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.

Desmopressin for patients with spontaneous intracerebral haemorrhage taking antiplatelet drugs (DASH): a UK-based, phase 2, randomised, placebo-controlled, multicentre feasibility trial.

BACKGROUND: The risk of death from spontaneous intracerebral haemorrhage is increased for people taking antiplatelet drugs. We aimed to assess the feasibility of randomising patients on antiplatelet drug therapy with spontaneous intracerebral haemorrhage to desmopressin or placebo to reduce the antiplatelet drug effect. METHODS: DASH was a phase 2, randomised, placebo-controlled, multicentre feasibility trial. Patients were recruited from ten acute stroke centres in the UK and were eligible if they had an intracerebral haemorrhage with stroke symptom onset within 24 h of randomisation, were aged 18 years or older, and were taking an antiplatelet drug. Participants were randomly assigned (1:1) to a single dose of intravenous desmopressin 20 µg or matching placebo. Treatment allocation was concealed from all staff and patients involved in the trial. The primary outcome was feasibility, which was measured as the number of eligible patients randomised and the proportion of eligible patients approached, and analysis was by intention to treat. The trial was prospectively registered with ISRCTN (reference ISRCTN67038373), and it is closed to recruitment. FINDINGS: Between April 1, 2019, and March 31, 2022, 1380 potential participants were screened for eligibility. 176 (13%) participants were potentially eligible, of whom 57 (32%) were approached, and 54 (31%) consented and were subsequently recruited and randomly assigned to receive desmopressin (n=27) or placebo (n=27). The main reason for eligible patients not being recruited was the patient arriving out of hours (74 [61%] of 122 participants). The recruitment rate increased after the enrolment period was extended from 12 h to 24 h, but it was then impaired due to the COVID-19 pandemic. Of the 54 participants included in the analysis (mean age 76·4 years [SD 11·3]), most were male (36 [67%]) and White (50 [93%]). 53 (98%) of 54 participants received all of their allocated treatment (one participant assigned desmopressin only received part of the infusion). No participants were lost to follow-up or withdrew from the trial. Death or dependency on others for daily activities at day 90 (modified Rankin Scale score >4) occurred in six (22%) of 27 participants in the desmopressin group and ten (37%) of 27 participants in the placebo group. Serious adverse events occurred in 12 (44%) participants in the desmopressin group and 13 (48%) participants in the placebo group. The most common adverse events were expansion of the haemorrhagic stroke (four [15%] of 27 participants in the desmopressin group and six [22%] of 27 participants in the placebo group) and pneumonia (one [4%] of 27 participants in the desmopressin group and six [22%] of 27 participants in the placebo group). INTERPRETATION: Our results show it is feasible to randomise patients with spontaneous intracerebral haemorrhage who are taking antiplatelet drugs to desmopressin or placebo. Our findings support the need for a definitive trial to determine if desmopressin improves outcomes in patients with intracerebral haemorrhage on antiplatelet drug therapy. FUNDING: National Institute for Health Research.

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.

Real world reduction in red cell transfusion with restrictive transfusion threshold in haematology inpatients.

OBJECTIVES: The aim of this study was to assess the reduction in red cell transfusions following a change in the red cell transfusion threshold for haematology inpatients from 80 to 70 g/L. BACKGROUND: Haematology patients are among the high users of red blood cells. We reduced the threshold for transfusion of haematology inpatients to 70 g/L. This was based on evidence provided by randomised controlled trial published in 2020 that showed restrictive transfusion is non-inferior to liberal transfusion. METHOD: We assessed red cell transfusions for haematology inpatients at Oxford University Hospitals NHS Foundation Trust for 9 months before and 9 months after a change in red cell transfusion threshold from 80 to 70 g/L. RESULTS: After the change in threshold to 70 g/L or less from 80 g/L, the median number of red cell transfusions per month reduced to 88 from 111. This was a 23% reduction in the total number of red cells administered per month. CONCLUSION: These results show the real-world reductions in transfusion that can be made by putting local transfusion guidelines in line with the international recommendations. This is of particular importance at a time of national blood shortage.

Drug-induced thrombotic thrombocytopenic purpura: A systematic review and review of European and North American pharmacovigilance data.

Many medications have been reported to be associated with thrombotic thrombocytopenic purpura (TTP) through pharmacovigilance data and published case reports. Whilst there are existing data available regarding drug-induced thrombotic microangiopathy, there is no available synthesis of evidence to assess drug-induced TTP (DI-TTP). Despite this lack of evidence, patients with TTP are often advised against using many medications due to the theoretical risk of DI-TTP. This systematic review evaluated the evidence for an association of medications reported as potential triggers for TTP. Of 5098 records available 261 articles were assessed further for eligibility. Fifty-seven reports, totalling 90 patients, were included in the final analysis. There were no cases where the level of association was rated as definite or probable, demonstrating a lack of evidence of any drug causing DI-TTP. This paucity of evidence was also demonstrated in the pharmacovigilance data, where 613 drugs were reported as potential causes of TTP without assessment of the strength of association. This systematic review demonstrates the need for standardised reporting of potential drugs causing TTP. Many reports omit basic information and, therefore, hinder the chance of finding a causative link if one exists.

Intraoperative cell salvage using swab wash and serial thromboelastography in elective abdominal aortic aneurysm surgery involving massive blood loss.

The loss of 50% blood volume is one accepted definition of massive haemorrhage, which ordinarily would trigger the massive transfusion protocol, involving the administration of high ratios of fresh frozen plasma and platelets to allogeneic red cells. We investigated 53 patients who experienced >50% blood loss during open elective abdominal aortic aneurysm surgery to assess allogeneic blood component usage and coagulopathy. Specialist patient blood management practitioners used a tailored cell salvage technique including swab wash to maximise blood return. We assessed the proportion of patients who did not require allogeneic blood components and develop evidence of coagulopathy by thromboelastography (TEG) parameters. Blood loss was 50%-174% (mean [SD] 68% [27%]) of blood volume. The mean (SD) intraoperative decrease in haemoglobin concentration, assessed by arterial blood gas analysis, was 5 (13) g/l. No patient received allogeneic red cells intraoperatively. Four of the 53 (8%) patients received blood components in the first 24 h postoperatively at the anaesthetists' discretion. No patient had intraoperative TEG changes indicative of fibrinolysis or coagulopathy. The 30-day mortality was 2% (one of 53). Reduction of allogeneic transfusion is one aim of patient blood management techniques. We have demonstrated virtual avoidance of allogeneic blood product transfusion despite massive blood loss. These data show possible alternatives to the current massive transfusion protocols to the management of elective vascular surgical patients.

Outcomes and management of pregnancy in women with bleeding disorder of unknown cause.

BACKGROUND: Patients with a bleeding tendency with normal laboratory tests have been described as having an unclassified bleeding disorder or bleeding disorder of unknown cause (BDUC). There are very little data available on how to manage pregnancy. OBJECTIVES: To study management and outcomes of these patients at four United Kingdom hemophilia comprehensive care centers. METHODS: Retrospective case note review from 2010-2020. RESULTS: Sixty deliveries in 36 patients were recorded. The median International Society on Thrombosis and Haemostasis bleeding assessment tool score was 9. In 54 cases for which data were available, the odds ratio for post partum hemorrhage (PPH) was 6.3 for no primary hemostatic prophylaxis versus prophylaxis (95% confidence interval 1.2-34.2, p < .05); 7/9 (78%) versus 16/45 (36%) PPH incidence for the groups, respectively. Hemostatic prophylaxis was with tranexamic acid but some patients received desmopressin or platelet infusions. Secondary PPH was seen in 5/60 (8%) of cases. No neonatal bleeding complications or maternal thromboembolic complications were noted. Avoidance of regional anesthesia and fetal delivery precautions were commonly advised, but in the small number of cases in which they occurred no complications were noted. CONCLUSIONS: Despite hemostatic prophylaxis PPH was commonly seen. Further prospective studies of BDUC patients are required to determine optimal management in pregnancy as well as determine the pathophysiological basis of bleeding.

Management of surgery, menorrhagia and child-birth for patients with unclassified bleeding disorders: a systematic review of cohort studies.

Unclassified bleeding disorders account for 2.6% of all new bleeding disorder registrations in the UK. The management of the bleeding phenotype associated with these disorders is poorly described. Systematic review and meta-analysis to determine the bleeding rates associated with tranexamic acid, desmopressin, platelet transfusion, plasma transfusion and recombinant activated factor VII, for patients with unclassified bleeding disorders undergoing surgery, childbirth or with menorrhagia. We searched for randomized controlled trials in MEDLINE, Embase, The Cochrane Central Register of Controlled Trials, PubMed, ISI Web of Science and the Transfusion Evidence Library from inception to 24 February 2020. Wherever appropriate, data were pooled using the metaprop function of STATA. Two studies with 157 participants with unclassified bleeding disorders were identified. The pooled risk of minor bleeding for patients undergoing surgery treated with peri-operative tranexamic acid was 11% (95% confidence interval 3--20%; n = 52; I2 = 0%); the risk for desmopressin and tranexamic acid in combination was 3% (95% confidence interval 0--7%; n = 71; I2 = 0%). There were no instances of major bleeding. In one procedure, 1 of 71 (1.4%), treated with a combination of desmopressin and tranexamic acid, the patient had a line-related deep vein thrombosis. There were too few patients treated to prevent postpartum haemorrhage or for menorrhagia to draw conclusions. The GRADE quality of evidence was very low suggesting considerable uncertainty over the results. However, both tranexamic acid, and the combination of tranexamic and desmopressin have high rates of haemostatic efficacy and have few adverse events. PROTOCOL REGISTRATION: PROSPERO CRD42020169727.

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%).

Desmopressin for reversal of Antiplatelet drugs in Stroke due to Haemorrhage (DASH): protocol for a phase II double-blind randomised controlled feasibility trial.

INTRODUCTION: Intracerebral haemorrhage (ICH) can be devastating and is a common cause of death and disability worldwide. Pre-ICH antiplatelet drug use is associated with a 27% relative increase in 1 month case fatality compared with patients not using antithrombotic drugs. We aim to assess the feasibility of conducting a randomised controlled testing the safety and efficacy of desmopressin for patients with antiplatelet-associated ICH. METHODS AND ANALYSIS: We aim to include 50 patients within 24 hours of spontaneous ICH onset, associated with oral antiplatelet drug(s) use in at least the preceding 7 days. Patients will be randomised (1:1) to receive intravenous desmopressin 20 µg in 50 mL sodium chloride 0.9% infused over 20 min or matching placebo. We will mask participants, relatives and outcome assessors to treatment allocation. Feasibility outcomes include proportion of patients approached being randomised, number of patients receiving allocated treatment, rate of recruitment and adherence to treatment and follow-up. Secondary outcomes include change in ICH volume at 24 hours; hyponatraemia at 24 hours, length of hospital stay, discharge destination, early death less than 28 days, death or dependency at day 90, death up to day 90, serious adverse events (including thromboembolic events) up to day 90; disability (Barthel index, day 90), quality of life (EuroQol 5D (EQ-5D), day 90), cognition (telephone mini-mental state examination day 90) and health economic assessment (EQ-5D). ETHICS AND DISSEMINATION: The Desmopressin for reversal of Antiplatelet drugs in Stroke due to Haemorrhage (DASH) trial received ethical approval from the East Midlands-Nottingham 2 research ethics committee (18/EM/0184). The DASH trial is funded by National Institute for Health and Care Research RfPB grant: PB-PG-0816-20011. Trial results will be published in a peer reviewed academic journal and disseminated through academic conferences and through patient stroke support groups. Reporting will be in compliance with Consolidated Standards of Reporting Trials recommendations. TRIAL REGISTRATION NUMBERS: NCT03696121; ISRCTN67038373; EudraCT 2018-001904-12.

Bleeding of unknown cause and unclassified bleeding disorders; diagnosis, pathophysiology and management.

Bleeding of unknown cause (BUC), also known as unclassified bleeding disorders (UBD), has been defined as a clear bleeding tendency in the presence of normal haemostatic tests. There are challenges in the diagnosis and management of these patients. BUC/UBD encompasses a heterogenous group of disorders which may include undiagnosed rare monogenic diseases, polygenic reasons for bleeding; and patients without a clear bleeding disorder but with a previous bleeding event. Nevertheless, these patients may have heavy menstrual bleeding or be at risk of bleeding when undergoing surgical procedures, or childbirth; optimizing haemostasis and establishing a mode of inheritance is important to minimize morbidity. The bleeding score has been used to clinically assess and describe these patients, but its value remains uncertain. In addition, accurate distinction between normal and pathological bleeding remains difficult. Several studies have investigated cohorts of these patients using research haemostasis tests, including thrombin generation and fibrinolytic assays, yet no clear characteristics have consistently emerged. Thus far, detailed genetic analysis of these patients has not been fruitful in unravelling the cause of bleeding. There is a need for standardization of diagnosis and management guidelines for these patients. This review gives an overview of this field with some suggestions for future research.

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 single centre retrospective study of low dose prophylaxis with extended half-life factor IX for severe haemophilia B.

INTRODUCTION: Extended half-life factor IX concentrates (EHL-FIX) can be administered weekly to prevent bleeding for persons with severe haemophilia B. We report the experience of a large UK haemophilia comprehensive care centre using low dose EHL-FIX for persons with severe haemophilia B. AIM: The low doses used in real world are approximately half of the doses used in clinical trials. We aim to assess the efficacy and safety of low dose EHL-FIX. METHODS: Data from a cohort of 13 patients who were switched from standard half-life factor IX (SHL-FIX) to Alprolix® (mean dose 31.5 IU/kg) and seven patients who switched from standard half-life factor IX to Idelvion® (mean dose 20.2 IU/kg) were included. RESULTS: The median annualized bleeding rate was similar for SHL-FIX (median 3, interquartile range [IQR] 1-5) and EHL-FIX (median 3, IQR 1-5.25). Quality of life scores, measured using the European Quality of Life 5 Dimensions assessment were similar for SHL-FIX (median 0.76, IQR: 0.63-0.84) and EHL-FIX (median 0.79, IQR: 0.58-0.88). CONCLUSION: This study shows that EHL-FIX given at low doses can be effective for prevention of bleeding for persons with severe haemophilia B.

Rebleeding and Mortality After Lower Gastrointestinal Bleeding in Patients Taking Antiplatelets or Anticoagulants.

BACKGROUND & AIMS: Patients who develop lower gastrointestinal bleeding (LGIB) while receiving anticoagulants or anti-platelets have increased severity of bleeding and risk of rebleeding. We compared outcomes of patients receiving antiplatelets, anticoagulants, or direct oral anticoagulants (DOACs) who develop LGIB, as well as the effects of withholding these drugs on their course of bleeding. METHODS: We performed a retrospective study of 2528 consecutive adult patients with LGIB at 143 hospitals in the United Kingdom, from September through December 2015; 917 were taking anticoagulant or antiplatelet drugs and 1218 were taking neither (unexposed). We collected data on demographic features of patients, interventions or medications, outcomes, laboratory test results, and patient readmission until patient death, discharge, or 28 days after admission (whichever came first). Rebleeding was defined as additional transfusion requirements and/or a decrease in hematocrit ≥20% after 24 hrs of clinical stability. Multivariate regression was used to examine the relationship between drug class on presentation with LGIB and rebleeding, mortality, and cardiovascular events. Rates of rebleeding and cardiovascular complications in patients who had these drugs withheld were also analyzed. RESULTS: Patients receiving antiplatelets, but not those receiving warfarin (n = 232) or DOACs (n = 102), had a higher risk of in-hospital rebleeding (monotherapy hazard ratio [HR], 3.57; 95% CI, 1.13-11.28; n = 504 and dual antiplatelet therapy hazard ratio, 5.3; 95% CI, 1.56-18.54; n = 79) compared with the unexposed group. This risk was not lower in patients who received antiplatelets and had the drug withheld for fewer than 5 days, compared to those who continued the drug throughout admission (HR, 0.98; 95% CI, 0.45-2.17) No differences were observed in risk-adjusted mortality or readmission with further bleeding for patients receiving antiplatelets, DOACs, or warfarin. Cardiovascular events were too few to allow meaningful comparison. CONCLUSIONS: In patients with LGIB, antiplatelet drugs, but not warfarin or DOACs, are associated with an increased risk of rebleeding. Withholding antiplatelets during admission does not lead to reduction in rebleeding.