Women and girls with inherited bleeding disorders: Focus on haemophilia carriers and heavy menstrual bleeding

Raising awareness and improving recognition, accurate classification, and enhanced access to new treatments represent current key challenges for carriers of haemophilia. Women and girls carrying genes for haemophilia often experience significant bleeding and/or low factor levels. The bleeding associated with female haemophilia is frequently overlooked, has a weak correlation with factor levels, and manifests differently than in males, with heavy menstrual bleeding being a predominant symptom. Recent changes in terminology now allow the diagnosis of haemophilia in females with low factor levels and differentiate between symptomatic and asymptomatic carriers of the gene. Observations from real-world experiences and limited clinical trial data have highlighted the positive impact of various new haemophilia treatments for women and girls with clotting factor deficiencies. There is an urgent need for initiatives that increase their access to these treatments and encourage well-designed clinical trials focusing on female-specific outcomes. In women with inherited bleeding disorders, early recognition and optimal management of heavy menstrual bleeding are crucial. However, treatment options and guidance from high-quality clinical trials are currently insufficient. Menstrual health assessment should be a regular part of monitoring women and girls with inherited bleeding disorders throughout their lives, emphasizing the importance of gathering data to improve future management.

Standardization of definition and management for bleeding disorder of unknown cause: communication from the SSC of the ISTH

In many patients referred with significant bleeding phenotype, laboratory testing fails to define any hemostatic abnormalities. Clinical practice with respect to diagnosis and management of this patient cohort poses significant clinical challenges. We recommend that bleeding history in these patients should be objectively assessed using the International Society on Thrombosis and Haemostasis (ISTH) bleeding assessment tool. Patients with increased bleeding assessment tool scores should progress to hemostasis laboratory testing. To diagnose bleeding disorder of unknown cause (BDUC), normal complete blood count, prothrombin time, activated partial thromboplastin time, thrombin time, von Willebrand factor antigen, von Willebrand factor function, coagulation factors VIII, IX, and XI, and platelet light transmission aggregometry should be the minimum laboratory assessment. In some laboratories, additional specialized hemostasis testing may be performed to identify other rare causes of bleeding. We recommend that patients with a significant bleeding phenotype but normal laboratory investigations should be registered with a diagnosis of BDUC in preference to other terminology. Global hemostatic tests and markers of fibrinolysis demonstrate variable abnormalities, and their clinical significance remains uncertain. Targeted genomic sequencing examining candidate hemostatic genes has a low diagnostic yield. Underlying BDUC should be considered in patients with heavy menstrual bleeding since delays in diagnosis often extend to many years and negatively impact quality of life. Treatment options for BDUC patients include tranexamic acid, desmopressin, and platelet transfusions.

A novel method to quantify fibrin-fibrin and fibrin-α2-antiplasmin cross-links in thrombi formed from human trauma patient plasma

BACKGROUND

The widespread use of the antifibrinolytic agent, tranexamic acid (TXA), interferes with the quantification of fibrinolysis by dynamic laboratory assays such as clot lysis, making it difficult to measure fibrinolysis in many trauma patients. At the final stage of coagulation, factor (F)XIIIa catalyzes the formation of fibrin-fibrin and fibrin-α2-antiplasmin (α2AP) cross-links, which increases clot mechanical strength and resistance to fibrinolysis.

OBJECTIVES

Here, we developed a method to quantify fibrin-fibrin and fibrin-α2AP cross-links that avoids the challenges posed by TXA in determining fibrinolytic resistance in conventional assays.

METHODS

Fibrinogen alpha (FGA) chain (FGA-FGA), fibrinogen gamma (FGG) chain (FGG-FGG), and FGA-α2AP cross-links were quantified using liquid chromatography-mass spectrometry (LC-MS) and parallel reaction monitoring in paired plasma samples from trauma patients prefibrinogen and postfibrinogen replacement. Differences in the abundance of cross-links in trauma patients receiving cryoprecipitate (cryo) or fibrinogen concentrate (Fg-C) were analyzed.

RESULTS

The abundance of cross-links was significantly increased in trauma patients postcryo, but not Fg-C transfusion (P < .0001). The abundance of cross-links was positively correlated with the toughness of individual fibrin fibers, the peak thrombin concentration, and FXIII antigen (P < .05).

CONCLUSION

We have developed a novel method that allows us to quantify fibrin cross-links in trauma patients who have received TXA, providing an indirect measure of fibrinolytic resistance. Using this novel approach, we have avoided the effect of TXA and shown that cryo increases fibrin-fibrin and fibrin-α2AP cross-linking when compared with Fg-C, highlighting the importance of FXIII in clot formation and stability in trauma patients.

Contemporary management of major haemorrhage in critical care

Haemorrhagic shock is frequent in critical care settings and responsible for a high mortality rate due to multiple organ dysfunction and coagulopathy. The management of critically ill patients with bleeding and shock is complex, and treatment of these patients must be rapid and definitive. The administration of large volumes of blood components leads to major physiological alterations which must be mitigated during and after bleeding. Early recognition of bleeding and coagulopathy, understanding the underlying pathophysiology related to specific disease states, and the development of individualised management protocols are important for optimal outcomes. This review describes the contemporary understanding of the pathophysiology of various types of coagulopathic bleeding; the diagnosis and management of critically ill bleeding patients, including major haemorrhage protocols and post-transfusion management; and finally highlights recent areas of opportunity to better understand optimal management strategies for managing bleeding in the intensive care unit (ICU).

A new population pharmacokinetic model for recombinant factor IX-Fc fusion concentrate including young children with haemophilia B

AIMS

Recombinant factor IX Fc fusion protein (rFIX-Fc) is an extended half-life factor concentrate administered to haemophilia B patients. So far, a population pharmacokinetic (PK) model has only been published for patients aged ≥12 years. The aim was to externally evaluate the predictive performance of the published rFIX-Fc population PK model for patients of all ages and develop a model that describes rFIX-Fc PK using real-world data.

METHODS

We collected prospective and retrospective data from patients with haemophilia B treated with rFIX-Fc and included in the OPTI-CLOT TARGET study (NTR7523) or United Kindom (UK)-EHL Outcomes Registry (NCT02938156). Predictive performance was assessed by comparing predicted with observed FIX activity levels. A new population PK model was constructed using nonlinear mixed-effects modelling.

RESULTS

Real-world data were obtained from 37 patients (median age: 16 years, range 2-71) of whom 14 were aged <12 years. Observed FIX activity levels were significantly higher than levels predicted using the published model, with a median prediction error of -48.8%. The new model showed a lower median prediction error (3.4%) and better described rFIX-Fc PK, especially for children aged <12 years. In the new model, an increase in age was correlated with a decrease in clearance (P < .01).

CONCLUSIONS

The published population PK model significantly underpredicted FIX activity levels. The new model better describes rFIX-Fc PK, especially for children aged <12 years. This study underlines the necessity to strive for representative population PK models, thereby avoiding extrapolation outside the studied population.

Early and Empirical High-Dose Cryoprecipitate for Hemorrhage After Traumatic Injury: The CRYOSTAT-2 Randomized Clinical Trial

Importance

Critical bleeding is associated with a high mortality rate in patients with trauma. Hemorrhage is exacerbated by a complex derangement of coagulation, including an acute fibrinogen deficiency. Management is fibrinogen replacement with cryoprecipitate transfusions or fibrinogen concentrate, usually administered relatively late during hemorrhage.

Objective

To assess whether survival could be improved by administering an early and empirical high dose of cryoprecipitate to all patients with trauma and bleeding that required activation of a major hemorrhage protocol.

Design, Setting, and Participants

CRYOSTAT-2 was an interventional, randomized, open-label, parallel-group controlled, international, multicenter study. Patients were enrolled at 26 UK and US major trauma centers from August 2017 to November 2021. Eligible patients were injured adults requiring activation of the hospital's major hemorrhage protocol with evidence of active hemorrhage, systolic blood pressure less than 90 mm Hg at any time, and receiving at least 1 U of a blood component transfusion.

Intervention

Patients were randomly assigned (in a 1:1 ratio) to receive standard care, which was the local major hemorrhage protocol (reviewed for guideline adherence), or cryoprecipitate, in which 3 pools of cryoprecipitate (6-g fibrinogen equivalent) were to be administered in addition to standard care within 90 minutes of randomization and 3 hours of injury.

Main Outcomes and Measures

The primary outcome was all-cause mortality at 28 days in the intention-to-treat population.

Results

Among 1604 eligible patients, 799 were randomized to the cryoprecipitate group and 805 to the standard care group. Missing primary outcome data occurred in 73 patients (principally due to withdrawal of consent) and 1531 (95%) were included in the primary analysis population. The median (IQR) age of participants was 39 (26-55) years, 1251 (79%) were men, median (IQR) Injury Severity Score was 29 (18-43), 36% had penetrating injury, and 33% had systolic blood pressure less than 90 mm Hg at hospital arrival. All-cause 28-day mortality in the intention-to-treat population was 26.1% in the standard care group vs 25.3% in the cryoprecipitate group (odds ratio, 0.96 [95% CI, 0.75-1.23]; P = .74). There was no difference in safety outcomes or incidence of thrombotic events in the standard care vs cryoprecipitate group (12.9% vs 12.7%).

Conclusions and Relevance

Among patients with trauma and bleeding who required activation of a major hemorrhage protocol, the addition of early and empirical high-dose cryoprecipitate to standard care did not improve all cause 28-day mortality.

Trial Registration

ClinicalTrials.gov Identifier: NCT04704869; ISRCTN Identifier: ISRCTN14998314.

A new global fibrinolysis capacity assay for the sensitive detection of hyperfibrinolysis and hypofibrinogenemia in trauma patients

BACKGROUND

Conventional clotting tests are not expeditious enough to allow timely targeted interventions in trauma, and current point-of-care analyzers, such as rotational thromboelastometry (ROTEM), have limited sensitivity for hyperfibrinolysis and hypofibrinogenemia.

OBJECTIVES

To evaluate the performance of a recently developed global fibrinolysis capacity (GFC) assay in identifying fibrinolysis and hypofibrinogenemia in trauma patients.

METHODS

Exploratory analysis of a prospective cohort of adult trauma patients admitted to a single UK major trauma center and of commercially available healthy donor samples was performed. Lysis time (LT) was measured in plasma according to the GFC manufacturer's protocol, and a novel fibrinogen-related parameter (percentage reduction in GFC optical density from baseline at 1 minute) was derived from the GFC curve. Hyperfibrinolysis was defined as a tissue factor-activated ROTEM maximum lysis of >15% or LT of ≤30 minutes.

RESULTS

Compared to healthy donors (n = 19), non-tranexamic acid-treated trauma patients (n = 82) showed shortened LT, indicative of hyperfibrinolysis (29 minutes [16-35] vs 43 minutes [40-47]; p < .001). Of the 63 patients without overt ROTEM-hyperfibrinolysis, 31 (49%) had LT of ≤30 minutes, with 26% (8 of 31) of them requiring major transfusions. LT showed increased accuracy compared to maximum lysis in predicting 28-day mortality (area under the receiver operating characteristic curve, 0.96 [0.92-1.00] vs 0.65 [0.49-0.81]; p = .001). Percentage reduction in GFC optical density from baseline at 1 minute showed comparable specificity (76% vs 79%) to ROTEM clot amplitude at 5 minutes from tissue factor-activated ROTEM with cytochalasin D in detecting hypofibrinogenemia but correctly reclassified >50% of the patients with false negative results, leading to higher sensitivity (90% vs 77%).

CONCLUSION

Severe trauma patients are characterized by a hyperfibrinolytic profile upon admission to the emergency department. The GFC assay is more sensitive than ROTEM in capturing hyperfibrinolysis and hypofibrinogenemia but requires further development and automation.

Experimental Models of Traumatic Injuries: Do They Capture the Coagulopathy and Underlying Endotheliopathy Induced by Human Trauma?

Trauma-induced coagulopathy (TIC) is a major cause of morbidity and mortality in patients with traumatic injury. It describes the spectrum of coagulation abnormalities that occur because of the trauma itself and the body's response to the trauma. These coagulation abnormalities range from hypocoagulability and hyperfibrinolysis, resulting in potentially fatal bleeding, in the early stages of trauma to hypercoagulability, leading to widespread clot formation, in the later stages. Pathological changes in the vascular endothelium and its regulation of haemostasis, a phenomenon known as the endotheliopathy of trauma (EoT), are thought to underlie TIC. Our understanding of EoT and its contribution to TIC remains in its infancy largely due to the scarcity of experimental research. This review discusses the mechanisms employed by the vascular endothelium to regulate haemostasis and their dysregulation following traumatic injury before providing an overview of the available experimental in vitro and in vivo models of trauma and their applicability for the study of the EoT and its contribution to TIC.

Platelet factor XIII-A regulates platelet function and promotes clot retraction and stability

Background

Factor XIII (FXIII) is an important proenzyme in the hemostatic system. The plasma-derived enzyme activated FXIII cross-links fibrin fibers within thrombi to increase their mechanical strength and cross-links fibrin to fibrinolytic inhibitors, specifically α2-antiplasmin, to increase resistance to fibrinolysis. We have previously shown that cellular FXIII (factor XIII-A [FXIII-A]), which is abundant in the platelet cytoplasm, is externalized onto the activated membrane and cross-links extracellular substrates. The contribution of cellular FXIII-A to platelet activation and platelet function has not been extensively studied.

Objectives

This study aims to identify the role of platelet FXIII-A in platelet function.

Methods

We used normal healthy platelets with a cell permeable FXIII inhibitor and platelets from FXIII-deficient patients as a FXIII-free platelet model in a range of platelet function and clotting tests.

Results

Our data demonstrate that platelet FXIII-A enhances fibrinogen binding to the platelet surface upon agonist stimulation and improves the binding of platelets to fibrinogen and aggregation under flow in a whole-blood thrombus formation assay. In the absence of FXIII-A, platelets show reduced sensitivity to agonist stimulation, including decreased P-selectin exposure and fibrinogen binding. We show that FXIII-A is involved in platelet spreading where a lack of FXIII-A reduces the ability of platelets to fully spread on fibrinogen and collagen. Our data demonstrate that platelet FXIII-A is important for clot retraction where clots formed in its absence retracted to a lesser extent.

Conclusion

Overall, this study shows that platelet FXIII-A functions during thrombus formation by aiding platelet activation and thrombus retraction in addition to its antifibrinolytic roles.

The CRYOSTAT2 trial: The rationale and study protocol for a multi-Centre, randomised, controlled trial evaluating the effects of early high-dose cryoprecipitate in adult patients with major trauma haemorrhage requiring major haemorrhage protocol activation

OBJECTIVES

To describe the protocol for a multinational randomised, parallel, superiority trial, in which patients were randomised to receive early high-dose cryoprecipitate in addition to standard major haemorrhage protocol (MHP), or Standard MHP alone.

BACKGROUND

Blood transfusion support for trauma-related major bleeding includes red cells, plasma and platelets. The role of concentrated sources of fibrinogen is less clear and has not been evaluated in large clinical trials. Fibrinogen is a key pro-coagulant factor that is essential for stable clot formation. A pilot trial had demonstrated that it was feasible to deliver cryoprecipitate as a source of fibrinogen within 90 min of admission.

METHODS

Randomisation was via opaque sealed envelopes held securely in participating Emergency Departments or transfusion laboratories. Early cryoprecipitate, provided as 3 pools (equivalent to 15 single units of cryoprecipitate or 6 g fibrinogen supplementation), was transfused as rapidly as possible, and started within 90 min of admission. Participants in both arms received standard treatment defined in the receiving hospital MHP. The primary outcome measure was all-cause mortality at 28 days. Symptomatic thrombotic events including venous thromboembolism and arterial thrombotic events (myocardial infarction, stroke) were collected from randomisation up to day 28 or discharge from hospital. EQ5D-5Land Glasgow Outcome Score were completed at discharge and 6 months. All analyses will be performed on an intention to treat basis, with per protocol sensitivity analysis.

RESULTS

The trial opened for recruitment in June 2017 and the final patient completed follow-up in May 2022.

DISCUSSION

This trial will provide firmer evidence to evaluate the effectiveness and cost-effectiveness of early high-dose cryoprecipitate alongside the standard MHP in major traumatic haemorrhage.

The European guideline on management of major bleeding and coagulopathy following trauma: sixth edition

BACKGROUND

Severe trauma represents a major global public health burden and the management of post-traumatic bleeding continues to challenge healthcare systems around the world. Post-traumatic bleeding and associated traumatic coagulopathy remain leading causes of potentially preventable multiorgan failure and death if not diagnosed and managed in an appropriate and timely manner. This sixth edition of the European guideline on the management of major bleeding and coagulopathy following traumatic injury aims to advise clinicians who care for the bleeding trauma patient during the initial diagnostic and therapeutic phases of patient management.

METHODS

The pan-European, multidisciplinary Task Force for Advanced Bleeding Care in Trauma included representatives from six European professional societies and convened to assess and update the previous version of this guideline using a structured, evidence-based consensus approach. Structured literature searches covered the period since the last edition of the guideline, but considered evidence cited previously. The format of this edition has been adjusted to reflect the trend towards concise guideline documents that cite only the highest-quality studies and most relevant literature rather than attempting to provide a comprehensive literature review to accompany each recommendation.

RESULTS

This guideline comprises 39 clinical practice recommendations that follow an approximate temporal path for management of the bleeding trauma patient, with recommendations grouped behind key decision points. While approximately one-third of patients who have experienced severe trauma arrive in hospital in a coagulopathic state, a systematic diagnostic and therapeutic approach has been shown to reduce the number of preventable deaths attributable to traumatic injury.

CONCLUSION

A multidisciplinary approach and adherence to evidence-based guidelines are pillars of best practice in the management of severely injured trauma patients. Further improvement in outcomes will be achieved by optimising and standardising trauma care in line with the available evidence across Europe and beyond.

Acquired haemophilia A diagnosed during pregnancy

Pregnancy-associated haemophilia A is an uncommon, acquired bleeding disorder which usually presents post-partum; very rarely it may present during pregnancy. No consensus guidelines exist on the management of this condition in pregnancy and very few cases have been reported in the literature. Here we describe the case of a woman presenting with acquired haemophilia A during pregnancy and outline the management of her bleeding disorder. We contrast her case with that of two other women, presenting to the same tertiary referral centre, with acquired haemophilia A presenting post-partum. These cases highlight the heterogeneous management of this condition and how it may be successfully managed in pregnancy.

1790 Longitudinal coagulation profiles in patients presenting with acute severe traumatic brain injury (TBI): A prospective observational study

Aims, Objectives and Background

Patients who have sustained a traumatic brain injury (TBI) can have disturbances in coagulation that are distinct from other traumatic bleeding states.1 Coagulopathy is a risk factor for exacerbation of the primary injury, and these patients have less favourable outcomes and increased mortality compared to non-coagulopathic patients.1 Little is known about the longitudinal coagulation changes following TBI.

The aim of this pilot study was to investigate the coagulation profiles of patients presenting with severe TBI over the first 7 days following injury.

Method and Design

Design: Prospective observational study

25 patients presenting to an UK major trauma centre with TBI between August 2021-March 2022 were recruited <24 hours following injury. Professional and family consultee assent was gained and serial blood samples were collected up to three times per day up to day seven.

Coagulation was assessed using thromboelastographs (TEGs) and conventional coagulation tests including Hb, Plt, PT, aPPT and fibrinogen. Pre-hospital, clinical, laboratory and imaging data were collected during the patient admission.

Coagulopathy was defined as having an INR >1.2. The longitudinal changes in the coagulation parameters were plotted for the first seven 7 days and graphically represented. This is a pre-liminary analysis.

Results and Conclusion

25 patients with severe TBI (GCS <12) were recruited. Patients were stratified by their admission INR. 18 patients had an admission INR <1.2 (62% n= 18), and 7 had INR >1.2 (38% n=7). 7 patients who did not have INR >1.2 on their first admission blood test later developed coagulopathy (with an INR >1.2).

Further exploration of the trends seen in conventional coagulation tests and TEG’s over time is required and to understand how these changes correlate to the clinical and imaging findings. The utility of viscoelastic studies such as TEG’s in the assessment of TBI associated coagulopathy remains unclear.

The suboptimal fibrinolytic response in COVID-19 is dictated by high PAI-1

BACKGROUND

Severe COVID-19 disease is associated with thrombotic complications and extensive fibrin deposition. This study investigates whether the hemostatic complications in COVID-19 disease arise due to dysregulation of the fibrinolytic system.

METHODS

This prospective study analyzed fibrinolytic profiles of 113 patients hospitalized with COVID-19 disease with 24 patients with non-COVID-19 respiratory infection and healthy controls. Antigens were quantified by Ella system or ELISA, clot lysis by turbidimetric assay, and plasminogen activator inhibitor-1 (PAI-1)/plasmin activity using chromogenic substrates. Clot structure was visualized by confocal microscopy.

RESULTS

PAI-1 and its cofactor, vitronectin, are significantly elevated in patients with COVID-19 disease compared with those with non-COVID-19 respiratory infection and healthy control groups. Thrombin activatable fibrinolysis inhibitor and tissue plasminogen activator were elevated in patients with COVID-19 disease relative to healthy controls. PAI-1 and tissue plasminogen activator (tPA) were associated with more severe COVID-19 disease severity. Clots formed from COVID-19 plasma demonstrate an altered fibrin network, with attenuated fiber length and increased branching. Functional studies reveal that plasmin generation and clot lysis were markedly attenuated in COVID-19 disease, while PAI-1 activity was elevated. Clot lysis time significantly correlated with PAI-1 levels. Stratification of COVID-19 samples according to PAI-1 levels reveals significantly faster lysis when using the PAI-1 resistant (tPA) variant, tenecteplase, over alteplase lysis.

CONCLUSION

This study shows that the suboptimal fibrinolytic response in COVID-19 disease is directly attributable to elevated levels of PAI-1, which attenuate plasmin generation. These data highlight the important prognostic potential of PAI-1 and the possibility of using pre-existing drugs, such as tenecteplase, to treat COVID-19 disease and potentially other respiratory diseases.

Cryoprecipitate transfusion in trauma patients attenuates hyperfibrinolysis and restores normal clot structure and stability: Results from a laboratory sub-study of the FEISTY trial

BACKGROUND

Fibrinogen is the first coagulation protein to reach critical levels during traumatic haemorrhage. This laboratory study compares paired plasma samples pre- and post-fibrinogen replacement from the Fibrinogen Early In Severe Trauma studY (FEISTY; NCT02745041). FEISTY is the first randomised controlled trial to compare the time to administration of cryoprecipitate (cryo) and fibrinogen concentrate (Fg-C; Riastap) in trauma patients. This study will determine differences in clot strength and fibrinolytic stability within individuals and between treatment arms.

METHODS

Clot lysis, plasmin generation, atomic force microscopy and confocal microscopy were utilised to investigate clot strength and structure in FEISTY patient plasma.

RESULTS

Fibrinogen concentration was significantly increased post-transfusion in both groups. The rate of plasmin generation was reduced 1.5-fold post-transfusion of cryo but remained unchanged with Fg-C transfusion. Plasminogen activator inhibitor 1 activity and antigen levels and Factor XIII antigen were increased post-treatment with cryo, but not Fg-C. Confocal microscopy analysis of fibrin clots revealed that cryo transfusion restored fibrin structure similar to those observed in control clots. In contrast, clots remained porous with stunted fibres after infusion with Fg-C. Cryo but not Fg-C treatment increased individual fibre toughness and stiffness.

CONCLUSIONS

In summary, our data indicate that cryo transfusion restores key fibrinolytic regulators and limits plasmin generation to form stronger clots in an ex vivo laboratory study. This is the first study to investigate differences in clot stability and structure between cryo and Fg-C and demonstrates that the additional factors in cryo allow formation of a stronger and more stable clot.

Gynaecological management of women with inherited bleeding disorders

Women with inherited bleeding disorders (IBDs) may present to healthcare professionals in a variety of ways and commonly will be encountered by either haematology or gynaecology services. Heavy menstrual bleeding is very often the first manifestation of an IBD. There is a wide variation in severity of bleeding for women with IBD and diagnosis and subsequent management of their condition requires multidisciplinary specialised care which is tailored to the individual and includes excellent cross-specialty communication between gynaecology and haematology teams. This guideline is intended for both haematologists and gynaecologists who are involved in the diagnosis and management of women with bleeding disorders. It sets out recommendations about how to investigate heavy menstrual bleeding (HMB), the commonest presentation for women with IBD to hospital services, to guide physicians about how to diagnose an IBD and covers the management of women with known IBD and HMB. The second section sets out recommendations for patients known to have IBD and covers management of patients with IBD in the setting of gynaecological surgery and management for all other non-surgical gynaecological situations.

Platelet transfusion and anticoagulation in hematological cancer-associated thrombosis and thrombocytopenia: The CAVEaT multicenter prospective cohort

BACKGROUND

Venous thromboembolism (VTE) in patients with thrombocytopenia represents a complex management challenge.

OBJECTIVES

To describe practice, document outcomes, and compare management to national guidelines.

METHODS

We present a prospective multicenter cohort of 105 patients with hematological cancer, VTE within 28 days, and platelets <50 × 109 /L from May 14, 2019 to April 24, 2021 from 20 sites.

RESULTS

Median age was 64 and median initial platelet count 28 × 109 /L. Thromboses were: 46% catheter-associated, 11% lower limb, 33% pulmonary emboli (PE), and 10% other sites. Management was according to International Society on Thrombosis and Haemostasis (ISTH) guidance in 30 (47%) of 64 patients with high-risk thrombosis and 2 (5%) of low-risk thrombosis (catheter-associated or asymptomatic subsegmental PE). Twelve patients (11%) received no anticoagulation. At 28 days mortality was 15%, 8% experienced VTE progression, 7% experienced major bleeding, and 25% experienced clinically relevant non-major bleeding. Four inferior vena cava filters were placed, two were later removed. The median number of platelet units transfused was 5 (range 0-53). Twenty-seven percent of patients had a change of management strategy by 28 days. There was no clear relationship among platelet transfusion threshold, anticoagulant dose reduction threshold, and risk of thrombosis progression or major bleeding.

CONCLUSIONS

This data set demonstrates the heterogeneity of approaches used in patients presenting with severe thrombocytopenia and acute thrombosis and confirms the high rates of bleeding in this cohort with thrombosis progression rates similar to the wider cancer-associated thrombosis population. Randomized data is required to inform the optimal management.

A single centre, open label, pilot study evaluating the effect of intra-articular hyaluronic acid injection on pain and functionality when injected into the ankle (tibio-talar and sub-talar) joint in patients with haemophilic arthropathy

AIMS

Ankle arthropathy commonly affects persons with haemophilia (PWH). Joint damage causes loss of movement, pain and reduced function. Current treatments are limited. Viscosupplementation has been used to treat other patient groups with joint damage. Viscosupplements serve to augment or act as a substitute for synovial fluid and may ameliorate the effects of cartilage loss by cushioning joints and reducing pain. This study evaluated intra-articular Ostenil Plus™ (HA) for ankle arthropathy in PWH. Reduction in pain was the primary outcome.

METHODS

A single centre open label pilot study. PWH and significant ankle arthropathy, according to MRI scores, were recruited. Participants received intra-articular HA injections at baseline and 6 months. Follow up assessments were completed three-monthly for 1 year. Pain was assessed by the Visual Analogue Scale (VAS). Participant perceptions of overall changes to pain, function and quality of life were sought.

RESULTS

Twenty-four participants were recruited, three withdrew. Twenty-six joints were injected. Twenty participants had severe haemophilia. Mean age 35 years. Participants reported significant reduction in pain over the study. VAS baseline: 5.62; 6 month 3.92; 12-month 3.42, P < .0001. Joint function improved together with ankle HJHS. No change was seen for EQ-5D-5L. Sixteen participants reported reductions in ankle pain and stiffness and greater confidence in undertaking physical activities. No significant adverse reactions were reported.

CONCLUSION

Ostenil Plus™ treatment improves pain, function and patient perception of functional ability in PWH and ankle arthropathy. This study supports the use of HA as a safe treatment in PWH.

Sex discrimination after injury: is inequity in tranexamic acid administration just the tip of the iceberg?

There is emerging evidence of inequalities in healthcare provision between women and men. Trauma care is no exception with a number of studies indicating lower levels of prioritisation for injured female patients. The antifibrinolytic drug tranexamic acid, reduced trauma deaths to a similar extent in females and males in the international Clinical Randomisation of an Antifibrinolytic in Significant Haemorrhage (CRASH) randomised controlled trials, but in real-world practice, national registry data shows females are less likely to receive tranexamic acid than males. Inequity in the provision of tranexamic acid may extend beyond sex (and gender), and further study is required to examine the effect of age and mechanism of injury differences between men and women in the decision to treat.

Seroprevalence to adeno‐associated virus type 6 in people with hemophilia B from a UK adult cohort

Background

Gene therapy shows promise as a potential “cure” for hemophilia A and B. Adeno‐associated virus (AAV) vectors are the leading platform to deliver modified genetic code of factor VIII or IX to the liver effecting endogenous production. Patient exposure to wild‐type AAV leads to the formation of neutralizing factors, which can prevent successful transduction. It is thus important to establish the seroprevalence of the AAV serotypes in people with hemophilia to aid prediction of successful gene transfer. The seroprevalence of AAV6 in UK people with hemophilia B is not yet reported.

Objectives

We studied the prevalence of anti‐AAV6 neutralizing factors in UK people with hemophilia B (n = 49). We collected data on people’s hepatitis C exposure and treatment with plasma‐derived factor IX (FIX) to identify if there was correlation with AAV6 exposure.

Methods

Serum samples and patient data were collected from 49 people with hemophilia B registered at UK hemophilia comprehensive care centers. The samples were tested for neutralizing factors to AAV6 using a cell‐based transduction inhibition assay.

Results

Thirty‐one percent of patients had serum neutralization against AAV6. There was no correlation between AAV6 seropositivity and previous treatment with plasma‐derived FIX products or hepatitis C exposure.

Conclusion

Based on limited data, there is no evidence of association between the presence of AAV6 neutralizing factors in people with hemophilia B and exposure to contaminated plasma derivatives. The frequency of AAV6 neutralizing factors in our hemophilia B cohort is similar to UK people with hemophilia A and non‐hemophilia populations.

Extended Coagulation Profiling in Isolated Traumatic Brain Injury: A CENTER-TBI Analysis

BACKGROUND

Trauma-induced coagulopathy in traumatic brain injury (TBI) remains associated with high rates of complications, unfavorable outcomes, and mortality. The underlying mechanisms are largely unknown. Embedded in the prospective multinational Collaborative European Neurotrauma Effectiveness Research in Traumatic Brain Injury (CENTER-TBI) study, coagulation profiles beyond standard conventional coagulation assays were assessed in patients with isolated TBI within the very early hours of injury.

METHODS

Results from blood samples (citrate/EDTA) obtained on hospital admission were matched with clinical and routine laboratory data of patients with TBI captured in the CENTER-TBI central database. To minimize confounding factors, patients with strictly isolated TBI (iTBI) (n = 88) were selected and stratified for coagulopathy by routine international normalized ratio (INR): (1) INR < 1.2 and (2) INR ≥ 1.2. An INR > 1.2 has been well adopted over time as a threshold to define trauma-related coagulopathy in general trauma populations. The following parameters were evaluated: quick's value, activated partial thromboplastin time, fibrinogen, thrombin time, antithrombin, coagulation factor activity of factors V, VIII, IX, and XIII, protein C and S, plasminogen, D-dimer, fibrinolysis-regulating parameters (thrombin activatable fibrinolysis inhibitor, plasminogen activator inhibitor 1, antiplasmin), thrombin generation, and fibrin monomers.

RESULTS

Patients with iTBI with INR ≥ 1.2 (n = 16) had a high incidence of progressive intracranial hemorrhage associated with increased mortality and unfavorable outcome compared with patients with INR < 1.2 (n = 72). Activity of coagulation factors V, VIII, IX, and XIII dropped on average by 15-20% between the groups whereas protein C and S levels dropped by 20%. With an elevated INR, thrombin generation decreased, as reflected by lower peak height and endogenous thrombin potential (ETP), whereas the amount of fibrin monomers increased. Plasminogen activity significantly decreased from 89% in patients with INR < 1.2 to 76% in patients with INR ≥ 1.2. Moreover, D-dimer levels significantly increased from a mean of 943 mg/L in patients with INR < 1.2 to 1,301 mg/L in patients with INR ≥ 1.2.

CONCLUSIONS

This more in-depth analysis beyond routine conventional coagulation assays suggests a counterbalanced regulation of coagulation and fibrinolysis in patients with iTBI with hemostatic abnormalities. We observed distinct patterns involving key pathways of the highly complex and dynamic coagulation system that offer windows of opportunity for further research. Whether the changes observed on factor levels may be relevant and explain the worse outcome or the more severe brain injuries by themselves remains speculative.

Neurocognitive correlates of probable posttraumatic stress disorder following traumatic brain injury

Introduction

Neurocognitive problems associated with posttraumatic stress disorder (PTSD) can interact with impairment resulting from traumatic brain injury (TBI).

Research question

We aimed to identify neurocognitive problems associated with probable PTSD following TBI in a civilian sample.

Material and methods

The study is part of the CENTER-TBI project (Collaborative European Neurotrauma Effectiveness Research) that aims to better characterize TBI. For this cross-sectional study, we included patients of all severities aged over 15, and a Glasgow Outcome Score Extended (GOSE) above 3. Participants were assessed at six months post-injury on the PTSD Checklist-5 (PCL-5), the Trail Making Test (TMT), the Rey Auditory Verbal Learning Test (RAVLT) and the Cambridge Neuropsychological Test Automated Battery (CANTAB). Primary analysis was a complete case analysis. Regression analyses were performed to investigate the association between the PCL-5 and cognition.

Results

Of the 1134 participants included in the complete case analysis, 13.5% screened positive for PTSD. Probable PTSD was significantly associated with higher TMT-(B-A) (OR ​= ​1.35, 95% CI: 1.14–1.60, p ​< ​.001) and lower RAVLT-delayed recall scores (OR ​= ​0.74, 95% CI: 0.61–0.91, p ​= ​.004) after controlling for age, sex, psychiatric history, baseline Glasgow Coma Scale and education.

Discussion and conclusion

Poorer performance on cognitive tests assessing task switching and, to a lesser extent, delayed verbal recall is associated with probable PTSD in civilians who have suffered TBI.

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Six months after traumatic brain injury 13.5% of people screen positive for PTSD.

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Task switching performance and verbal memory are related to probable PTSD.

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PTSD severity is related to processing speed and task switching performance.

Fibrinogen Replacement in Haemostatic Resuscitation: Dose, Laboratory Targets and Product Choice

Fibrinogen is a key coagulation protein that is necessary for the formation of stable clots. Fibrinogen levels have been reported to be one of the first to fall during major haemorrhage reflecting consumption, dilution and fibrinogenolysis. Its role in acquired major haemorrhage, both in relation to the contribution it plays to the coagulopathy of major bleeding that can exacerbate bleeding and how effective fibrinogen supplementation can be at improving clinical outcomes, has received a great deal of attention over the last 10 - 15 years. This commentary focuses on just three of the more recent publications from the last 5 years that provide some of the evidence behind how we can think about fibrinogen as a haemostatic treatment for acquired major haemorrhage and how we can use the laboratory thresholds to guide therapy.

Non-invasive diagnosis of deep vein thrombosis from ultrasound imaging with machine learning

Deep vein thrombosis (DVT) is a blood clot most commonly found in the leg, which can lead to fatal pulmonary embolism (PE). Compression ultrasound of the legs is the diagnostic gold standard, leading to a definitive diagnosis. However, many patients with possible symptoms are not found to have a DVT, resulting in long referral waiting times for patients and a large clinical burden for specialists. Thus, diagnosis at the point of care by non-specialists is desired. We collect images in a pre-clinical study and investigate a deep learning approach for the automatic interpretation of compression ultrasound images. Our method provides guidance for free-hand ultrasound and aids non-specialists in detecting DVT. We train a deep learning algorithm on ultrasound videos from 255 volunteers and evaluate on a sample size of 53 prospectively enrolled patients from an NHS DVT diagnostic clinic and 30 prospectively enrolled patients from a German DVT clinic. Algorithmic DVT diagnosis performance results in a sensitivity within a 95% CI range of (0.82, 0.94), specificity of (0.70, 0.82), a positive predictive value of (0.65, 0.89), and a negative predictive value of (0.99, 1.00) when compared to the clinical gold standard. To assess the potential benefits of this technology in healthcare we evaluate the entire clinical DVT decision algorithm and provide cost analysis when integrating our approach into diagnostic pathways for DVT. Our approach is estimated to generate a positive net monetary benefit at costs up to £72 to £175 per software-supported examination, assuming a willingness to pay of £20,000/QALY.

Survey evaluating clinical equipoise around platelet transfusion after head injury and traumatic intracranial haemorrhage (ICH) in patients on antiplatelet medications

INTRODUCTION

Patients aged 60 or over account for over half of the severely injured trauma patients and a traumatic brain injury is the most common injury sustained. Many of these patients are taking antiplatelet medications but there is clinical equipoise about the role of platelet transfusion in patients with traumatic intracranial haemorrhage (ICH) taking prior antiplatelet medications.

METHOD

A prepiloted survey was designed to explore a range of clinical issues in managing patients taking antiplatelet medications admitted with a traumatic brain injury. This was sent via email to consultants and specialty registrar members of a variety of relevant UK societies and working groups in the fields of emergency medicine, critical care, neurosurgery and haematology.

RESULTS

193 responses were received, mostly from colleagues in emergency medicine, neurosurgery, anaesthesia and haematology. Respondents indicated that there is a lack of evidence to support the use of platelet transfusion in this patient population but also lack of evidence of harm. Results also demonstrate uncertainties as to whether platelets should be given to all or some patients and doubt regarding the value of viscoelastic testing.

DISCUSSION

Our survey demonstrates equipoise in current practice with regards to platelet transfusion in patients with a traumatic ICH who are taking antiplatelet medication. There is support for additional trials to investigate the effect of platelet transfusion in this rising population of older, high-risk patients, in order to provide a better evidence-base for guideline development.

Factor VIII levels and bleeding according to factor 8 (F8) mutation in pregnant carriers of haemophilia A: a multicentre retrospective cohort study

This retrospective cohort study investigated the association between factor 8 (F8) genotype severity and factor VIII (FVIII) levels during pregnancy for 52 women (64 pregnancies) who were heterozygous carriers of mild, moderate or severe haemophilia A. There were no significant differences in FVIII levels for carriers of mild, moderate or severe haemophilia A at baseline [mean (SD) level: mild, 0·78 (0·22); moderate, 0·83 (0·33); severe, 0·70 (0·25) iu/ml; P = 0·81] or in the third trimester [mean (SD) level: mild, 1·42 (0·28); moderate, 1·47 (0·41); severe, 1·37 (0·49) iu/ml; P = 0·80). Post-partum haemorrhage rates were higher for carriers of severe haemophilia A (13/24; 54·2%) compared to carriers of mild haemophilia A (four of 14; 28·6%).

Fibrinogen Replacement Therapy for Traumatic Coagulopathy: Does the Fibrinogen Source Matter?

Fibrinogen is the first coagulation protein to reach critically low levels during traumatic haemorrhage. There have been no differential effects on clinical outcomes between the two main sources of fibrinogen replacement: cryoprecipitate and fibrinogen concentrate (Fg-C). However, the constituents of these sources are very different. The aim of this study was to determine whether these give rise to any differences in clot stability that may occur during trauma haemorrhage. Fibrinogen deficient plasma (FDP) was spiked with fibrinogen from cryoprecipitate or Fg-C. A panel of coagulation factors, rotational thromboelastography (ROTEM), thrombin generation (TG), clot lysis and confocal microscopy were performed to measure clot strength and stability. Increasing concentrations of fibrinogen from Fg-C or cryoprecipitate added to FDP strongly correlated with Clauss fibrinogen, demonstrating good recovery of fibrinogen (r² = 0.99). A marked increase in Factor VIII, XIII and α₂-antiplasmin was observed in cryoprecipitate (p < 0.05). Increasing concentrations of fibrinogen from both sources were strongly correlated with ROTEM parameters (r² = 0.78-0.98). Cryoprecipitate therapy improved TG potential, increased fibrinolytic resistance and formed more homogeneous fibrin clots, compared to Fg-C. In summary, our data indicate that cryoprecipitate may be a superior source of fibrinogen to successfully control bleeding in trauma coagulopathy. However, these different products require evaluation in a clinical setting.

Viscoelastic haemostatic assay augmented protocols for major trauma haemorrhage (ITACTIC): a randomized, controlled trial

PURPOSE

Contemporary trauma resuscitation prioritizes control of bleeding and uses major haemorrhage protocols (MHPs) to prevent and treat coagulopathy. We aimed to determine whether augmenting MHPs with Viscoelastic Haemostatic Assays (VHA) would improve outcomes compared to Conventional Coagulation Tests (CCTs).

METHODS

This was a multi-centre, randomized controlled trial comparing outcomes in trauma patients who received empiric MHPs, augmented by either VHA or CCT-guided interventions. Primary outcome was the proportion of subjects who, at 24 h after injury, were alive and free of massive transfusion (10 or more red cell transfusions). Secondary outcomes included 28-day mortality. Pre-specified subgroups included patients with severe traumatic brain injury (TBI).

RESULTS

Of 396 patients in the intention to treat analysis, 201 were allocated to VHA and 195 to CCT-guided therapy. At 24 h, there was no difference in the proportion of patients who were alive and free of massive transfusion (VHA: 67%, CCT: 64%, OR 1.15, 95% CI 0.76-1.73). 28-day mortality was not different overall (VHA: 25%, CCT: 28%, OR 0.84, 95% CI 0.54-1.31), nor were there differences in other secondary outcomes or serious adverse events. In pre-specified subgroups, there were no differences in primary outcomes. In the pre-specified subgroup of 74 patients with TBI, 64% were alive and free of massive transfusion at 24 h compared to 46% in the CCT arm (OR 2.12, 95% CI 0.84-5.34).

CONCLUSION

There was no difference in overall outcomes between VHA- and CCT-augmented-major haemorrhage protocols.

Incidence of symptomatic, image-confirmed venous thromboembolism following hospitalization for COVID-19 with 90-day follow-up

Although COVID-19 has been reported to be associated with high rates of venous thromboembolism (VTE), the risk of VTE and bleeding after hospitalization for COVID-19 remains unclear, and the optimal hospital VTE prevention strategy is not known. We collected retrospective observational data on thrombosis and bleeding in 303 consecutive adult patients admitted to the hospital for at least 24 hours for COVID-19. Patients presenting with VTE on admission were excluded. Data were collected until 90 days after admission or known death by using medical records and an established national VTE network. Maximal level of care was ward based in 78% of patients, with 22% requiring higher dependency care (12% noninvasive ventilation, 10% invasive ventilation). Almost all patients (97.0%) received standard thromboprophylaxis or were already receiving therapeutic anticoagulation (17.5%). Symptomatic image-confirmed VTE occurred in 5.9% of patients during index hospitalization, and in 7.2% at 90 days after admission (23.9% in patients requiring higher dependency care); half the events were isolated segmental or subsegmental defects on lung imaging. Bleeding occurred in 13 patients (4.3%) during index hospitalization (1.3% had major bleeding). The majority of bleeds occurred in patients on the general ward, and 6 patients were receiving treatment-dose anticoagulation, highlighting the need for caution in intensifying standard thromboprophylaxis strategies. Of 152 patients discharged from the hospital without an indication for anticoagulation, 97% did not receive thromboprophylaxis after discharge, and 3% received 7 days of treatment with low molecular weight heparin after discharge. The rate of symptomatic VTE in this group at 42 days after discharge was 2.6%, highlighting the need for large prospective randomized controlled trials of extended thromboprophylaxis after discharge in COVID-19.

Global Characterisation of Coagulopathy in Isolated Traumatic Brain Injury (iTBI): A CENTER-TBI Analysis

BACKGROUND

Trauma-induced coagulopathy in patients with traumatic brain injury (TBI) is associated with high rates of complications, unfavourable outcomes and mortality. The mechanism of the development of TBI-associated coagulopathy is poorly understood.

METHODS

This analysis, embedded in the prospective, multi-centred, observational Collaborative European NeuroTrauma Effectiveness Research in Traumatic Brain Injury (CENTER-TBI) study, aimed to characterise the coagulopathy of TBI. Emphasis was placed on the acute phase following TBI, primary on subgroups of patients with abnormal coagulation profile within 4 h of admission, and the impact of pre-injury anticoagulant and/or antiplatelet therapy. In order to minimise confounding factors, patients with isolated TBI (iTBI) (n = 598) were selected for this analysis.

RESULTS

Haemostatic disorders were observed in approximately 20% of iTBI patients. In a subgroup analysis, patients with pre-injury anticoagulant and/or antiplatelet therapy had a twice exacerbated coagulation profile as likely as those without premedication. This was in turn associated with increased rates of mortality and unfavourable outcome post-injury. A multivariate analysis of iTBI patients without pre-injury anticoagulant therapy identified several independent risk factors for coagulopathy which were present at hospital admission. Glasgow Coma Scale (GCS) less than or equal to 8, base excess (BE) less than or equal to - 6, hypothermia and hypotension increased risk significantly.

CONCLUSION

Consideration of these factors enables early prediction and risk stratification of acute coagulopathy after TBI, thus guiding clinical management.

Characterisation of a novel thrombomodulin c.1487delC,p.(Pro496Argfs*10) variant and evaluation of therapeutic strategies to manage the rare bleeding phenotype

INTRODUCTION

A novel variant in the thrombomodulin (TM) gene, c.1487delC,p.(Pro496Argfs*10), referred to as Pro496Argfs*10, was identified in a family with an unexplained bleeding disorder. The Pro496Argfs*10 variant results in loss of the transmembrane and intracellular segments of TM and is associated with an increase in soluble TM (sTM) in the plasma. The aim of this study was to characterise the effect of elevated sTM on thrombin generation (TG) and fibrinolysis, and to evaluate therapeutic strategies to manage the patients.

METHODS

Plasma samples were obtained from two patients carrying the variant. TG was triggered using 5 pM tissue factor and measured using the Calibrated Automated Thrombogram. A turbidity clot lysis assay was used to monitor fibrinolysis. TM antigen was quantified by ELISA.

RESULTS

Patients with the Pro496Argfs*10 variant had significantly elevated plasma sTM compared to controls (372.6 vs. 6.0 ng/ml). TG potential was significantly lower in patients but was restored by inhibition of activated protein C (APC) or addition of activated Factor VII (FVIIa) or platelet concentrates. In vitro experiments suggested that activated prothrombin complex concentrates (APCC) posed a risk of thrombosis. The time to 50% lysis was significantly prolonged in patients compared to controls, 69.7 vs. 42.3 min. Clot lysis time was shortened by inhibition of activated thrombin activatable fibrinolysis inhibitor (TAFIa).

CONCLUSIONS

Our data demonstrate that increased sTM enhances APC generation and reduces TG. Simultaneously, the rate of fibrinolysis is delayed due to increased TAFI activation by sTM. Treatment with platelet or FVIIa concentrates may be beneficial to manage this rare bleeding disorder.

Thrombotic and haemorrhagic complications in critically ill patients with COVID-19: a multicentre observational study

BACKGROUND

Optimal prophylactic and therapeutic management of thromboembolic disease in patients with COVID-19 remains a major challenge for clinicians. The aim of this study was to define the incidence of thrombotic and haemorrhagic complications in critically ill patients with COVID-19. In addition, we sought to characterise coagulation profiles using thromboelastography and explore possible biological differences between patients with and without thrombotic complications.

METHODS

We conducted a multicentre retrospective observational study evaluating all the COVID-19 patients received in four intensive care units (ICUs) of four tertiary hospitals in the UK between March 15, 2020, and May 05, 2020. Clinical characteristics, laboratory data, thromboelastography profiles and clinical outcome data were evaluated between patients with and without thrombotic complications.

RESULTS

A total of 187 patients were included. Their median (interquartile (IQR)) age was 57 (49-64) years and 124 (66.3%) patients were male. Eighty-one (43.3%) patients experienced one or more clinically relevant thrombotic complications, which were mainly pulmonary emboli (n = 42 (22.5%)). Arterial embolic complications were reported in 25 (13.3%) patients. ICU length of stay was longer in patients with thrombotic complications when compared with those without. Fifteen (8.0%) patients experienced haemorrhagic complications, of which nine (4.8%) were classified as major bleeding. Thromboelastography demonstrated a hypercoagulable profile in patients tested but lacked discriminatory value between those with and without thrombotic complications. Patients who experienced thrombotic complications had higher D-dimer, ferritin, troponin and white cell count levels at ICU admission compared with those that did not.

CONCLUSION

Critically ill patients with COVID-19 experience high rates of venous and arterial thrombotic complications. The rates of bleeding may be higher than previously reported and re-iterate the need for randomised trials to better understand the risk-benefit ratio of different anticoagulation strategies.

Long-term safety and efficacy of N8-GP in previously treated adults and adolescents with hemophilia A: Final results from pathfinder2

BACKGROUND

N8-GP (turoctocog alfa pegol; Esperoct® , Novo Nordisk A/S, Bagsvaerd, Denmark) is a glycoPEGylated human recombinant factor VIII with a half-life of ~1.6-fold of standard FVIII products. pathfinder2 (NCT01480180) was a multi-national, open-label trial of N8-GP in previously treated adolescent and adult patients with severe hemophilia A.

OBJECTIVE

We report end-of-trial efficacy and safety of N8-GP from pathfinder2.

METHODS

pathfinder2 main phase and extension phase part 1 results have been previously reported. During extension phase part 2, patients could switch from N8-GP prophylaxis 50 IU/kg every fourth day (Q4D) or 75 IU/kg once weekly (Q7D), depending on bleeding status. Extension phase part 2 collected long-term safety and efficacy data for all regimens until trial end (first patient in main phase, 30 January 2012; trial end, 10 December 2018).

RESULTS

Overall, 186 patients were exposed to N8-GP for up to 6.6 years (median 5.4 years). The estimated annualized bleeding rate (ABR) was 2.14 (median 0.84) for the Q4D prophylaxis arm and 1.31 (median 1.67) for the Q7D prophylaxis arm. Nearly 30% of patients experienced zero bleeds throughout the entire duration of the trial, the hemostatic response was 83.2% across all treatment arms, and patient-reported outcomes were maintained or slightly improved. No safety concerns were detected.

CONCLUSION

Data from the completed pathfinder2 trial, one of the largest and longest-running clinical trials to investigate treatment of severe hemophilia A, demonstrate the efficacy and safety of N8-GP in previously treated adolescent and adult patients.

Coagulation status of critically ill patients with and without liver disease assessed using a novel thrombin generation analyzer

The liver synthesizes the majority of pro- and anti-coagulant and fibrinolytic proteins, and during liver dysfunction synthesis of these proteins is reduced. The end point of conventional hemostatic tests, such as the prothrombin time (PT), occurs when only 5% of thrombin generation (TG) has taken place and is not sensitive to the effects of natural anti-coagulants. The aim of this study was to determine whether TG in the presence of thrombomodulin (TM) provides more useful information about coagulation potential, in comparison to the PT. Analysis was performed on ST Genesia, a novel TG analyzer from Diagnostica Stago. TG was measured using STG-Thromboscreen, a reagent containing an intermediate concentration of human tissue factor (TF) ± rabbit TM to account for anti-coagulant protein C (PC) activity. Platelet-poor plasma (PPP) samples were from the Intensive Care Study of Coagulopathy-2 (ISOC-2), which recruited patients admitted to critical care with a prolonged PT (3 seconds above the reference range). Despite a prolonged PT, 48.0% and 60.7% of patients in the liver and non-liver groups had TG parameters within the normal range. Addition of TM reduced TG by 34.5% and 41.8% in the liver and non-liver groups, respectively. Interestingly, fresh frozen plasma (FFP) transfusion had no impact on TG. Measurement of TG with addition of TM provides a more informative assessment of coagulation capacity and indicates that hemostasis is balanced in patients with liver disease during critical illness, despite conventional tests suggesting that bleeding risk is increased.

A Novel, Enriched Population Pharmacokinetic Model for Recombinant Factor VIII-Fc Fusion Protein Concentrate in Hemophilia A Patients

Background The currently published population pharmacokinetic (PK) models used for PK-guided dosing in hemophilia patients are based on clinical trial data and usually not externally validated in clinical practice. The aim of this study was to validate a published model for recombinant factor VIII-Fc fusion protein (rFVIII-Fc) concentrate and to develop an enriched model using independently collected clinical data if required.

Methods Clinical data from hemophilia A patients treated with rFVIII-Fc concentrate (Elocta) participating in the United Kingdom Extended Half-Life Outcomes Registry were collected. The predictive performance of the published model was assessed using mean percentage error (bias) and mean absolute percentage error (inaccuracy). An extended population PK model was developed using nonlinear mixed-effects modeling (NONMEM).

Results A total of 43 hemophilia A patients (FVIII ≤ 2 IU/dL), aged 5 to 70 years, were included. The prior model was able to predict the collected 244 rFVIII-Fc levels without significant bias (–1.0%, 95% CI: –9.4 to 7.3%) and with acceptable accuracy (12.9%). However, clearance and central distribution volume were under predicted in patients <12 years, which was expected as this age group was not represented in the previous model population. An enriched population PK model was constructed, which was able to successfully characterize PK profiles of younger children.

Conclusion We concluded that the existing rFVIII-Fc population PK model is valid for patients ≥ 12 years. However, it is not reliable in younger patients. Our alternative model, constructed from real world patient data including children, allows for better description of patients ≥5 years.

The application of a haemorrhage assessment tool in evaluating control of bleeding in a pilot trauma haemorrhage trial

OBJECTIVES

To determine whether it was feasible to use a haemorrhage assessment tool (HAT) within a trauma trial and whether the data obtained could differentiate patients who had achieved haemostasis.

BACKGROUND

Major haemorrhage is one of the leading causes of death worldwide, affecting 40% of trauma patients. Clinical trials evaluating haemostatic interventions often use transfusion outcomes as a primary endpoint. Transfusion is highly dependent on local practice, limiting its reliability as a robust, transferable endpoint.

METHODS

A five-point HAT questionnaire was applied to participants enrolled into the EFIT-1 trial. This RCT evaluated the feasibility of administering a 6 g fibrinogen concentrate to patients with severe trauma haemorrhage.

RESULTS

Of participants, 98% completed a HAT; 75% participants had 'achieved haemostasis' at the time of tool completion, as determined by clinical acumen alone. HAT scores were able to differentiate which participants required transfusion after 3 h. Of participants, 56% were transfused red blood cells when they scored 0-2, compared to 17% with HAT scores between 3 and 5.

CONCLUSION

This study has confirmed the feasibility of using a HAT during the emergency care of patients suffering trauma haemorrhage, and future studies should be conducted to determine its value as an endpoint in haemostasis studies.

Next-generation sequencing for the diagnosis of MYH9-RD: Predicting pathogenic variants

The heterogeneous manifestations of MYH9‐related disorder (MYH9‐RD), characterized by macrothrombocytopenia, Döhle‐like inclusion bodies in leukocytes, bleeding of variable severity with, in some cases, ear, eye, kidney, and liver involvement, make the diagnosis for these patients still challenging in clinical practice. We collected phenotypic data and analyzed the genetic variants in more than 3,000 patients with a bleeding or platelet disorder. Patients were enrolled in the BRIDGE‐BPD and ThromboGenomics Projects and their samples processed by high throughput sequencing (HTS). We identified 50 patients with a rare variant in MYH9. All patients had macrothrombocytes and all except two had thrombocytopenia. Some degree of bleeding diathesis was reported in 41 of the 50 patients. Eleven patients presented hearing impairment, three renal failure and two elevated liver enzymes. Among the 28 rare variants identified in MYH9, 12 were novel. HTS was instrumental in diagnosing 23 patients (46%). Our results confirm the clinical heterogeneity of MYH9‐RD and show that, in the presence of an unclassified platelet disorder with macrothrombocytes, MYH9‐RD should always be considered. A HTS‐based strategy is a reliable method to reach a conclusive diagnosis of MYH9‐RD in clinical practice.

Surgery in Traumatic Injury and Perioperative Considerations

A severely injured patient presents several unique challenges to an admitting trauma team. Not only must the extent of the patient's injuries, particularly those that are life-threatening, be determined within minutes of hospital arrival, but also the trauma team needs to be able to assess whether the patient is bleeding and/or has an attendant coagulopathy. Early management of trauma patients is dictated by the presence (or absence) of significant bleeding. Standard definitive surgical procedures can be conducted in hemodynamically stable patients, but those in hemorrhagic shock should be treated according to damage control resuscitation (DCR) principles. DCR is a practice that has evolved over the last two to three decades, combining limited surgical techniques, which provide early hemorrhage control, and balanced transfusion resuscitation strategies, which mitigate (and ideally) treat trauma-induced coagulopathy (TIC). This review describes the contemporary perioperative management of trauma patients who have significant bleeding and/or TIC and sets out the evidence around the current approach for hemostatic resuscitation in these patients.

Adenovirus-associated antibodies in UK cohort of hemophilia patients: A seroprevalence study of the presence of adenovirus-associated virus vector-serotypes AAV5 and AAV8 neutralizing activity and antibodies in patients with hemophilia A

BACKGROUND

Current treatment for severe hemophilia A is replacement of deficient factor. Although replacement therapy has improved life expectancy and quality, limitations include frequent infusions and high costs. Gene therapy is a potential alternative that utilizes an adeno-associated virus (AAV) vector containing the human genetic code for factor 8 (FVIII) that transduces the liver, enabling endogenous production of FVIII. Individuals with preexisting immunity to AAV serotypes may be less likely to benefit from this treatment.

OBJECTIVES

This study measured seroprevalence of antibodies to AAV5 and 8 in an UK adult hemophilia A cohort.

PATIENTS/METHODS

Patients were recruited from seven hemophilia centres in the UK. Citrated plasma samples from 100 patients were tested for preexisting activities against AAV5 and 8 using AAV transduction inhibition and total antibodies assays.

RESULTS

Twent-one percent of patients had antibodies against AAV5 and 23% had antibodies against AAV8. Twenty-five percent and 38% of patients exhibited inhibitors of AAV5 or AAV8 cellular transduction respectively. Overall seroprevalence using either assay against AAV5 was 30% and against AAV8 was 40% in this cohort of hemophilia A patients. Seropositivity for both AAV5 and AAV8 was seen in 24% of participants.

CONCLUSIONS

Screening for preexisting immunity may be important in identifying patients most likely to benefit from gene therapy. Clinical studies may be needed to evaluate the impact of preexisting immunity on the safety and efficacy of AAV mediated gene therapy.