Evaluating pharmacological THRomboprophylaxis in Individuals undergoing superficial endoVEnous treatment across NHS and private clinics in the UK: a multi-centre, assessor-blind, randomised controlled trial-THRIVE trial.

INTRODUCTION: Endovenous therapy is the first choice management for symptomatic varicose veins in NICE guidelines, with 56-70 000 procedures performed annually in the UK. Venous thromboembolism (VTE), including deep vein thrombosis (DVT) and pulmonary embolism (PE), is a known complication of endovenous therapy, occurring at a rate of up to 3.4%. Despite 73% of UK practitioners administering pharmacological thromboprophylaxis to reduce VTE, no high-quality evidence supporting this practice exists. Pharmacological thromboprophylaxis may have clinical and cost benefit in preventing VTE; however, further evidence is needed. This study aims to establish whether when endovenous therapy is undertaken: a single dose or course of pharmacological thromboprophylaxis alters the risk of VTE; pharmacological thromboprophylaxis is associated with an increased rate of bleeding events; pharmacological prophylaxis is cost effective. METHODS AND ANALYSIS: A multi-centre, assessor-blind, randomised controlled trial (RCT) will recruit 6660 participants from 40 NHS and private sites across the UK. Participants will be randomised to intervention (single dose or extended course of pharmacological thromboprophylaxis plus compression) or control (compression alone). Participants will undergo a lower limb venous duplex ultrasound scan at 21-28 days post-procedure to identify asymptomatic DVT. The duplex scan will be conducted locally by blinded assessors. Participants will be contacted remotely for follow-up at 7 days and 90 days post-procedure. The primary outcome is imaging-confirmed lower limb DVT with or without symptoms or PE with symptoms within 90 days of treatment. The main analysis will be according to the intention-to-treat principle and will compare the rates of VTE at 90 days, using a repeated measures analysis of variance, adjusting for any pre-specified strongly prognostic baseline covariates using a mixed effects logistic regression. ETHICS AND DISSEMINATION: Ethical approval was granted by Brent Research Ethics Committee (22/LO/0261). Results will be disseminated in a peer-reviewed journal and presented at national and international conferences. TRIAL REGISTRATION NUMBER: ISRCTN18501431.

A UK consensus statement on thromboprophylaxis for autologous breast reconstruction.

Microsurgical breast reconstruction accounts for 22% of breast reconstructions in the UK. Despite thromboprophylaxis, venous thromboembolism (VTE) occurs in up to 4% of cases. Using a Delphi process, this study established a UK consensus on VTE prophylaxis strategy, for patients undergoing autologous breast reconstruction using free-tissue transfer. It captured geographically divergent views, producing a guide that reflected the peer opinion and current evidence base. METHODS: Consensus was ascertained using a structured Delphi process. A specialist from each of the UK's 12 regions was invited to the expert panel. Commitment to three to four rounds of questions was sought at enrollment. Surveys were distributed electronically. An initial qualitative free-text survey was distributed to identify likely lines of consensus and dissensus. Each panelist was provided with full-text versions of key papers on the topic. Initial free-text responses were analyzed to develop a set of structured quantitative statements, which were refined via a second survey as a consensus was approached. RESULTS: The panel comprised 18 specialists: plastic surgeons and thrombosis experts from across the UK. Each specialist completed three rounds of surveys. Together, these plastic surgeons reported having performed more than 570 microsurgical breast reconstructions in the UK in 2019. A consensus was reached on 27 statements, detailing the assessment and delivery of VTE prophylaxis. CONCLUSION: To our knowledge, this is the first study to collate current practice, expert opinion from across the UK, and a literature review. The output was a practical guide for VTE prophylaxis for microsurgical breast reconstruction in any UK microsurgical breast reconstruction unit.

Decision-analysis modeling of effectiveness and cost-effectiveness of pharmacologic thromboprophylaxis for surgical inpatients using variable risk assessment models or other strategies.

BACKGROUND: Surgical inpatients are at a risk of venous thromboembolism (VTE), which can be life-threatening or result in chronic complications. Thromboprophylaxis reduces the VTE risk but incurs costs and may increase bleeding risk. Risk assessment models (RAMs) are currently used to target thromboprophylaxis at high-risk patients. OBJECTIVES: To determine the balance of cost, risk, and benefit for different thromboprophylaxis strategies in adult surgical inpatients, excluding patients who underwent major orthopedic surgery or were under critical care and pregnant women. METHODS: Decision analytic modeling was performed to estimate the following outcomes for alternative thromboprophylaxis strategies: thromboprophylaxis usage; VTE incidence and treatment; major bleeding; chronic thromboembolic complications; and overall survival. Strategies compared were as follows: no thromboprophylaxis; thromboprophylaxis for all; and thromboprophylaxis given according to RAMs (Caprini and Pannucci). Thromboprophylaxis is assumed to be given for the duration of hospitalization. The model evaluates lifetime costs and quality-adjusted life-years (QALYs) within England's health and social care services. RESULTS: Thromboprophylaxis for all surgical inpatients had a 70% probability of being the most cost-effective strategy (at a £20 000 per QALY threshold). RAM-based prophylaxis would be the most cost-effective strategy if a RAM with a higher sensitivity (99.9%) were available for surgical inpatients. QALY gains were mainly due to reduced postthrombotic complications. The optimal strategy was sensitive to several other factors such as the risk of VTE, bleeding and postthrombotic syndrome, duration of prophylaxis, and patient age. CONCLUSION: Thromboprophylaxis for all eligible surgical inpatients seemed to be the most cost-effective strategy. Default recommendations for pharmacologic thromboprophylaxis, with the potential to opt-out, may be superior to a complex risk-based opt-in approach.

Examining the benefit of graduated compression stockings in the prevention of hospital-associated venous thromboembolism in low-risk surgical patients: a multicentre cluster randomised controlled trial (PETS trial).

INTRODUCTION: Hospital-acquired thrombosis (HAT) is defined as any venous thromboembolism (VTE)-related event during a hospital admission or occurring up to 90 days post discharge, and is associated with significant morbidity, mortality and healthcare-associated costs. Although surgery is an established risk factor for VTE, operations with a short hospital stay (<48 hours) and that permit early ambulation are associated with a low risk of VTE. Many patients undergoing short-stay surgical procedures and who are at low risk of VTE are treated with graduated compression stockings (GCS). However, evidence for the use of GCS in VTE prevention for this cohort is poor. METHODS AND ANALYSIS: A multicentre, cluster randomised controlled trial which aims to determine whether GCS are superior in comparison to no GCS in the prevention of VTE for surgical patients undergoing short-stay procedures assessed to be at low risk of VTE. A total of 50 sites (21 472 participants) will be randomised to either intervention (GCS) or control (no GCS). Adult participants (18-59 years) who undergo short-stay surgical procedures and are assessed as low risk of VTE will be included in the study. Participants will provide consent to be contacted for follow-up at 7-days and 90-days postsurgical procedure. The primary outcome is the rate of symptomatic VTE, that is, deep vein thrombosis or pulmonary embolism during admission or within 90 days. Secondary outcomes include healthcare costs and changes in quality of life. The main analysis will be according to the intention-to-treat principle and will compare the rates of VTE at 90 days, measured at an individual level, using hierarchical (multilevel) logistic regression. ETHICS AND DISSEMINATION: Ethical approval was granted by the Camden and Kings Cross Research Ethics Committee (22/LO/0390). Findings will be published in a peer-reviewed journal and presented at national and international conferences. TRIAL REGISTRATION NUMBER: ISRCTN13908683.

Factor XIII levels, clot strength, and impact of fibrinogen concentrate in infants undergoing cardiopulmonary bypass: a mechanistic sub-study of the FIBCON trial.

BACKGROUND: Acquired factor XIII (FXIII) deficiency after major surgery can increase postoperative bleeding. We evaluated FXIII contribution to clot strength and the effect of fibrinogen concentrate administration on FXIII activity in infants undergoing cardiac surgery using cardiopulmonary bypass. METHODS: We conducted a prospectively planned, mechanistic sub-study, nested within the Fibrinogen Concentrate Supplementation in the Management of Bleeding During Paediatric Cardiopulmonary Bypass: A Phase 1B/2A, Open-Label Dose Escalation Study (FIBCON) trial, which investigated fibrinogen concentrate supplementation during cardiopulmonary bypass (ISRCTN: 50553029) in 111 infants (median age 6.4 months). The relationships between platelet number, fibrinogen concentration, and FXIII activity with rotational thromboelastometry clot strength (EXTEM-MCF) in blood taken immediately before cardiopulmonary bypass and after separation from bypass were estimated using multivariable linear regression. Changes in coagulation variables over time were quantified using a generalised linear model comparing three groups: fibrinogen concentrate-supplemented infants, placebo, and a third cohort with lower bleeding risk. RESULTS: Overall, 48% of the variability (multivariable R2) in EXTEM-MCF clot strength was explained by three factors: the largest contribution was from FXIII activity (partial R2=0.21), followed by platelet number (partial R2=0.14), and fibrinogen concentration (partial R2=0.095). During cardiopulmonary bypass, mean platelet count fell by a similar amount in the three groups (-36% to -41%; interaction P=0.98). Conversely, fibrinogen concentration increased in all three groups: 132% in the fibrinogen concentrate-supplemented group, 26% in the placebo group, and 51% in the low-risk group. A similar increase was observed for FXIII activity (61%, 23%, and 25%, respectively; interaction P<0.0001). CONCLUSIONS: FXIII contribution to clot strength is considerable in infants undergoing cardiac surgery. Fibrinogen concentrate supplementation also increased FXIII activity, and hence clot strength. CLINICAL TRIAL REGISTRATION: ISRCTN: 50553029.

Modelling acute antibody-mediated rejection of human kidney transplants using ex-vivo warm machine perfusion.

BACKGROUND: Transplant rejection is a major cause of graft loss and morbidity. Currently, no human models of antibody-mediated rejection (AMR) exist, limiting mechanistic investigation and organ-specific targeted therapy. Here, using 12 human kidneys and ex-vivo normothermic machine perfusion, we demonstrate phenotypes of AMR after addition of antibodies against either human HLA class I or blood group antigens (A, B), thus modelling clinical AMR that can follow HLA incompatible (HLAi) or blood group incompatible (ABOi) transplantation. METHODS: Discarded human kidneys with wide ranging demographics and cold ischaemia times (11-54 h) were perfused with red blood cells and fresh frozen plasma (FFP) as a source of complement/coagulation factors. For the HLAi model, 600 µg of W6/32 anti-class 1 HLA antibody was added to the circuit (time '0'). For the ABOi model, high titre FFP of the relevant blood group antibody was added. Renal blood flow index (RBFi, mL/min/100 g), C3 desArg, prothrombin fragments 1 + 2 and histology were determined. Our endpoints included haemodynamic changes, thrombosis, and biopsy proven complement deposition. FINDINGS: Compared to control kidneys perfused without anti-donor antibodies, both models demonstrated haemodynamic collapse after antibody perfusion with only the HLAi model showing glomerular C4d deposition. INTERPRETATION: We show that a clinically relevant human kidney model of AMR is feasible, and anticipate that these models, with refinements, could provide a basis to test different strategies to prevent AMR. FUNDING: The Rosetrees and Stonygate Trust, The Royal College of Surgeons of England Fellowship Grant, NIHR Biomedical Research Centre/KCL Early Career Grant, Kidney Research U.K.

Awareness of venous thromboembolism among patients with cancer: Preliminary findings from a global initiative for World Thrombosis Day.

BACKGROUND: Cancer-associated venous thromboembolism (CAT) has detrimental impact on patients' clinical outcomes and quality of life. Data on CAT education, communication, and awareness among the general cancer population are scanty. METHODS: We present the preliminary results of an ongoing patient-centered survey including 27 items covering major spheres of CAT. The survey, available in 14 languages, was promoted and disseminated online through social networks, email newsletters, websites, and media. RESULTS: As of September 20, 2022, 749 participants from 27 countries completed the survey. Overall, 61.8% (n = 460) of responders were not aware of their risk of CAT. Among those who received information on CAT, 26.2% (n = 56) were informed only at the time of CAT diagnosis. Over two thirds (69.1%, n = 501) of participants received no education on signs and symptoms of venous thromboembolism (VTE); among those who were educated about the possible clinical manifestations, 58.9% (n = 119) were given instructions to seek consultation in case of VTE suspicion. Two hundred twenty-four respondents (30.9%) had a chance to discuss the potential use of primary thromboprophylaxis with health-care providers. Just over half (58.7%, n = 309) were unaware of the risks of bleeding associated with anticoagulation, despite being involved in anticoagulant-related discussions or exposed to anticoagulants. Most responders (85%, n = 612) valued receiving CAT education as highly relevant; however, 51.7% (n = 375) expressed concerns about insufficient time spent and clarity of education received. CONCLUSIONS: This ongoing survey involving cancer patients with diverse ethnic, cultural, and geographical backgrounds highlights important patient knowledge gaps. These findings warrant urgent interventions to improve education and awareness, and reduce CAT burden.

Natural history of PF4 antibodies in vaccine-induced immune thrombocytopenia and thrombosis.

The COVID-19 pandemic has resulted in the rapid development of a range of vaccines against SARS-CoV-2. Vaccine-induced immune thrombocytopenia and thrombosis (VITT) is a rare but life-threatening complication of primarily adenoviral-based vaccines associated with the presence of antibodies to a PF4/polyanion neoepitope and measured by using enzyme-linked immunosorbent assays. Presented are serial anti-PF4/polyanion antibody, platelet, and D-dimer measurements in a large cohort of patients and their relation to relapse. Overall, 51% of patients using the Stago assay had persistently positive anti-PF4/polyanion levels 100 days' postdiagnosis, whereas 94% of patients monitored by using the Immucor assay remain positive. The median duration of positivity of the PF4 assay is 87 days, with 72% of patients remaining positive after a median follow-up of 105 days. The use of plasma exchange seemed to reduce anti-PF4/polyanion levels and increase platelet counts in the acute setting more rapidly than other therapies. The rate of relapse in this study was 12.6%, with all relapsed cases exhibiting persistently positive PF4 antibodies and falling platelet counts. Only one patient had extension of their thrombosis. Overall, despite the persistence of PF4 antibodies in 72% of patients, the rate of relapse was low and did not seem to result in recrudescence of the aggressive clinical picture seen at index presentation. Monitoring of these patients in the UK cohort is ongoing and will aid in definition of the natural history of this novel condition.

Effect of Antiplatelet Therapy on Survival and Organ Support-Free Days in Critically Ill Patients With COVID-19: A Randomized Clinical Trial.

Importance: The efficacy of antiplatelet therapy in critically ill patients with COVID-19 is uncertain. Objective: To determine whether antiplatelet therapy improves outcomes for critically ill adults with COVID-19. Design, Setting, and Participants: In an ongoing adaptive platform trial (REMAP-CAP) testing multiple interventions within multiple therapeutic domains, 1557 critically ill adult patients with COVID-19 were enrolled between October 30, 2020, and June 23, 2021, from 105 sites in 8 countries and followed up for 90 days (final follow-up date: July 26, 2021). Interventions: Patients were randomized to receive either open-label aspirin (n = 565), a P2Y12 inhibitor (n = 455), or no antiplatelet therapy (control; n = 529). Interventions were continued in the hospital for a maximum of 14 days and were in addition to anticoagulation thromboprophylaxis. Main Outcomes and Measures: The primary end point was organ support-free days (days alive and free of intensive care unit-based respiratory or cardiovascular organ support) within 21 days, ranging from -1 for any death in hospital (censored at 90 days) to 22 for survivors with no organ support. There were 13 secondary outcomes, including survival to discharge and major bleeding to 14 days. The primary analysis was a bayesian cumulative logistic model. An odds ratio (OR) greater than 1 represented improved survival, more organ support-free days, or both. Efficacy was defined as greater than 99% posterior probability of an OR greater than 1. Futility was defined as greater than 95% posterior probability of an OR less than 1.2 vs control. Intervention equivalence was defined as greater than 90% probability that the OR (compared with each other) was between 1/1.2 and 1.2 for 2 noncontrol interventions. Results: The aspirin and P2Y12 inhibitor groups met the predefined criteria for equivalence at an adaptive analysis and were statistically pooled for further analysis. Enrollment was discontinued after the prespecified criterion for futility was met for the pooled antiplatelet group compared with control. Among the 1557 critically ill patients randomized, 8 patients withdrew consent and 1549 completed the trial (median age, 57 years; 521 [33.6%] female). The median for organ support-free days was 7 (IQR, -1 to 16) in both the antiplatelet and control groups (median-adjusted OR, 1.02 [95% credible interval {CrI}, 0.86-1.23]; 95.7% posterior probability of futility). The proportions of patients surviving to hospital discharge were 71.5% (723/1011) and 67.9% (354/521) in the antiplatelet and control groups, respectively (median-adjusted OR, 1.27 [95% CrI, 0.99-1.62]; adjusted absolute difference, 5% [95% CrI, -0.2% to 9.5%]; 97% posterior probability of efficacy). Among survivors, the median for organ support-free days was 14 in both groups. Major bleeding occurred in 2.1% and 0.4% of patients in the antiplatelet and control groups (adjusted OR, 2.97 [95% CrI, 1.23-8.28]; adjusted absolute risk increase, 0.8% [95% CrI, 0.1%-2.7%]; 99.4% probability of harm). Conclusions and Relevance: Among critically ill patients with COVID-19, treatment with an antiplatelet agent, compared with no antiplatelet agent, had a low likelihood of providing improvement in the number of organ support-free days within 21 days. Trial Registration: ClinicalTrials.gov Identifier: NCT02735707.

Evaluation of novel coagulation and platelet function assays in patients with chronic kidney disease.

BACKGROUND: Hemostasis evaluation in chronic kidney disease (CKD) is critical for optimal management of thrombotic and bleeding events. Standard coagulation screens are inadequate for predicting coagulopathy in CKD. OBJECTIVE: To evaluate hemostasis parameters in patients with different stages of CKD using novel coagulation assays. PATIENTS/METHODS: Cross-sectional study of 30 healthy controls (HC) and 120 CKD patients (10 Stage 2, 20 Stage 3, 20 Stage 4, 20 Stage 5 not requiring renal replacement therapy, 20 transplant, 10 newly started on hemodialysis [HD], 20 established on HD). Standard laboratory tests were performed in addition to rotational thromboelastometry (ROTEM), multiple electrode aggregometry (MEA), thrombin generation assays, D-dimer, and markers of thrombogenesis (thrombin-antithrombin [TAT]), fibrinolysis, and endothelial activation (intercellular adhesion molecule-1 [ICAM-1]). RESULTS: D-dimer, TAT, and ICAM-1 concentrations were significantly higher in patients with CKD than HC (P < .01). ROTEM maximum clot firmness was significantly higher in patients than in HC (P < .01). In CKD Stage 5 patients (pre-HD and started HD) adenosine diphosphate and thrombin receptor activating peptide MEA tests were significantly lower than HC indicating platelet aggregation defect (P < .05). Multivariate analysis confirmed the direct effect of estimated glomerular filtration rate (eGFR) in the variance of ROTEM and MEA tests. Endogenous thrombin potential and peak thrombin were not statistically different between groups, but Stage 5 CKD patients had prolonged lag time (7.91 vs. 6.33, P < .001) and time to thrombin peak (10.8 vs. 9.5, P < .05) compared to HC. CONCLUSIONS: Patients with CKD exhibit features of concomitant hypercoagulability measured by ROTEM and platelet dysfunction measured with MEA. eGFR was an independent determinant of platelet dysfunction and hypercoagulability.

Antifibrinolytic Drugs for the Prevention of Bleeding in Pediatric Cardiac Surgery on Cardiopulmonary Bypass: A Systematic Review and Meta-analysis.

BACKGROUND: Bleeding is one of the commonest complications affecting children undergoing cardiac surgery on cardiopulmonary bypass. Antifibrinolytic drugs are part of a multifaceted approach aimed at reducing bleeding, though sufficiently sized pediatric studies are sparse, and dosing algorithms are heterogeneous. Our objective was to evaluate the efficacy and safety of antifibrinolytic agents as well as the effectiveness of different dosing regimens in pediatric cardiac surgery using cardiopulmonary bypass. METHODS: We performed a systematic review and meta-analysis evaluating randomized controlled trials published between 1980 and 2019, identified by searching the databases MEDLINE, EMBASE, PubMed, and CENTRAL. All studies investigating patients <18 years of age without underlying hematological disorders were included. The primary outcome was postoperative bleeding; secondary end points included blood product transfusion, mortality, and safety (thromboses, anaphylaxis, renal or neurological dysfunction, and seizures). Different dosing regimens were compared. Studies were dual appraised, outcomes were reported descriptively and, if appropriate, quantitatively using the Review Manager 5 (REVMAN 5) software (The Cochrane Collaboration). RESULTS: Thirty of 209 articles were included, evaluating the following drugs versus control: aprotinin n = 14, tranexamic acid (TXA) n = 12, and epsilon-aminocaproic acid (EACA) n = 4. The number of participants per intervention group ranged from 11 to 100 (median, 25; interquartile range [IQR], 20.5) with a wide age span (mean, 13 days to 5.8 years) and weight range (mean, 3.1-26.3 kg). Methodological quality was low to moderate.All agents reduced mean 24-hour blood loss compared to control: aprotinin by 6.0 mL/kg (95% confidence interval [CI], -9.1 to -3.0; P = .0001), TXA by 9.0 mL/kg (95% CI, -11.3 to -6.8; P < .00001), and EACA by 10.5 mL/kg (95% CI, -21.1 to 0.0; P = .05). Heterogeneity was low for TXA (I2 = 29%; P = .19), moderate for aprotinin (I2 = 41%; P = .11), and high for EACA (I2 = 95%; P < .00001). All agents also reduced 24-hour blood product transfusion. There was no clear dose-response effect for TXA nor aprotinin. Studies were underpowered to detect significant differences in mortality, thromboses, anaphylaxis, and renal or neurological dysfunction. CONCLUSIONS: The available data demonstrate efficacy for all 3 antifibrinolytic drugs. Therefore, the agent with the most favorable safety profile should be used. As sufficient data are lacking, large comparative trials are warranted to assess the relative safety and appropriate dosing regimens in pediatrics.

Splanchnic vein thrombosis-related mortality in the Veneto region (Italy), 2008-2019: Retrospective analysis of epidemiological data.

BACKGROUND: Splanchnic vein thrombosis (SVT) is an uncommon manifestation of venous thromboembolism. Epidemiological data on SVT-related mortality rate is not available to date. METHODS: We investigated time trends in SVT-related mortality rate, 2008-2019, in Veneto, an Italian high-income region of approximatively 5,000,000 inhabitants. SVT-related deaths were identified by the following ICD-10 codes: I81 (portal vein thrombosis), K75.1 (phlebitis of portal vein), K76.3 (liver infarction), K76.5 (hepatic veno-occlusive disease) or I82.0 (Budd-Chiari syndrome). RESULTS: During the study period, a total of 557,932 deaths were recorded. SVT was reported in 823 cases; 776 (94%) consisted of portal vein thrombosis. The age-standardized SVT-related mortality rate varied from 1.47 (year 2008) to 1.52 (year 2019) per 100,000 person-years. An increase in the cause-specific annual mortality rate was observed in women (0.56 in 2008 to 1.04 per 100,000 person-years in 2019; average annual percent change +5.7%, 95%CI +3.1; +8.3%). In men, the cause-specific mortality rate moved from 2.53 in 2008 to 2.03 per 100,000 person-years in 2019 (average annual percent change -1.2%, 95%CI -4.0; +1.6%). After conditioning for age and sex, the odds of having a concomitant liver disease were higher for SVT-related deaths (OR 31.6; 95%CI 17.1-37.0) compared with non-SVT-related deaths. This also applies to gastrointestinal cancers (OR 1.28; 95%CI 1.07-1.55), although to a lesser extent. CONCLUSIONS: We report first epidemiological estimates of SVT-related mortality in a Western country. These values will serve as a reference to weight novel potential factors associated with SVT-related death and interpret them from an epidemiological perspective.

Tranexamic Acid in Gastrointestinal Bleeding: A Systematic Review and Meta-Analysis.

OBJECTIVES: Tranexamic acid is proposed as a treatment for gastrointestinal bleeding. The Haemorrhage Alleviation with Tranexamic Acid-Intestinal System trial evaluated extended-use (24 hr) high-dose tranexamic acid, prompting a reappraisal for tranexamic acid in gastrointestinal bleeding. DATA SOURCES: We conducted a systematic review and meta-analysis of randomized controlled trials comparing tranexamic acid with usual care or placebo in adults with gastrointestinal bleeding. We searched MEDLINE, EMBASE, and CENTRAL (inception to September 2019). DATA SELECTION: Two reviewers independently screened citations, extracted data, and assessed the risk of bias using the Cochrane risk of bias tool in duplicate. The main outcomes were mortality, bleeding, and adverse events. DATA EXTRACTION: Studies were analyzed as high-dose IV tranexamic acid versus all other dosing strategies for tranexamic acid using fixed-effects models. We assessed certainty of evidence using the Grading of Recommendations Assessment, Development, and Evaluation approach. DATA SYNTHESIS: Five randomized controlled trials evaluated extended-use high-dose IV tranexamic acid, seven evaluating low-dose IV or enteral tranexamic acid. Extended-use high-dose IV tranexamic acid did not reduce mortality (relative risk, 0.98%; 95% CI, 0.88-1.09; I2 = 63%; high certainty) or bleeding (relative risk, 0.92; 95% CI, 0.82-1.04; p = 0.17 and absolute risk differences, -0.7%; 95% CI, -1.5 to 0.3; high certainty) but resulted in a small increase in deep venous thrombosis (relative risk, 2.01; 95% CI, 1.08-3.72; I2 = 0%), pulmonary embolism (relative risk, 1.78; 95% CI, 1.06-3.0; I2 = 0%), and seizure (relative risk, 1.73; 95% CI, 1.03-2.93) with high certainty. Low-dose IV/enteral tranexamic acid did not reduce mortality (relative risk, 0.62; 95% CI, 0.36-1.09; I2 = 0%) but did reduce risk of rebleeding (relative risk, 0.5; 95% CI, 0.33-0.75; I2 = 9%) and need for surgery (relative risk, 0.58; 95% CI, 0.38-0.88; I2 = 11%), with moderate certainty. CONCLUSIONS: Extended-use high-dose IV tranexamic acid does not improve mortality or bleeding outcomes and increases adverse events. Low-dose/enteral tranexamic acid may be effective in reducing hemorrhage; more evidence is required to demonstrate its safety.

Clinical Features of Vaccine-Induced Immune Thrombocytopenia and Thrombosis.

BACKGROUND: Vaccine-induced immune thrombocytopenia and thrombosis (VITT) is a new syndrome associated with the ChAdOx1 nCoV-19 adenoviral vector vaccine against severe acute respiratory syndrome coronavirus 2. Data are lacking on the clinical features of and the prognostic criteria for this disorder. METHODS: We conducted a prospective cohort study involving patients with suspected VITT who presented to hospitals in the United Kingdom between March 22 and June 6, 2021. Data were collected with the use of an anonymized electronic form, and cases were identified as definite or probable VITT according to prespecified criteria. Baseline characteristics and clinicopathological features of the patients, risk factors, treatment, and markers of poor prognosis were determined. RESULTS: Among 294 patients who were evaluated, we identified 170 definite and 50 probable cases of VITT. All the patients had received the first dose of ChAdOx1 nCoV-19 vaccine and presented 5 to 48 days (median, 14) after vaccination. The age range was 18 to 79 years (median, 48), with no sex preponderance and no identifiable medical risk factors. Overall mortality was 22%. The odds of death increased by a factor of 2.7 (95% confidence interval [CI], 1.4 to 5.2) among patients with cerebral venous sinus thrombosis, by a factor of 1.7 (95% CI, 1.3 to 2.3) for every 50% decrease in the baseline platelet count, by a factor of 1.2 (95% CI, 1.0 to 1.3) for every increase of 10,000 fibrinogen-equivalent units in the baseline d-dimer level, and by a factor of 1.7 (95% CI, 1.1 to 2.5) for every 50% decrease in the baseline fibrinogen level. Multivariate analysis identified the baseline platelet count and the presence of intracranial hemorrhage as being independently associated with death; the observed mortality was 73% among patients with platelet counts below 30,000 per cubic millimeter and intracranial hemorrhage. CONCLUSIONS: The high mortality associated with VITT was highest among patients with a low platelet count and intracranial hemorrhage. Treatment remains uncertain, but identification of prognostic markers may help guide effective management. (Funded by the Oxford University Hospitals NHS Foundation Trust.).

Risk assessment models for venous thromboembolism in hospitalised adult patients: a systematic review.

INTRODUCTION: Hospital-acquired thrombosis accounts for a large proportion of all venous thromboembolism (VTE), with significant morbidity and mortality. This subset of VTE can be reduced through accurate risk assessment and tailored pharmacological thromboprophylaxis. This systematic review aimed to determine the comparative accuracy of risk assessment models (RAMs) for predicting VTE in patients admitted to hospital. METHODS: A systematic search was performed across five electronic databases (including MEDLINE, EMBASE and the Cochrane Library) from inception to February 2021. All primary validation studies were eligible if they examined the accuracy of a multivariable RAM (or scoring system) for predicting the risk of developing VTE in hospitalised inpatients. Two or more reviewers independently undertook study selection, data extraction and risk of bias assessments using the PROBAST (Prediction model Risk Of Bias ASsessment Tool) tool. We used narrative synthesis to summarise the findings. RESULTS: Among 6355 records, we included 51 studies, comprising 24 unique validated RAMs. The majority of studies included hospital inpatients who required medical care (21 studies), were undergoing surgery (15 studies) or receiving care for trauma (4 studies). The most widely evaluated RAMs were the Caprini RAM (22 studies), Padua prediction score (16 studies), IMPROVE models (8 studies), the Geneva risk score (4 studies) and the Kucher score (4 studies). C-statistics varied markedly between studies and between models, with no one RAM performing obviously better than other models. Across all models, C-statistics were often weak (<0.7), sometimes good (0.7-0.8) and a few were excellent (>0.8). Similarly, estimates for sensitivity and specificity were highly variable. Sensitivity estimates ranged from 12.0% to 100% and specificity estimates ranged from 7.2% to 100%. CONCLUSION: Available data suggest that RAMs have generally weak predictive accuracy for VTE. There is insufficient evidence and too much heterogeneity to recommend the use of any particular RAM. PROSPERO REGISTRATION NUMBER: Steve Goodacre, Abdullah Pandor, Katie Sworn, Daniel Horner, Mark Clowes. A systematic review of venous thromboembolism RAMs for hospital inpatients. PROSPERO 2020 CRD42020165778. Available from https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=165778https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=165778.

Degradation of the Endothelial Glycocalyx Contributes to Metabolic Acidosis in Children Following Cardiopulmonary Bypass Surgery.

OBJECTIVES: Cardiopulmonary bypass surgery is complicated by metabolic acidosis, microvascular dysfunction, and capillary leak. The glycocalyx-a layer of proteins and sugars lining the vascular endothelium-is degraded during cardiopulmonary bypass. We aimed to describe the kinetics of glycocalyx degradation during and following cardiopulmonary bypass. We hypothesized that cleavage of negatively charged fragments of the glycocalyx would directly induce metabolic acidosis through changes in the strong ion gap (defined using Stewart's physicochemical approach to acid-base chemistry). We also investigated whether glycocalyx degradation was associated with failure of endothelial function and cardiovascular dysfunction. DESIGN: Single-center prospective cohort study. SETTING: Twenty-two bed surgical/medical PICU. PATIENTS: Twenty-seven term infants and children requiring cardiopulmonary bypass surgery for the correction/palliation of congenital heart disease. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We recruited 27 patients, 5 days to 57 months old. We prospectively sampled plasma prior to, during, and following cardiopulmonary bypass at predefined time points. We measured plasma concentrations of interleukin-6 (inflammatory marker), heparan sulfate (negatively charged glycocalyx glycosaminoglycan), and syndecan-1 (neutrally charged glycocalyx protein). We defined the following outcome measures: metabolic acidosis (strong ion gap), renal dysfunction (fold change in creatinine), capillary leak (fluid bolus volume), cardiovascular dysfunction (Vasoactive Inotropic Score), and length of ventilation. In linear regression models, maximum measured heparan sulfate concentration (negatively charged) was associated with metabolic acidosis (p = 0.016), renal dysfunction (p = 0.009), and length of ventilation (p = 0.047). In contrast, maximum measured syndecan-1 concentration (neutrally charged) was not associated with these clinical endpoints (p > 0.30 for all). CONCLUSIONS: Our data show that metabolic acidosis (increased strong ion gap) is associated with plasma concentration of heparan sulfate, a negatively charged glycosaminoglycan cleaved from the endothelial glycocalyx during cardiopulmonary bypass. In addition, cleavage of heparan sulfate was associated with renal dysfunction, capillary leak, and global markers of cardiovascular dysfunction. These data highlight the importance of designing translational therapies to protect the glycocalyx in cardiopulmonary bypass.

A living WHO guideline on drugs to prevent covid-19.

CLINICAL QUESTION: What is the role of drugs in preventing covid-19? WHY DOES THIS MATTER?: There is widespread interest in whether drug interventions can be used for the prevention of covid-19, but there is uncertainty about which drugs, if any, are effective. The first version of this living guideline focuses on the evidence for hydroxychloroquine. Subsequent updates will cover other drugs being investigated for their role in the prevention of covid-19. RECOMMENDATION: The guideline development panel made a strong recommendation against the use of hydroxychloroquine for individuals who do not have covid-19 (high certainty). HOW THIS GUIDELINE WAS CREATED: This living guideline is from the World Health Organization (WHO) and provides up to date covid-19 guidance to inform policy and practice worldwide. Magic Evidence Ecosystem Foundation (MAGIC) provided methodological support. A living systematic review with network analysis informed the recommendations. An international guideline development panel of content experts, clinicians, patients, an ethicist and methodologists produced recommendations following standards for trustworthy guideline development using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. UNDERSTANDING THE NEW RECOMMENDATION: The linked systematic review and network meta-analysis (6 trials and 6059 participants) found that hydroxychloroquine had a small or no effect on mortality and admission to hospital (high certainty evidence). There was a small or no effect on laboratory confirmed SARS-CoV-2 infection (moderate certainty evidence) but probably increased adverse events leading to discontinuation (moderate certainty evidence). The panel judged that almost all people would not consider this drug worthwhile. In addition, the panel decided that contextual factors such as resources, feasibility, acceptability, and equity for countries and healthcare systems were unlikely to alter the recommendation. The panel considers that this drug is no longer a research priority and that resources should rather be oriented to evaluate other more promising drugs to prevent covid-19. UPDATES: This is a living guideline. New recommendations will be published in this article and signposted by update notices to this guideline. READERS NOTE: This is the first version of the living guideline for drugs to prevent covid-19. It complements the WHO living guideline on drugs to treat covid-19. When citing this article, please consider adding the update number and date of access for clarity.

CIRSE Standards of Practice on Peri-operative Anticoagulation Management During Interventional Radiology Procedures.

This CIRSE Standards of Practice document is aimed at interventional radiologists and provides best practices for peri-operative anticoagulation management during interventional radiology procedures.