC), due to lower surface expression of thrombomodulin and endothelial protein C receptor. The low protein levels were due to downregulated transcription of the corresponding genes (THBD and PROCR, respectively), which itself was related to downregulation of transcription regulators Krüppel-like factors 2 and 4 and forkhead box C2. PMM2 knockdown was also associated with impaired integrity of the endothelial cell monolayer—partly due to an alteration in the structure of VE-cadherin in adherens junctions. The expression of protease-activated receptor 1 (involved in the cytoprotective effects of APC on the endothelium) was not affected by PMM2 knockdown. Thrombin stimulation induced hyperpermeability in PMM2low cells. However, pretreatment of cells with APC before thrombin simulation was still associated with a barrier-protecting effect. Taken as a whole, our results show that the partial loss of PMM2 in hCMEC/D3 cells is associated with impaired activation of protein C and a relative increase in barrier permeability.

The activated clotting time (ACT) is a useful marker of unfractionated heparin (UFH) activity during cardiopulmonary bypass (CPB) or cardiac catheterization. Emicizumab, recently approved for bleeding prevention in haemophilia A patients, acts like FVIII but does not need prior activation; it therefore shortens coagulation times in assays using intrinsic pathway activators and so is expected to shorten the ACT.To evaluated emicizumab's impact on heparin-induced ACT (Hemochron®) prolongation.We measured the high-range (HR) ACT in citrated blood samples from healthy donors (HDs) (n = 9), CPB patients (n = 3) and emicizumab-treated patients (n = 5) after spiking with UFH and/or emicizumab. The low range (LR) ACT was also measured in spiked-samples from HDs and emicizumab-treated patients.In HDs, the median [interquartile range] baseline HR-ACTs were similar with and without emicizumab (129 [123-138] and 136 [115-141] s for 50 μg/ml, respectively); whatever the concentration of emicizumab (10 to 50 μg/ml), increasing the UFH concentration (1-5 UI/ml) prolonged the HR-ACT. In blood from patients undergoing CPB, the HR-ACT prolongation observed during this procedure was not masked by emicizumab at any concentration. Likewise, the addition of increasing concentrations of UFH to blood from emicizumab-treated patients induced a concentration-dependent prolongation of HR-ACT. Baseline LR-ACT were prolonged in emicizumab-treated patients but as for HR-ACT, emicizumab does not prevent heparin-induced prolongation of LR-ACT.Emicizumab does not interfere with UFH-induced ACT prolongation. The hemochron® ACT can be used to monitor UFH in patients receiving emicizumab during CPB or cardiac catheterization.

Resume Contexte La COVID-19 est associee a un risque thromboembolique veineux eleve, en particulier chez les patients severes. Depuis les premieres propositions GIHP/GFHT publiees en avril 2020, de nouvelles connaissances sont apparues. L’objet du present travail etait de reactualiser ces propositions. Methodes Un groupe de travail a defini sept questions et effectue une revue critique de la litterature. Les propositions ont ete formulees apres consensus entre les membres du groupe de travail et les autres membres du GIHP/GFHT. Resultats Chez les patients hospitalises non severes et certains patients ambulatoires a risque, nous suggerons l’administration d’une thromboprophylaxie a dose standard. Chez les patients severes, nous suggerons une thromboprophylaxie a dose intermediaire ou therapeutique selon le taux de D-dimeres et son evolution. Sept a dix jours apres l’admission, nous suggerons de revenir a une dose standard pour reduire le risque hemorragique. Chez les patients presentant un tres haut risque thrombotique, ayant recu une thromboprophylaxie a dose therapeutique, nous suggerons un depistage systematique de la thrombose avant la desescalade. Nous suggerons d’ajuster l’anticoagulation au poids des patients. Nous suggerons un monitorage regulier des parametres d’hemostase, incluant les D-dimeres, chez les patients severes. Nous suggerons un monitorage de l’anticoagulation a dose intermediaire et therapeutique par l’activite anti-Xa. Conclusion Les propositions reactualisees suivent une approche standard de la thromboprophylaxie, visant a diminuer l’incidence des evenements thromboemboliques veineux symptomatiques. Chez les patients severes, nous proposons une strategie sequentielle tenant compte de la relation temporelle entre le risque thrombotique et le risque hemorragique.

International audience; Background Diagnosis of heparin-induced thrombocytopenia (HIT) requires pretest probability assessment and dedicated laboratory assays.Objective To develop a pretest score for HIT.Design Observational; analysis of prospectively collected data of hospitalized patients suspected with HIT (ClinicalTrials.gov NCT00748839).Setting Thirty-one tertiary hospitals in France, Switzerland, and Belgium.Patients Patients tested for HIT antibodies (2280 evaluable), randomly allocated to derivation and validation cohorts.Measurements Independent adjudicators diagnosed HIT based on the prospectively collected data and serotonin release assay results.Results Heparin-induced thrombocytopenia was diagnosed in 234 (14.7%) and 99 (14.5%) patients in the two cohorts. Eight features were associated with HIT (in brackets, points assigned for score calculation of the score): unfractionated heparin (1); therapeutic-dose heparin (1); cardiopulmonary bypass (cardiac surgery) (2); major trauma (3); 5- to 21-day interval from anticoagulation initiation to suspicion of HIT (4); >= 40% decrease in platelet count over

INTRODUCTION The lack of quality control procedures for home point-of-care (POC) international normalized ratio (INR) devices is a concern. Concomitant laboratory and POC INR testing may be proposed to overcome the lack of quality control. However, a difference between the POC INR and the laboratory INR is not necessarily due to failure of the POC device. This study aimed to identify variables associated with a significant deviation between the POC INR and the laboratory INR. METHODS Children included in this retrospective cohort study performed at least one concomitant laboratory and POC INRs. Clinical and laboratory variables were assessed for an association with significant deviation within pairs of INR. RESULTS A significant deviation was noted for 30 (15.3%) of the 196 pairs of INR measurements from 124 children. Relative to patients without deviations, patients with deviations were younger (odds ratio =0.91; P = .020), less experienced in the use of POC INR devices (odds ratio =0.89; P = .098), and more likely to have received an INR result from a laboratory using animal thromboplastin (odds ratio =2.81 vs. 0.37 for laboratories using human thromboplastin; P = .016). In a multivariate analysis, younger age and the laboratory's use of animal thromboplastin were associated with significant deviations. CONCLUSIONS Although most children had coherent pairs of INR values, the occurrence of deviations raises the question of the origin of the thromboplastin used in the laboratory and emphasizes the need to provide specific quality control procedures for POC INR devices.

Supplemental Digital Content is available in the text., TRIAL REGISTRATION: NCT04420468. OBJECTIVES: Severe acute respiratory syndrome coronavirus 2–related multisystem inflammatory syndrome in children is frequently associated with shock; endothelial involvement may be one of the underlying mechanisms. We sought to describe endothelial dysfunction during multisystem inflammatory syndrome in children with shock and then assess the relationship between the degree of endothelial involvement and the severity of shock. DESIGN: Observational study. SETTING: A PICU in a tertiary hospital. PATIENTS: Patients aged under 18 (n = 28) with severe acute respiratory syndrome coronavirus 2–related multisystem inflammatory syndrome in children and shock, according to the Centers for Disease Control and Prevention criteria. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Correlations between endothelial marker levels and shock severity were assessed using Spearman coefficient. The median (interquartile range) age was 9 years (7.5–11.2 yr). Sixteen children presented with cardiogenic and distributive shock, 10 presented with cardiogenic shock only, and two presented with distributive shock only. The median left ventricular ejection fraction, troponin level, and lactate level were, respectively, 40% (35–45%), 261 ng/mL (131–390 ng/mL), and 3.2 mmol/L (2–4.2 mmol/L). Twenty-five children received inotropes and/or vasopressors; the median Vasoactive and Inotropic Score was 8 (5–28). Plasma levels of angiopoietin-2 (6,426 pg/mL [2,814–11,836 pg/mL]), sE-selectin (130,405 pg/mL [92,987–192,499 pg/mL]), von Willebrand factor antigen (344% [288–378%]), and the angiopoietin-2/angiopoietin-1 ratio (1.111 [0.472–1.524]) were elevated and significantly correlated with the Vasoactive and Inotropic Score (r = 0.45, p = 0.016; r = 0.53, p = 0.04; r = 0.46, p = 0.013; and r = 0.46, p = 0.012, respectively). CONCLUSIONS: Endothelial dysfunction is associated with severe acute respiratory syndrome coronavirus 2–related multisystem inflammatory syndrome in children with shock and may constitute one of the underlying mechanisms.

The lack of quality control for patient point-of-care (POC) INR devices is an issue that has led the French health authorities to make recommendations: a laboratory INR (lab INR) has to be performed at the same time as the POC INR every 6 months. However, the differences observed between the two INRs, POC and lab INRs, are not necessarily due to a failure of the POC INR device. We present here a review of the different causes of discrepancies between INR results, which are the basis of the proposals of the Groupe français d'études sur l'hémostase et la thrombose (GFHT) on the management of lab and POC INR discrepancies. Pre-analytical conditions may account for discrepancies (sampling, transport and storage conditions), as well as analytical factors (mainly the nature of the thromboplastin used) and the clinical context (inflammatory or autoimmune diseases, polycythaemia...). The interpretation of INR discrepancies is not always easy and these proposals aim at standardizing the procedure to be followed in order to make the most appropriate decision for the patient.

Emicizumab, a bispecific humanised monoclonal antibody restoring to some extent the function of activated FVIII deficient in haemophilia A, represents a major therapeutic advance in the management of haemophilia A patients. No dosage adjustment is required, which leads to a major change for patients used to regular biological monitoring which is particularly burdensome in the case of substitution therapy. In some circumstances, such as before an invasive procedure or in case of bleeding, biological monitoring will be necessary and emicizumab's interference with haemostasis tests, particularly those based on an activated partial thromboplastin times (aPTT), must be known to best interpret the tests and to select the most appropriate methods to guide therapy. The normalisation of aPTT in patients treated with emicizumab is not sufficient to consider haemostasis as normalised. In the event of administration of FVIII to a patient receiving emicizumab, the determination of FVIII should use a chromogenic method using non-human reagents. Coagulation global tests have been proposed to evaluate the biological response when using bypassing agents in patients treated with emicizumab, but the usefulness must be confirmed. The French group BIMHO presents proposals for biological monitoring of a patient treated with emicizumab according to clinical situations.

Replacement therapy with plasma-derived or recombinant FVIII and FIX (pdFVIII/pdFIX or rFVIII/rFIX) concentrates is the standard of treatment in patients with haemophilia A and B, respectively. Measurement of factor VIII (FVIII:C) or factor IX (FIX:C) levels can be done by one-stage clotting assay (OSA) or chromogenic substrate assay (CSA). The French study group on the Biology of Hemorrhagic Diseases (a collaborative group of the GFHT and MHEMO network) presents a literature review and proposals for the monitoring of FVIII:C and FIX:C levels in treated haemophilia A and B patients, respectively. The use of CSA is recommended for the monitoring of patients treated with pdFVIII or rFVIII including extended half-life (EHL) rFVIII. Except for rFVIII-Fc, great caution is required when measuring FVIII:C levels by OSA in patients substituted by EHL-rFVIII. The OSA is recommended for the monitoring of patients treated with pdFIX or rFIX. Large discordances in the FIX:C levels measured for extended half-life rFIX (EHL-rFIX), depending on the method and reagents used, must lead to great attention when OSA is used for measuring FIX:C levels in patients substituted by EHL-rFIX. Data of most of recent studies, obtained with spiked plasmas, deserve to be confirmed in plasma samples of treated patients.

After liver transplantation (LT), synthesis of coagulation factors by the graft recovers faster for pro thrombotic than anti thrombotic factors, resulting in a potential pro thrombotic imbalance. We studied the thrombotic and hemorrhagic complications in our pediatric LT series, providing supplementation of fresh frozen plasma (FFP) and/or antithrombin (AT) in the prophylactic antithrombotic regimen.This was a retrospective observational single center study. All isolated pediatric LTs performed between 1/11/2009 and 31/12/2019 (n = 181) were included. Postoperatively, in addition to low molecular weight heparin, 22 patients (12%) received FFP (10 ml/kg twice daily for 10 days), 27 patients (15%) were given FFP (reduced duration) and AT (50-100 IU/kg/day if AT activity remained70%), and 132 (73%) received AT only. Complications, outcome, and coagulation profiles in postoperative days 0-10 were analyzed.In all three treatment groups, AT activity normalized by day 4 while prothrombin remained70% of normal until day 9. Hepatic artery thrombosis (HAT), portal vein thrombosis (PVT), and hemorrhagic complications occurred in 2.8%, 3.3%, and 3.9% of LTs. One- and 5-year patient and graft survival were 88% (±2.4% Standard Error) and 84% (±2.5%), and 86% (±2.6%) and 84% (±2.7%), respectively, without difference between groups. HAT were associated with low AT on days 0 and 1, and PVT with low AT on day 0.Low antithrombin activity after LT was associated with postoperative thromboses. FFP and/or AT supplementation allowed early normalization of AT activity, while thrombotic or hemorrhagic complications were rare, suggesting efficient and safe management of post-LT coagulopathy.

In April 2020, in response to the high thrombotic risk associated with COVID-19, the GIHP and GFHT published proposals for the prevention of venous thromboembolism (VTE) and haemostasis monitoring in patients with COVID-19 [1]. In February 2021, six authors from the proposals (CT, AM, AlG, AnG, SS, YG, PA) decided to update them. This update was justified by several points: - The epidemiology of thrombotic complications has been described. - Different anticoagulation regimens have been reported, and retrospective studies have suggested that higher-than-standard prophylactic anticoagulation may be beneficial. - Initially underestimated, bleeding complications have emerged as a limitation of increased-dose anticoagulation and occur later than thrombotic events. - The first results of large-scale randomised controlled studies on increased doses of anticoagulation have been published. - Immunomodulatory therapies (corticosteroids, interleukin-6 receptor antagonists) are now widely used, but their effect on the thrombotic risk is unknown. - Despite improved survival, thrombotic complications remain a concern [2].

Background Congenital disorders of glycosylation are rare inherited diseases affecting many different proteins. The lack of glycosylation notably affects the hemostatic system and leads to deficiencies of both procoagulant and anticoagulant factors. Objective To assess the hemostatic balance in patients with multiple coagulation disorders by using a thrombin generation assay. Method We performed conventional coagulation assays and a thrombin generation assay on samples from patients with congenital disorder of glycosylation. The thrombin generation assay was performed before and after activation of the protein C system by the addition of soluble thrombomodulin. Results A total of 35 patients were included: 71% and 57% had low antithrombin and factor XI levels, respectively. Protein C and protein S levels were abnormally low in 29% and 26% of the patients, respectively, whereas only 11% displayed low factor IX levels. Under baseline conditions, the thrombin generation assay revealed a significantly higher endogenous thrombin potential and thrombin peak in patients, relative to controls. After spiking with thrombomodulin, we observed impaired involvement of the protein C system. Hence, 54% of patients displayed a hypercoagulant phenotype in vitro. All the patients with a history of stroke-like episodes or thrombosis displayed this hypercoagulant phenotype. Conclusion A thrombin generation assay revealed a hypercoagulant in vitro phenotype under baseline condition; this was accentuated by impaired involvement of the protein C system. This procoagulant phenotype may thus reflect the risk of severe vascular complications. Further research will have to determine whether the thrombin generation assay is predictive of vascular events.

International audience; Introduction Emicizumab (Hemlibra (R)) recently became available and requires an adaptation for managing bleeding, suspected bleeding and emergency or scheduled invasive procedures in haemophilia A patients with inhibitor. This implicates a multidisciplinary approach and redaction of recommendations for care that must be regularly adapted to the available data. Aim The following text aims to provide a guide for the management of people with haemophilia A with inhibitor treated with emicizumab in case of bleeding or invasives procedures. Methods The French network on inherited bleeding disorders (MHEMO), the French Reference Centre on Haemophilia (CRH), in collaboration with the French Working Group on Perioperative Haemostasis (GIHP) have been working together to make proposals for the management of these situations. Results Haemostatic treatment and other medications should be given stepwise, according to the severity and location of the bleeding or the risk of bleeding of the procedure as well as the haemostatic response obtained at each step in order to ensure an optimal benefit/risk ratio. Conclusion The lack of data means that it is only possible to issue proposals rather than recommendations.

Le Groupe d’intérêt en hémostase périopératoire (GIHP) et le Groupe français d’études sur l’hémostase et la thrombose (GFHT), en collaboration avec la Société française d’anesthésie et de réanimation (SFAR) ont fait des propositions de gestion des agents antiplaquettaires (AAP) pour une procédure invasive programmée. Ces propositions ont été discutées et validées par vote ; toutes sauf une ont fait l’objet d’un accord fort. La gestion des AAP dépend de leur indication et de la procédure considérée. Le risque hémorragique lié à la procédure invasive peut être divisé en bas, intermédiaire ou élevé, selon la possibilité ou non de réaliser la procédure sous traitement (sous respectivement bithérapie antiplaquettaire, aspirine en monothérapie ou aucun AAP). Si une interruption des AAP est indiquée avant la procédure, une dernière prise d’aspirine, clopidogrel, ticagrélor et prasugrel 3, 5, 5 et 7 jours avant la procédure est proposée. Le risque thrombotique associé à l’interruption des AAP doit être évalué en fonction de l’indication des AAP. Il est plus élevé chez les patients traités par bithérapie pour un stent coronaire que chez ceux traités par monothérapie pour une prévention cardiovasculaire, un antécédent d’accident vasculaire cérébral ischémique ou une artériopathie oblitérante des membres inférieurs. Ces propositions concernent aussi le rôle potentiel des tests fonctionnels plaquettaires, la gestion des AAP pour l’anesthésie locorégionale, centrale et périphérique, et pour la chirurgie cardiaque coronaire.

Resume L’hemostase du nouveau-ne presente de nombreuses particularites qui doivent etre connues des equipes medicales impliquees dans le diagnostic et le traitement des anomalies de la coagulation. Le systeme de l’hemostase du nouveau-ne est decrit comme un systeme en developpement, reflet des changements quantitatifs et qualitatifs presents dans la premiere annee de vie mais aussi dans la periode fœtale. L’interpretation des examens biologiques d’hemostase doit tenir compte des valeurs de references specifiques a chaque tranche d’âge et a chaque systeme analyseurs reactifs, de l’âge post natal et gestationnel mais aussi des difficultes preanalytiques frequemment rencontrees lors du prelevement d’un nouveau-ne. La majorite des pathologies hemorragiques et thrombotiques chez le nouveau-ne ont une origine acquise. Seules les anomalies constitutionnelles severes homozygotes ou heterozygotes composites sont revelees par des complications neonatales. Une bonne connaissance des particularites du systeme de l’hemostase du nouveau-ne est necessaire pour la gestion des traitements anticoagulants.

Lowe syndrome (LS) is an oculocerebrorenal syndrome of Lowe (OCRL1) genetic disorder resulting in a defect of the OCRL protein, a phosphatidylinositol-4,5-bisphosphate 5-phosphatase containing various domains including a Rho GTPase-activating protein (RhoGAP) homology domain catalytically inactive. We previously reported surgery-associated bleeding in patients with LS, suggestive of platelet dysfunction, accompanied with a mild thrombocytopenia in several patients. To decipher the role of OCRL in platelet functions and in megakaryocyte (MK) maturation, we conducted a case-control study on 15 patients with LS (NCT01314560). While all had a drastically reduced expression of OCRL, this deficiency did not affect platelet aggregability, but resulted in delayed thrombus formation on collagen under flow conditions, defective platelet spreading on fibrinogen and impaired clot retraction. We evidenced alterations of the myosin light chain phosphorylation (P-MLC), with defective Rac1 activity and, inversely, elevated active RhoA. Altered cytoskeleton dynamics was also observed in cultured patient MKs showing deficient proplatelet extension with increased P-MLC that was confirmed using control MKs transfected with OCRL-specific small interfering(si)RNA (siOCRL). Patients with LS also had an increased proportion of circulating barbell-shaped proplatelets. Our present study establishes that a deficiency of the OCRL protein results in a defective actomyosin cytoskeleton reorganisation in both MKs and platelets, altering both thrombopoiesis and some platelet responses to activation necessary to ensure haemostasis.

Heparin-induced thrombocytopenia (HIT) is a rare, iatrogenic disease characterised by its potential severity, mainly related to thrombosis, and by difficulties regarding its diagnosis and management of affected patients. In 2002, a conference of experts mobilised by the French Society of Anaesthesia and Intensive Care Medicine (Société française d’anesthésie et de réanimation [SFAR]) drafted recommendations for the management of HIT [...]

Resume Chez l’enfant, et plus particulierement chez le nouveau-ne, les mecanismes complexes, qui permettent la prevention des hemorragies et des thromboses en associant l’action des plaquettes et de nombreuses proteines de la coagulation et de la fibrinolyse, presentent d’importantes particularites par rapport a l’adulte. Le systeme de l’hemostase est decrit comme « immature » et en developpement, ce qui reflete les changements quantitatifs et qualitatifs presents des la periode fœtale, se poursuivant chez le nouveau-ne et chez l’enfant. Neanmoins, l’hemostase du nouveau-ne a terme reste equilibree, sans saignements ni thromboses, mais cet equilibre est fragile. L’histoire clinique de l’enfant avant l’âge de la marche etant insuffisante, l’exploration biologique de l’hemostase va etre capitale pour apprecier un eventuel risque hemorragique avant un geste invasif. L’interpretation des examens biologiques d’hemostase devra tenir compte des particularites physiologiques, les valeurs de reference etant specifiques a chaque tranche d’âge, mais aussi d’eventuels antecedents hemorragiques personnels et/ou familiaux. Elle devra egalement prendre en compte les possibles interferences pre-analytiques, en particulier liees aux difficultes de prelevement, pouvant interferer sur les resultats. Cette revue abordera egalement les principales pathologies de l’hemostase susceptibles d’etre decouvertes lors d’un bilan preoperatoire en pediatrie.

Sickle cell disease (SCD) complications mostly result from vascular dysfunction, concerning systemic microvasculature and cerebral large vessels. The aim of this cohort study was to identify potential circulating biomarkers predictive for further vascular event occurrence in pediatric SCD. We consecutively enrolled 108 children with SCD at steady state, aged 3–18 years old (median 9.8 years). Hematology, coagulation, hemolysis, endothelial, platelet and vascular activation parameters were recorded at inclusion. Neurovascular and systemic vascular events were prospectively recorded during a mean follow-up period of 27 months. Patients at steady state displayed significantly higher hemolysis and platelet activation markers, higher leukocyte, CD34+ hematopoietic stem cell and microvesicle counts, and a pro-coagulant profile compared to controls matched for age and ethnicity. Circulating endothelial cell or nucleosome level did not differ. During the follow-up period, 36 patients had at least one neurovascular (n = 12) or systemic vascular event (n = 25). In a multivariate model, high CD34+ cell count was the best predictor for the occurrence of a vascular event (OR 1.2 for 1000 cell/mL increase, 95% CI [1.049–1.4], p = 0.013, sensitivity 53%, specificity 84% for a threshold of 8675 cells/mL). CD34+ cell count at steady state is a promising biomarker of further vascular event in children with SCD.

International audience; Argatroban is a direct anti-IIa (thrombin) anticoagulant, administered as a continuous intravenous infusion; it has been approved in many countries for the anticoagulant management of heparin-induced thrombocytopaenia (HIT). Argatroban was recently proposed as the non-heparin anticoagulant of choice for the management of patients diagnosed with Vaccine-induced Immune Thrombotic Thrombocytopaenia (VITT). Immunoglobulins are also promptly intravenously administered in order to rapidly improve platelet count; concomitant therapy with steroids is also often considered. An ad hoc committee of the French Working Group on Haemostasis and Thrombosis members has worked on updated and detailed proposals regarding the management of anticoagulation with argatroban, based on previously released guidance for HIT, and adapted for VITT. In case of VITT, the initial dose to be preferred is 1.0 µg × kg(-1) × min(-1), with further dose-adjustments based on iterative and frequent clinical and laboratory assessments. It is strongly advised to involve a health practitioner experienced in the management of difficult cases in haemostasis. The first laboratory assessment should be performed 4 h after the initiation of argatroban infusion, with further controls at 2-4-h intervals until steady state, and at least once daily thereafter. Importantly, full anticoagulation should be rapidly achieved in case of widespread thrombosis. Cerebral vein thrombosis (which is typical of VITT) should not call for an overly cautious anticoagulation scheme. Argatroban administration requires baseline laboratory assessment and should rely on an anti-IIa assay to derive argatroban plasma levels using a dedicated calibration, with a target range between 0.5 and 1.5 µg/mL. Target argatroban plasma levels can be refined based on meticulous appraisal of risk factors for bleeding and thrombosis, on frequent reassessments of clinical status with appropriate vascular imaging, and on the changes in daily platelet counts. Regarding the use of aPTT, baseline value and possible causes for alterations of the clotting time must be taken into account. Specifically, in case of VITT, an aPTT ratio (patient’s/mean normal clotting time) between 1.5 and 2.5 is suggested, to be refined according to the sensitivity of the reagent to the effect of a direct thrombin inhibitor. The sole use of aPTT is discouraged: one has to resort to a periodical check with an anti-IIa assay at least, with the help of a specialised laboratory if necessary. Dose modifications should proceed in a stepwise manner with 0.1 to 0.2 µg × kg(-1) × min(-1) up- or downward changes, taking into account the initial dose, laboratory results, and the whole individual setting. Nomograms are available to adjust the infusion rate. Haemoglobin level, platelet count, fibrinogen plasma level and liver tests should be periodically checked, depending on the clinical status, the more so when unstable.

Hemophilia A carriers have an abnormal X chromosome with a molecular abnormality of FVIII gene. These carriers, long considered to be free of bleeding risk, could have the same symptoms as mild hemophiliacs. This study aim to assess bleeding risk of hemophilia A carriers monitored at the Clinical Hematology Department of Dakar. This is a prospective study of a period of 6 months including 22 hemophilia A carriers aged between 8 and 48 years. Hemophilia carriers were recruited using the genealogical tree of hemophiliacs followed in the service. Their diagnosis was carried out by long range PCR and Sanger sequencing method searching the molecular abnormality responsible for hemophilia in their family. Bleeding risk was determined using a questionnaire consisting of different bleeding symptoms quoted from -1 to 4 according to the severity. Total of different values allow to determine the bleeding score which was pathological if it was greater than or equal to 1. Medium age was 22.5 years (8-48) (SD = 9.28). Four hemophilia A carriers (18.1%) presented bleeding symptoms and had a bleeding score at least 1 (P = 0.02). Menorrhagia was predominant (13.6%) followed by epistaxis (9%), gingivorrhagia (9%), and prolonged bleeding after tooth extraction (9%). Factor VIII level was lower in hemophilia carriers who presented bleeding (42 ± 8.61 UI/l) versus hemophilia carriers without bleeding (100 ± 50.95 UI/l) (P = 0.001). There was no significant correlation between bleeding occurrence and age (P = 0.81), activated patial thromboplastin time value (P = 0.97) and FVIII/Von Willebrand Factor ratio (P = 0.12). One in five hemophilia carriers presented bleeding and the questionnaire was effective to identify hemophilia carriers who had a risk of bleeding.

Deep vein thrombosis is a common disease associated with a variety of complications including post-thrombotic syndrome as a late complication. It is now clear that in addition to classical deep vein thrombosis triggers such as blood flow disturbance, hypercoagulability, and vessel wall changes, inflammation has a key role in the pathophysiology of deep vein thrombosis, and there is a close relationship between inflammation and coagulation. As attested by changes in several plasma biomarkers, inflammation may have a significant role in the development of post-thrombotic syndrome. Here, we review the link between inflammation and deep vein thrombosis and thus the potential value of anti-inflammatory and/or anticoagulant drugs in the treatment of deep vein thrombosis and the prevention of post-thrombotic syndrome.

The genetic causes of congenital hypothyroidism due to thyroid dysgenesis (TD) remain largely unknown. We identified three novel TUBB1 gene mutations that co‐segregated with TD in three distinct families leading to 1.1% of TUBB1 mutations in TD study cohort. TUBB1 (Tubulin, Beta 1 Class VI) encodes for a member of the β‐tubulin protein family. TUBB1 gene is expressed in the developing and adult thyroid in humans and mice. All three TUBB1 mutations lead to non‐functional α/β‐tubulin dimers that cannot be incorporated into microtubules. In mice, Tubb1 knock‐out disrupted microtubule integrity by preventing β1‐tubulin incorporation and impaired thyroid migration and thyroid hormone secretion. In addition, TUBB1 mutations caused the formation of macroplatelets and hyperaggregation of human platelets after stimulation by low doses of agonists. Our data highlight unexpected roles for β1‐tubulin in thyroid development and in platelet physiology. Finally, these findings expand the spectrum of the rare paediatric diseases related to mutations in tubulin‐coding genes and provide new insights into the genetic background and mechanisms involved in congenital hypothyroidism and thyroid dysgenesis.

The French Working Group on Perioperative Haemostasis (GIHP)and the French Study Group on Haemostasis and Thrombosis (GFHT)in collaboration with the French Society of Anaesthesia and Intensive Care Medicine (SFAR)drafted up-to-date proposals on the management of antiplatelet therapy for non-elective invasive procedures or bleeding complications. The proposals were discussed and validated by a vote; all proposals could be assigned with a high strength. Emergency management of oral antiplatelet agents (APA)requires knowledge on their pharmacokinetic/pharmacodynamics parameters, evaluation of the degree of the alteration of haemostatic competence and the associated bleeding risk. Platelet function testing may be considered. When APA-induced bleeding risk may worsen the prognosis, measures should be taken to neutralise antiplatelet therapy by considering not only the efficacy of available means (which can be limited for prasugrel and even more for ticagrelor)but also the risks that these means expose the patient to. The measures include platelet transfusion at the appropriate dose and haemostatic agents (tranexamic acid; rFVIIa for ticagrelor). When possible, postponing non-elective invasive procedures at least for a few hours until the elimination of the active compound (which could compromise the effect of transfused platelets)or if possible a few days (reduction of the effect of APA)should be considered., SCOPUS: ar.j, info:eu-repo/semantics/published

International audience; Replacement therapy with plasma-derived or recombinant FIX (pdFIX or rFIX) concentrates is the standard of treatment in patients with hemophilia B. The method predominantly used for measuring factor IX (FIX:C) levels is the one-stage clotting assay (OSA) but this method depends on the activated partial thromboplastin time (APTT) reagent and the coagulation analyzer used, and wide variations in the measurements of FIX recovery have been reported with some factor concentrates. The French study group on the biology of hemorrhagic diseases (a collaborative group of the GFHT and MHEMO network), presents a review of the literature and proposals for the monitoring of FIX:C levels in treated hemophilia B patients. The use of OSA calibrated with a plasma reference tested against the current FIX WHO International Standard is recommended for the monitoring of patients treated with pdFIX or rFIX. Chromogenic substrate assays (CSA) are adequate for the monitoring of patients treated with Rixubis®, but data available for Benefix® are currently too limited. For extended half-life rFIX (EHL-rFIX), large discordances in the FIX:C levels measured were evidenced, depending on the method and reagents used. Great attention is therefore required for measuring FIX:C levels by OSA in patients substituted by EHL-rFIX. Commercial kits for CSA are not equivalent, and although potentially useful, they are not validated for all EHL-rFIX. Most of recent studies reported data obtained with spiked plasmas, which deserve to be confirmed on plasma samples collected in treated patients.

Background: Diagnosis of heparin-induced thrombocytopenia (HIT) is based on a composite of clinical likelihood and laboratory testing. We aimed to develop a diagnostic score derived from multivariate analysis of clinical features, including platelet count changes, prospectively recorded in patients with suspected HIT. Methods: This multinational observational study (ClinicalTrials.gov no. NCT00748839) included 2280 adult patients with suspected HIT: 1597 (derivation cohort) formed the basis for developing the scoring system, subsequently validated in 683 additional randomly selected patients (validation cohort). HIT was diagnosed by two independent adjudicators based on clinical features, local laboratory data, and the results of a centrally performed serotonin release assay (SRA). Findings: Overall, 56.7% of the patients were treated in an intensive care unit of whom 57.4% received unfractionated heparin; thromboembolism occurred in 12.3%. In the derivation and validation cohorts, 234 (14.7%) and 99 (14.5%) patients, respectively, were diagnosed with HIT. Eight features were positively associated with HIT diagnosis in a multivariate model (in brackets the value assigned for score calculation): unfractionated heparin use (1); therapeutic-dose heparin use (1); cardiac surgery with cardiopulmonary bypass (2); major trauma (3); 5- to 21-day interval from anticoagulant treatment initiation to suspicion of HIT (4); ≥ 40% decrease in platelet count over ≤ 6 days during the last 10 days of anticoagulation exposure (3); thrombotic event, either arterial (3) or venous (3). The C statistic of the model was 0.791 [0.76; 0.82] (p-value 0.70, Hosmer-Lemeshow test). In the validation cohort, the area under the ROC curve was 0.77 [95% CI 0.74-0.80], and HIT prevalence was 2.6% for a score ≤2; 6% for a score of 3–8; and 28.8% for a score >8: Interpretation: This study distinguishes validated clinical features of HIT, permitting improved estimation of its likelihood. Trial Registration: (ClinicalTrials.gov no. NCT00748839) Funding Statement: Programme Hospitalier de Recherche Clinique (French Health Ministry), Sanofi, LFB, Organon SA. Declaration of Interests: Dr. Mullier reports personal fees from Aspen, personal fees from Stago, grants from Werfen, outside the submitted work; Dr. Gruel reports personal fees from Sanofi, personal fees from LFB, other from Stago, personal fees from Aspen, outside the submitted work; . All other authors declare no conflict of interests. Ethics Approval Statement: The study was conducted in accordance with the ethical principles stated in the Declaration of Helsinki, Good Clinical Practice, and relevant French, Swiss and Belgian legal and regulatory requirements regarding data protection. The protocol was approved by French, Swiss and Belgian independent ethics committees. All patients received written information about the study, emphasizing their right to refuse participation or to withdraw at any time. As no experimental interventions were induced from the protocol, no written informed consent was required for inclusion.

International audience; Reliable laboratory diagnosis of heparin-induced thrombocytopenia (HIT) remains a major clinical concern. Immunoassays are highly sensitive, while confirmatory functional tests (based on heparin-dependent platelet activation) lack standardization. We evaluated the diagnostic performance of a functional flow cytometric assay (FCA) based on the detection of heparin-dependent platelet activation with an anti-p-selectin. A total of 288 patients were included (131 HIT-positive and 157 HIT-negative) with a HIT diagnosis established by expert opinion adjudication (EOA) considering clinical data and local laboratory results. The FCA was centrally performed in a single laboratory on platelet-rich plasma, using a very simple four-color fluorometer. The results were standardized according to the Heparin Platelet Activation (HEPLA) index. The serotonin release assay (SRA) was performed in the four French reference laboratories. Based on the final HIT diagnosis established by EOA, the sensitivity and specificity of the FCA were 88 and 95%, respectively, values very similar to those of the SRA (88 and 97%, respectively). This study showed that the FCA, based on easily implementable technology, may be routinely used as a reliable confirmatory test for HIT diagnosis.

SummaryIn the absence of specific antidote to fondaparinux, two modified forms of antithrombin (AT), one recombinant inactive (ri-AT) and the other chemically inactivated (chi-AT), were designed to antagonise AT-mediated anticoagulants, e. g. heparins or fondaparinux. These inactive ATs were previously proven to effectively neutralise anticoagulant activity associated with heparin derivatives in vitro and in vivo, as assessed by direct measurement of anti-FXa activity. This study was undertaken to evaluate in vitro the effectivity of inactive ATs to reverse anticoagulation by heparin derivatives and to compare them with non-specific fondaparinux reversal agents, like recombinant-activated factor VII (rFVIIa) or activated prothrombin-complex concentrate (aPCC), in a thrombin-generation assay (TGA). Addition of fondaparinux (3 μg/ml) to normal plasma inhibited thrombin generation by prolonging lag time (LT) as much as 244 % and lowering endogenous thrombin potential (ETP) to 17 % of their control (normal plasma) values. Fondaparinux-anticoagulant activity was reversed by ri-AT and chi-AT, as reflected by the corrections of LT up to 117 % and 114 % of its control value, and ETP recovery to 78 % and 63 %, respectively. Unlike ri-AT that had no effect on thrombin generation in normal plasma, chi-AT retained anticoagulant activity that minimises its reversal capacity. However, both ATs were more effective than rFVIIa or aPCC at neutralising fondaparinux and, unlike non-specific antidotes, inactive ATs specifically reversed AT-mediated anticoagulant activities, as suggested by their absence of procoagulant activity in anticoagulant-free plasma.

Kasabach-Merritt phenomenon (KMP) is a rare life-threatening vascular condition of infancy. Prognosis factors and long-term follow-up data are lacking. We retrospectively analysed the records of 24 infants (10 females, 14 males) treated for KMP in the Department of Dermatology of Necker-Enfants Malades Hospital, Paris, France, from 1984 to 2012. Mean duration of thrombocytopaenia (2,000-38,000 platelets/mm3, mean 10,500/µl) was 8.8 months (range 3 days-84 months), which correlated with tumour infiltration depth on imaging. D-dimer levels were always elevated, even before KMP onset. Each patient received a mean of 4.8 different treatments (range 1-10). Median follow-up was 6.5 years (range 2 months-22 years). All infants had residual cutaneous lesions, along with inflammatory manifestations (n = 9), elevated D-dimer (n = 5) and orthopaedic sequelae (n = 5). The permanent coagulopathy (elevated D-dimer) even after resolution of KMP suggests the presence of chronic low-grade platelet trapping, with possible sudden worsening, and raises the possibility of prophylactic anti-platelet therapy.

The French Working Group on Perioperative Haemostasis (GIHP) and the French Study Group on Haemostasis and Thrombosis (GFHT), in collaboration with the French Society for Anaesthesia and Intensive Care (SFAR), drafted up-to-date proposals on the management of antiplatelet therapy for non-elective invasive procedures or bleeding complications. The proposals were discussed and validated by a vote; all proposals could be assigned with a high strength. Management of oral antiplatelet agents in emergency settings requires knowledge of their pharmacokinetic and pharmacodynamic parameters, evaluation of the degree of alteration of haemostatic competence and the associated bleeding risk. Platelet function testing may be considered. When antiplatelet agent-induced bleeding risk may worsen the prognosis, measures should be taken to neutralize antiplatelet therapy, by considering not only the efficacy of available means (which can be limited for prasugrel and even more for ticagrelor), but also the risks that these means expose the patient to. The measures include platelet transfusion at the appropriate dose and haemostatic agents (tranexamic acid; recombinant activated factor VII for ticagrelor). When possible, postponing non-elective invasive procedures at least for a few hours until the elimination of the active compound (which could compromise the effect of transfused platelets) or, if possible, for a few days (reduction of the effect of antiplatelet agents) should be considered.

Point of care testing (POCT) must comply with regulatory requirements according to standard EN ISO 22870, which identify biologists as responsible for POCT. INR for vitamin K antagonists (VKAs) monitoring is a test frequently performed in haemostasis laboratories. Bedside INR is useful in emergency room, in particular in case of VKAs overdosage but also for specific populations of patients like paediatrics or geriatrics. INR POCT devices are widely used at home by the patients for self-testing, but their use in the hospital by the clinical staff for bedside measurement is growing, with devices which now comply with standard for POCT accreditation for hospital use. The majority of point of care devices for INR monitoring has shown a good precision and accuracy with results similar to those obtained in laboratory. With the aim to help the multidisciplinary groups for POCT supervision, the medical departments and the biologists to be in accordance with the standard, we present the guidelines of the GFHT (Groupe francais d'etude sur l'hemostase et la thrombose, subcommittee "CEC et biologie delocalisee") for the certification of POCT INR. These guidelines are based on the SFBC guidelines for the certification of POCT and on the analysis of the literature to ascertain the justification of clinical need and assess the analytical performance of main analysers used in France, as well as on a survey conducted with biologists.