Extracellular histones: a unifying mechanism driving platelet-dependent extracellular vesicle release and thrombus formation in COVID-19.

BACKGROUND: COVID-19 can cause profound inflammation and coagulopathy, and while many mechanisms have been proposed, there is no known common pathway leading to a prothrombotic state. OBJECTIVES: From the beginning of the COVID-19 pandemic, elevated levels of extracellular histones have been found in plasma of patients infected with SARS-CoV-2. We hypothesized that platelet activation triggered by extracellular histones might represent a unifying mechanism leading to increased thrombin generation and thrombosis. METHODS: We utilized blood samples collected from an early clinical trial of hospitalized COVID-19 patients (NCT04360824) and recruited healthy subjects as controls. Using plasma samples, we measured the procoagulant and prothrombotic potential of circulating extracellular histones and extracellular vesicles (EVs). Platelet prothrombotic activity was assessed via thrombin generation potential and platelet thrombus growth. Circulating EVs were assessed for thrombin generation potential in vitro in plasma and enhancement of thrombotic susceptibility in vivo in mice. RESULTS AND CONCLUSIONS: Compared to controls, COVID-19 patients had elevated plasma levels of citrullinated histone H3, cell free DNA, nucleosomes, and EVs. Plasma from COVID-19 patients promoted platelet activation, platelet-dependent thrombin generation, thrombus growth under venous shear stress, and release of platelet-derived EVs. These prothrombotic effects of COVID-19 plasma were inhibited by an RNA aptamer that neutralizes both free and DNA-bound histones. EVs isolated from COVID-19 plasma enhanced thrombin generation in vitro and potentiated venous thrombosis in mice in vivo. We conclude that extracellular histones and procoagulant EVs drive the prothrombotic state in COVID-19 and that histone-targeted therapy may prove beneficial.

Extending venous thromboembolism secondary prevention with apixaban in cancer patients. The EVE trial.

BACKGROUND: Cancer-associated venous thromboembolism (VTE) management guideline recommendations include continued therapeutic anticoagulation while active cancer persists. The Federal Drug Administration label for apixaban for secondary VTE prevention includes a dose reduction to 2.5 mg twice daily after 6 months of treatment. OBJECTIVES: The study's purpose was to determine whether this dose reduction is advisable for cancer-associated VTE. METHODS: A randomized, double-blind trial compared apixaban 2.5 mg with 5 mg twice daily for 12 months among cancer patients with VTE who had completed 6 to 12 months of anticoagulation therapy. The primary outcome was combined major bleeding plus clinically relevant nonmajor bleeding. RESULTS: Of 370 patients recruited, 360 were included in the intention-to-treat analyses. Major plus clinically relevant nonmajor bleeding occurred in 16 of 179 patients (8.9%) in the apixaban 2.5 mg group compared with 22 of 181 patients (12.2%) in the 5 mg group (hazard ratio [HR], 0.72; 95% CI, 0.38-1.37; P = .39). Major bleeding occurred in 2.8% of the apixaban 2.5 mg group and in 2.2% of the 5 mg group (HR, 1.26; 95% CI, 0.34-4.66; P = .73). Recurrent VTE or arterial thrombosis occurred in 9 of 179 patients (5.0%) in the apixaban 2.5 mg group and 9 of 181 patients (5.0%) in the 5 mg group (HR, 1.0; 95% CI, 0.40-2.53; P = 1.00). All-cause mortality rates were similar between groups, 13% vs 12% (HR, 1.14; 95% CI, 0.63-2.04; P = .67). CONCLUSION: For secondary prevention of cancer-associated VTE, apixaban 2.5 mg compared with 5 mg twice daily did not lower combined bleeding events (EVE trial NCT03080883).

Standard prophylactic versus intermediate dose enoxaparin in adults with severe COVID-19: A multi-center, open-label, randomized controlled trial.

BACKGROUND: Coronavirus disease 2019 (COVID-19) is associated with coagulopathy but the optimal prophylactic anticoagulation therapy remains uncertain and may depend on COVID-19 severity. OBJECTIVE: To compare outcomes in hospitalized adults with severe COVID-19 treated with standard prophylactic versus intermediate dose enoxaparin. METHODS: We conducted a multi-center, open-label, randomized controlled trial comparing standard prophylactic dose versus intermediate dose enoxaparin in adults who were hospitalized with COVID-19 and admitted to an intensive care unit (ICU) and/or had laboratory evidence of coagulopathy. Patients were randomly assigned in a 1:1 ratio to receive standard prophylactic dose enoxaparin or intermediate weight-adjusted dose enoxaparin. The primary outcome was all-cause mortality at 30 days. Secondary outcomes included arterial or venous thromboembolism and major bleeding. RESULTS: A total of 176 patients (99 males and 77 females) underwent randomization. In the intention-to-treat population, all-cause mortality at 30 days was 15% for intermediate dose enoxaparin and 21% for standard prophylactic dose enoxaparin (odds ratio, 0.66; 95% confidence interval, 0.30-1.45; P = .31 by Chi-square test). Unadjusted Cox proportional hazards modeling demonstrated no significant difference in mortality between intermediate and standard dose enoxaparin (hazard ratio, 0.67; 95% confidence interval, 0.33-1.37; P = .28). Arterial or venous thrombosis occurred in 13% of patients assigned to intermediate dose enoxaparin and 9% of patients assigned to standard dose enoxaparin. Major bleeding occurred in 2% of patients in each arm. CONCLUSION: In hospitalized adults with severe COVID-19, standard prophylactic dose and intermediate dose enoxaparin did not differ significantly in preventing death or thrombosis at 30 days.

Anticoagulant interventions in hospitalized patients with COVID-19: A scoping review of randomized controlled trials and call for international collaboration.

INTRODUCTION: Coronavirus disease (COVID-19) is associated with a high incidence of thrombosis and mortality despite standard anticoagulant thromboprophylaxis. There is equipoise regarding the optimal dose of anticoagulant intervention in hospitalized patients with COVID-19 and consequently, immediate answers from high-quality randomized trials are needed. METHODS: The World Health Organization's International Clinical Trials Registry Platform was searched on June 17, 2020 for randomized controlled trials comparing increased dose to standard dose anticoagulant interventions in hospitalized COVID-19 patients. Two authors independently screened the full records for eligibility and extracted data in duplicate. RESULTS: A total of 20 trials were included in the review. All trials are open label, 5 trials use an adaptive design, 1 trial uses a factorial design, 2 trials combine multi-arm parallel group and factorial designs in flexible platform trials, and at least 15 trials have multiple study sites. With individual target sample sizes ranging from 30 to 3000 participants, the pooled sample size of all included trials is 12 568 participants. Two trials include only intensive care unit patients, and 10 trials base patient eligibility on elevated D-dimer levels. Therapeutic intensity anticoagulation is evaluated in 14 trials. All-cause mortality is part of the primary outcome in 14 trials. DISCUSSION: Several trials evaluate different dose regimens of anticoagulant interventions in hospitalized patients with COVID-19. Because these trials compete for sites and study participants, a collaborative effort is needed to complete trials faster, conduct pooled analyses and bring effective interventions to patients more quickly.

Pilot trial of semi-automated medical note writing using lexeme hypotheses.

Clinicians write a billion free text notes per year. These notes are typically replete with errors of all types. No established automated method can extract data from this treasure trove. The practice of medicine therefore remains haphazard and chaotic, resulting in vast economic waste. The lexeme hypotheses are based on our analysis of how records are created. They enable a computer system to predict what issue a clinician will need to address next, based on the environment in which the clinician is working, and what responses the clinician has selected to date. The system uses a lexicon storing the issues (queries) and a range of responses to the issues. When the clinician selects a response, a text fragment is added to the output file. In the first phase of this work, the notes of 69 returning hemophilia patients were scrutinized, and the lexicon was expanded to 847 lexeme queries and 7995 responses to enable the construction of completed notes. The quality of lexeme-generated notes from 20 consecutive subjects was then compared to the clinicians' conventional clinic notes. The system generated grammatically correct notes. In comparison to the traditional clinic note, the lexeme-generated notes were more complete (88 % compared with 62 %), and had less typographical and grammatical errors (0.8 versus 3.5 errors per note). The system notes and traditional notes averaged about 800 words, but the traditional notes had a much wider distribution of lengths. The note-creation rate from marshalling the data to completion using the system averaged 80 wpm, twice as fast as the typical clinician can type. The lexeme method generates more complete, grammatical and organized notes faster than traditional methods. The notes are completely computerized at inception, and they incorporate prompts for clinicians to address otherwise overlooked items. This pilot justifies further exploration of this methodology.

Apixaban and dalteparin in active malignancy-associated venous thromboembolism: The ADAM VTE trial.

BACKGROUND: Low-molecular-weight heparin is the guideline-endorsed treatment for cancer-associated venous thromboembolism (VTE). While apixaban is approved for the treatment of acute VTE, limited data support its use in cancer patients. OBJECTIVES: The primary outcome was major bleeding. Secondary outcomes included VTE recurrence and a composite of major plus clinically relevant non-major bleeding (CRNMB). PATIENTS/METHODS: Patients with cancer-associated VTE were randomly assigned to receive either apixaban 10 mg twice daily for seven days followed by 5 mg twice daily for six months or subcutaneous dalteparin (200 IU/kg for one month followed by 150 IU/kg once daily). RESULTS: Of 300 patients randomized, 287 were included in the primary analysis. Metastatic disease was present in 66% of subjects; 74% were receiving concurrent chemotherapy. Major bleeding occurred in 0% of 145 patients receiving apixaban, compared with 1.4% of 142 patients receiving dalteparin [P = .138; hazard ratio (HR) not estimable because of 0 bleeding event in apixaban group]. Recurrent VTE occurred in 0.7% of apixaban, compared to 6.3% of dalteparin patients [HR 0.099, 95% confidence interval [CI], 0.013-0.780, P = .0281). Major bleeding or CRNMB rates were 6% for both groups. CONCLUSIONS: Oral apixaban was associated with low major bleeding and VTE recurrence rates for the treatment of VTE in cancer patients.

Chart validation of inpatient International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) administrative diagnosis codes for venous thromboembolism (VTE) among intravenous immune globulin (IGIV) users in the Sentinel Distributed Database.

The Sentinel Distributed Database (SDD) is a database of patient administrative healthcare records, derived from insurance claims and electronic health records, sponsored by the US Food and Drug Administration for evaluation of medical product outcomes. There is limited information on the validity of diagnosis codes for acute venous thromboembolism (VTE) in the SDD and administrative healthcare data more generally.In this chart validation study, we report on the positive predictive value (PPV) of inpatient administrative diagnosis codes for acute VTE-pulmonary embolism (PE) or lower-extremity or site-unspecified deep vein thrombosis (DVT)-within the SDD. As part of an assessment of thromboembolic adverse event risk following treatment with intravenous immune globulin (IGIV), charts were obtained for 75 potential VTE cases, abstracted, and physician-adjudicated.VTE status was determined for 62 potential cases. PPVs for lower-extremity DVT and/or PE were 90% (95% CI: 73-98%) for principal-position diagnoses, 80% (95% CI: 28-99%) for secondary diagnoses, and 26% (95% CI: 11-46%) for position-unspecified diagnoses (originating from physician claims associated with an inpatient stay). Average symptom onset was 1.5 days prior to hospital admission (range: 19 days prior to 4 days after admission).PPVs for principal and secondary VTE discharge diagnoses were similar to prior study estimates. Position-unspecified diagnoses were less likely to represent true acute VTE cases.

Outcomes among North American patients with diffuse large B-cell lymphoma are independent of tumor Epstein-Barr virus positivity or immunosuppression.

The prevalence, presenting clinical and pathological characteristics, and outcomes for patients with diffuse large B-cell lymphoma that is Epstein-Barr virus positive remain uncertain as does the impact of congenital or iatrogenic immunosuppression. Patients with newly diagnosed diffuse large B-cell lymphoma with available tissue arrays were identified from the University of Iowa/Mayo Clinic Molecular Epidemiology Resource. Patients infected with human immunodeficiency virus or who had undergone a prior organ transplant were excluded. Epstein-Barr virus-associated ribonucleic acid testing was performed on all tissue arrays. A history of significant congenital or iatrogenic immunosuppression was determined for all patients. At enrollment, 16 of the 362 (4.4%) biopsies were positive for Epstein-Barr virus. Thirty-nine (10.8%) patients had a significant history of immunosuppression. Patients with Epstein-Barr-positive diffuse large B-cell lymphoma had no unique clinical characteristics but on pathology exhibited a higher frequency of CD30 positivity (25.0% versus 8.1%, respectively; P<0.01), and non-germinal-center subtype (62.5% versus 34.1%, respectively; P<0.01). No baseline clinical characteristics were associated with a history of immunosuppression. With a median follow up of 59 months, and after adjustment for International Prognostic Index, there was no association of Epstein-Barr virus positivity or immunosuppression with event-free survival at 24 months (odds ratio=0.49; 95% confidence interval: 0.13-1.84 and odds ratio=0.81; 95% confidence interval: 0.37-1.77) or overall survival (hazard ratio=0.86; 95% confidence interval: 0.38-1.97 and hazard ratio=1.00; 95% confidence interval: 0.57-1.74). In contrast to non-Western populations, our North American population had a low prevalence of Epstein-Barr virus-positive diffuse large B-cell lymphoma that did not convey an adverse prognosis. A history of immunosuppression, while known to be a risk factor for the development of diffuse large B-cell lymphoma, did not affect subsequent prognosis.

Fatal pulmonary embolism following splenectomy in a patient with Evan's syndrome: case report and review of the literature.

BACKGROUND: Evans syndrome (ES) is a rare disease characterized by simultaneous or sequential development of autoimmune hemolytic anemia (AIHA) and immune thrombocytopenia (ITP) with or without immune neutropenia. Splenectomy is one of the treatment options for disease refractory to medical therapy. Venous thromboembolism (VTE) following splenectomy for hematological diseases has an incidence of 10%. CASE PRESENTATION: Here we describe a case report of a young patient hospitalized with severe hemolytic anemia with Hgb 4.8 g/dl. He developed thrombocytopenia with platelet nadir of 52,000/mm3, thus formally diagnosed with ES. He failed standard medical therapy. He underwent splenectomy and had a fatal outcome. Autopsy confirmed the cause of death as pulmonary embolism (PE). CONCLUSIONS: This case report and review of the literature highlight important aspects of the association between VTE, splenectomy, and hemolytic syndromes including the presence of thrombocytopenia. The burden of the disease is reviewed as well as various pathophysiologic mechanisms contributing to thromboembolic events in these patients and current perioperative prophylactic anticoagulation strategies. Despite an advancing body of literature increasing awareness of VTE following splenectomy, morbidity and mortality remains high. Identifying high risk individuals for thromboembolic complications from splenectomy remains a challenge. There are no consensus guidelines for proper perioperative and post-operative anti-coagulation. We encourage future research to determine which factors might be playing a role in increasing the risk for VTE in real time with hope of forming a consensus to guide management.