Antithrombotic therapy in the management of hospitalised patients with COVID-19.

Hospitalised patients with coronavirus disease 2019 (COVID-19) are at a significantly higher risk of having thromboembolic events while in hospital and in the immediate post-hospital discharge period. Based on early data from observational studies, multiple high quality randomised controlled trials have been conducted worldwide to evaluate optimal thromboprophylaxis regimens to reduce thromboembolism and other COVID-19-related adverse outcomes in hospitalised patients. The International Society on Thrombosis and Haemostasis has published evidence-based guideline recommendations using established methodology for the management of antithrombotic therapy of COVID-19 patients, both in-hospital and in the immediate post-hospital discharge period. A good clinical practice statement supplemented these guidelines based on topics for which there was no or limited high-quality evidence. This review summarises the main recommendations of these documents to serve as a quick access tool for hospital doctors to use in their everyday practice when treating COVID-19 patients.

Integral assays of hemostasis in hospitalized patients with COVID-19 on admission and during heparin thromboprophylaxis.

BACKGROUND: Blood coagulation abnormalities play a major role in COVID-19 pathophysiology. However, the specific details of hypercoagulation and anticoagulation treatment require investigation. The aim of this study was to investigate the status of the coagulation system by means of integral and local clotting assays in COVID-19 patients on admission to the hospital and in hospitalized COVID-19 patients receiving heparin thromboprophylaxis. METHODS: Thrombodynamics (TD), thromboelastography (TEG), and standard clotting assays were performed in 153 COVID-19 patients observed in a hospital setting. All patients receiving treatment, except extracorporeal membrane oxygenation (ECMO) patients (n = 108), were administered therapeutic doses of low molecular weight heparin (LMWH) depending on body weight. The ECMO patients (n = 15) were administered unfractionated heparin (UFH). RESULTS: On admission, the patients (n = 30) had extreme hypercoagulation by all integral assays: TD showed hypercoagulation in ~75% of patients, while TEG showed hypercoagulation in ~50% of patients. The patients receiving treatment showed a significant heparin response based on TD; 77% of measurements were in the hypocoagulation range, 15% were normal, and 8% remained in hypercoagulation. TEG showed less of a response to heparin: 24% of measurements were in the hypocoagulation range, 59% were normal and 17% remained in hypercoagulation. While hypocoagulation is likely due to heparin treatment, remaining in significant hypercoagulation may indicate insufficient anticoagulation for some patients, which is in agreement with our clinical findings. There were 3 study patients with registered thrombosis episodes, and all were outside the target range for TD parameters typical for effective thromboprophylaxis (1 patient was in weak hypocoagulation, atypical for the LMWH dose used, and 2 patients remained in the hypercoagulation range despite therapeutic LMWH doses). CONCLUSION: Patients with COVID-19 have severe hypercoagulation, which persists in some patients receiving anticoagulation treatment, while significant hypocoagulation is observed in others. The data suggest critical issues of hemostasis balance in these patients and indicate the potential importance of integral assays in its control.

Major cardiovascular events after COVID-19, event rates post-vaccination, antiviral or anti-inflammatory therapy, and temporal trends: Rationale and methodology of the CORONA-VTE-Network study.

BACKGROUND: Coronavirus disease 2019 (COVID-19) is associated with excess risk of cardiovascular and thrombotic events in the early post-infection period and during convalescence. Despite the progress in our understanding of cardiovascular complications, uncertainty persists with respect to more recent event rates, temporal trends, association between vaccination status and outcomes, and findings within vulnerable subgroups such as older adults (aged 65 years or older), or those undergoing hemodialysis. Sex-informed findings, including results among pregnant and breastfeeding women, as well as adjusted comparisons between male and female adults are similarly understudied. METHODS: Adult patients, aged ≥18 years, with polymerase chain reaction-confirmed COVID-19 who received inpatient or outpatient care at the participating centers of the registry are eligible for inclusion. A total of 10,000 patients have been included in this multicenter study, with Brigham and Women's Hospital (Boston, MA) serving as the coordinating center. Other sites include Beth Israel Deaconess Medical Center, Anne Arundel Medical Center, University of Virginia Medical Center, University of Colorado Health System, and Thomas Jefferson University Health System. Data elements will be ascertained manually for accuracy. The two main outcomes are 1) a composite of venous or arterial thrombotic events, and 2) a composite of major cardiovascular events, defined as venous or arterial thrombosis, myocarditis or heart failure with inpatient treatment, new atrial fibrillation/flutter, or cardiovascular death. Clinical outcomes are adjudicated by independent physicians. Vaccination status and time of inclusion in the study will be ascertained for subgroup-specific analyses. Outcomes are pre-specified to be reported separately for hospitalized patients versus those who were initially receiving outpatient care. Outcomes will be reported at 30-day and 90-day follow-up. Data cleaning at the sites and the data coordinating center and outcomes adjudication process are in-progress. CONCLUSIONS: The CORONA-VTE-Network study will share contemporary information related to rates of cardiovascular and thrombotic events in patients with COVID-19 overall, as well as within key subgroups, including by time of inclusion, vaccination status, patients undergoing hemodialysis, the elderly, and sex-informed analyses such as comparison of women and men, or among pregnant and breastfeeding women.

Thrombosis Occurrence in COVID-19 Compared With Other Infectious Causes of ARDS: A Contemporary Cohort.

Thrombosis occurrence in coronavirus disease 2019 (COVID-19) has been mostly compared to historical cohorts of patients with other respiratory infections. We retrospectively evaluated the thrombotic events that occurred in a contemporary cohort of patients hospitalized between March and July 2020 for acute respiratory distress syndrome (ARDS) according to the Berlin Definition and compared those with positive and negative real-time polymerase chain reaction results for wild-type severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) using descriptive analysis. The association between COVID-19 and thrombotic risk was evaluated using logistic regression. 264 COVID-19-positive (56.8% male, 59.0 years [IQR 48.6-69.7], Padua score on admission 3.0 [2.0-3.0]) and 88 COVID-19-negative patients (58.0% male, 63.7 years [51.2-73.5], Padua score 3.0 [2.0-5.0]) were included. 10.2% of non-COVID-19 and 8.7% of COVID-19 patients presented ≥ 1 clinically relevant thrombotic event confirmed by imaging exam. After adjustment for sex, Padua score, intensive care unit stay, thromboprophylaxis, and hospitalization length, the odds ratio for thrombosis in COVID-19 was 0.69 (95% CI, 0.30-1.64). We, therefore, conclude that infection-induced ARDS carries an inherent thrombotic risk, which was comparable between patients with COVID-19 and other respiratory infections in our contemporary cohort.

Thromboprophylaxis for Coagulopathy Related to COVID-19 in Pediatrics: A Narrative Review.

In addition to harming the respiratory system, COVID-19 can affect multiple organs. Children may develop a specific complication of COVID-19 called multisystem inflammatory syndrome in children (MIS-C) which could influence the vascular system of children and cause multiple coagulopathies in the body. Information on the use of thromboprophylaxis in this condition was collected via the review of various articles. In general, different factors in immune system responses can trigger the initiation of thrombotic events. Studies have shown that starting anticoagulant prophylaxis, which contributes to decreased thrombotic events, is dependent on the patient's condition and D-dimer levels. However, further studies on pediatric populations are needed to establish the role of anticoagulants in children with this condition.

D-dimer testing: A narrative review.

D-dimer containing species are soluble fibrin degradation products derived from plasmin-mediated degradation of cross-linked fibrin, i.e., 'D-dimer'. D-dimer can hence be considered a biomarker of in vivo activation of both coagulation and fibrinolysis, the leading clinical application in daily practice of which is ruling out venous thromboembolism (VTE). D-dimer has been further evaluated for assessing the risk of VTE recurrence and helping define optimal duration of anticoagulation treatment in VTE, for diagnosing disseminated intravascular coagulation (DIC), and for screening those at enhanced risk of VTE. D-dimer assays should however be performed as intended by regulatory agencies, as their use outside these indications might make them a laboratory-developed test (LDT). This narrative review is aimed at: (1) reviewing the definition of D-dimer, (2) discussing preanalytical variables affecting D-dimer measurement, (3) reviewing and comparing the assays performance and some postanalytical variables (e.g., different units and age-adjusted cutoffs), and (4) discussing the interest of D-dimer measurement across different clinical settings, including pregnancy, cancer, and coronavirus disease 2019 (COVID-19).

A Literature Review of Pathophysiology, Clinical Manifestations, Medications and Optimal Dosage, Outpatient, and Post-hospitalization Use of Anticoagulation in COVID-19 Patients.

Since severe acute respiratory syndrome coronavirus 2 led to a world pandemic, extensive research has been conducted to identify its characteristics and form an appropriate management plan. One recognized complication of COVID-19 is coagulation defects that can lead to thromboembolic events. We have reviewed the literature to summarize and present the latest research about the pathophysiology, clinical manifestations, anticoagulation use and appropriate dose in COVID-19 patients, as well as the effect of anticoagulation in outpatient and post-hospital settings. The pathophysiology of coagulation abnormalities in COVID-19 is not fully understood yet, but multiple mechanisms appear to be involved, such as a direct viral attack, hyperinflammation, increased immune response, blood stasis, and endothelial injury. Clinical manifestations are mainly venous thromboembolism (deep vein thrombosis and pulmonary embolism), arterial thromboembolism, ischemic stroke, central venous sinus thrombosis, and central retinal vein occlusion. Anticoagulation is widely used in hospitalized patients with COVID-19, unless it is contraindicated. Heparinoid is the main anticoagulant used. However, the appropriate dosage is still debated as research is trying to find a balance between benefits and risks. In outpatients, it appears that anticoagulation has no benefit in contrast to post-hospitalization use, where benefit could be observed in severely affected patients. We concluded that thromboprophylaxis should be used in treating hospitalized COVID-19 patients, but the dosage is still a matter of debate. More research needs to be done on outpatient and post-hospitalized patients to derive accurate conclusions.

Efficacy and safety of two heparin regimens for prevention of venous thromboembolism in hospitalized patients with COVID-19: a meta-analysis.

Venous thromboembolism (VTE) is common in patients with coronavirus disease-2019 (COVID-19). The optimal heparin regimen remains unknown and should balance thromboembolic and bleeding risks. The aim of this study was to evaluate the efficacy and safety of standard or higher heparin regimens for the prevention of VTE in patients hospitalized due to COVID-19. We performed a systematic literature search; studies reporting on hospitalized patients with COVID-19 who received standard heparin prophylaxis vs. high (intermediate or therapeutic) heparin regimens were included if outcome events were reported by treatment group and more than 10 patients were included. Primary study outcome was in-hospital VTE. Secondary study outcomes were major bleeding (MB), all-cause death, fatal bleeding and fatal pulmonary embolism. Overall, 33 studies (11,387 patients) were included. Venous thromboembolic events occurred in 5.2% and in 8.2% of patients who received heparin prophylaxis with at high-dose or standard-dose, respectively (RR 0.71, 95% CI 0.55-0.90, I2 48.8%). MB was significantly higher in patients who received high- compared to the standard-dose (4.2% vs 2.2%, RR 1.94, 95% CI 1.47-2.56, I2 18.1%). Sub-analyses showed a slight benefit associated with high-dose heparin in patients admitted to non-intensive care unit (ICU) but not in those to ICU. No significant differences were observed for mortality outcomes. Heparin prophylaxis at high-dose reduces the risk of VTE, but increased the risk of MB compared to the standard-dose. No clinical benefit for heparin high-dose was observed for ICU setting, but its role in the non-ICU deserves further evaluation. PROSPERO registration number: CRD42021252550.

COVID-19 induced mesenteric ischemia in a patient with ulcerative colitis and paroxysmal nocturnal haemoglobinuria despite thromboprophylaxis.

Inflammatory bowel disease and paroxysmal nocturnal hemoglobinuria (PNH) are both well-known prothrombotic states. However, ongoing thromboprophylaxis is usually effective in such conditions. We report an imbalance that was triggered by COVID-19 infection. There is evidence that COVID-19 infection leads to thrombosis of vessels. The thrombosis of mesenteric vessels can be multifocal and without respiratory symptoms and leads to devastating consequences like resection of large segments of the bowel and lifelong requirement of parenteral nutritional support. We report about a case of ulcerative colitis (in remission) and PNH where COVID-19 resulted in mesenteric ischemia.

Prolonged Elevations of Factor VIII and von Willebrand Factor Antigen After Multisystem Inflammatory Syndrome in Children.

Multisystem Inflammatory Syndrome in Children (MIS-C) is a late systemic inflammatory response to a recent mild or asymptomatic coronavirus disease of 2019 infection. The pathophysiology is incompletely understood but it often features significant coagulopathy along with cardiac and endothelial dysfunction. Endothelial inflammation has been primarily described in acute coronavirus disease of 2019 infection, with less characterization in MIS-C. Here we describe novel findings of nearly universal severe and prolonged factor VIII (FVIII) and von Willebrand factor antigen elevations in an institutional cohort of patients with MIS-C ages younger than or 21 years old (N=31). All patients had elevated acute phase reactants and D-dimer at presentation and met published criteria for MIS-C. FVIII was high at presentation in 97% of patients but continued to rise during the ensuing weeks of treatment to a mean 429%, peaking on median day 17 of illness as an outpatient. FVIII levels were >600% in multiple patients. von Willebrand factor antigen was measured less frequently but showed similar trends. These escalations occurred amidst resolving cardiac dysfunction and acute phase reactant normalization and despite patients receiving multimodal anti-inflammatory treatments and aspirin and enoxaparin thromboprophylaxis. No thrombotic events occurred. Endothelial dysfunction represented by very elevated FVIII levels may persist longer than other acute phase reactants may reflect.

Management, control, and decision making in unexpected recurrent venous thromboembolism in COVID-19: a case report.

BACKGROUND: Coronavirus disease 2019 was spread worldwide, as a pandemic, from December 2019. Venous thromboembolism events can inflict patients with coronavirus disease 2019 during the hospitalization or convalescent period. Therefore, monitoring of these patients, in terms of venous thromboembolism events signs and symptoms, and timely management of antithrombotic agents are of great importance. CASE REPORT: A 45-year-old Iranian man, who is the first author of this case report, was infected by severe acute respiratory syndrome coronavirus 2 and displayed the typical signs and symptoms of coronavirus disease 2019. Although reverse transcription polymerase chain reaction for coronavirus disease 2019, and specific immunoglobulin M and immunoglobulin G against severe acute respiratory syndrome coronavirus 2, were negative at first, chest computed tomography scan showed the characteristic pattern of lung involvement of a coronavirus disease 2019 infection including bilateral and multilobar ground-glass opacities. At that time, there were no signs or symptoms of deep-vein thrombosis or pulmonary thromboembolism, so these were not investigated. About 30 hours after hospital discharge, the patient presented back to the hospital with acute-onset chest pain. We instantly tested his blood for D-dimer, and sent him to take a Doppler sonography of his lower legs and a chest computed tomography angiography in search of pulmonary thromboembolism and deep-vein thrombosis. Although we could confirm pulmonary thromboembolism with computed tomography angiography in our patient, there were no signs or symptoms of venous thromboembolism in his lower legs, and color Doppler sonography of lower limbs was normal. So, the patient was treated with rivaroxaban as an antithrombotic agent. After some days, he was discharged in good condition. About 1 month later, he was referred to our hospital because of left lower limb edema. Although he was under antithrombotic therapy, color Doppler sonography of lower limbs revealed acute deep-vein thrombosis of the left leg. Hence, we decided to shift antithrombotic therapy from rivaroxaban to warfarin, as it is more potent than rivaroxaban in recurrent venous thromboembolism and when taking new oral anticoagulants. Unlike rivaroxaban, which needs no blood test to monitor its efficacy but has a warning for signs and symptoms of bleeding, warfarin therapy must be monitored carefully by regular blood tests for prothrombin time and international normalized ratio to maintain them in the therapeutic range. The patient was informed about the bleeding cautions, and required regular check of prothrombin time and international normalized ratio to maintain them in the proper and advised range of treatment (international normalized ratio therapeutic range 2-3). CONCLUSION: In the case of unexpected recurrent venous thromboembolism in coronavirus disease 2019, especially when patients are taking rivaroxaban or other new oral anticoagulants, such drugs should be substituted by warfarin, with routine follow-up, to maintain the value of prothrombin time and international normalized ratio within the therapeutic range.

COVID-19-associated coagulopathy in children: A multicenter observational cohort study.

SARS-CoV-2 infection (coronavirus disease 2019 [COVID-19]) induces a stark procoagulant state, with many hospitalized adults developing thrombosis despite prophylactic anticoagulation. This study aimed to characterize hemostatic parameters and associated clinical outcomes of COVID-19, such as thrombosis and bleeding, in children and to assess thromboprophylaxis use. This multicenter observational cohort study included 79 patients aged up to 18 years admitted to all pediatric hospitals in Québec, Canada, with SARS-CoV-2 infection during a 5-month period. D-dimers were elevated in 18/19 patients (94.7%) and fibrinogen in 15/26 patients (60%). Eleven patients (13.9%) received anticoagulant thromboprophylaxis. One thrombotic event and one major bleed were observed.

Effect of Thromboprophylaxis on Clinical Outcomes After COVID-19 Hospitalization.

BACKGROUND: Patients hospitalized with COVID-19 have an increased incidence of thromboembolism. The role of extended thromboprophylaxis after hospital discharge is unclear. OBJECTIVE: To determine whether anticoagulation is superior to placebo in reducing death and thromboembolic complications among patients discharged after COVID-19 hospitalization. DESIGN: Prospective, randomized, double-blind, placebo-controlled clinical trial. (ClinicalTrials.gov: NCT04650087). SETTING: Done during 2021 to 2022 among 127 U.S. hospitals. PARTICIPANTS: Adults aged 18 years or older hospitalized with COVID-19 for 48 hours or more and ready for discharge, excluding those with a requirement for, or contraindication to, anticoagulation. INTERVENTION: 2.5 mg of apixaban versus placebo twice daily for 30 days. MEASUREMENTS: The primary efficacy end point was a 30-day composite of death, arterial thromboembolism, and venous thromboembolism. The primary safety end points were 30-day major bleeding and clinically relevant nonmajor bleeding. RESULTS: Enrollment was terminated early, after 1217 participants were randomly assigned, because of a lower than anticipated event rate and a declining rate of COVID-19 hospitalizations. Median age was 54 years, 50.4% were women, 26.5% were Black, and 16.7% were Hispanic; 30.7% had a World Health Organization severity score of 5 or greater, and 11.0% had an International Medical Prevention Registry on Venous Thromboembolism risk prediction score of greater than 4. Incidence of the primary end point was 2.13% (95% CI, 1.14 to 3.62) in the apixaban group and 2.31% (CI, 1.27 to 3.84) in the placebo group. Major bleeding occurred in 2 (0.4%) and 1 (0.2%) and clinically relevant nonmajor bleeding occurred in 3 (0.6%) and 6 (1.1%) apixaban-treated and placebo-treated participants, respectively. By day 30, thirty-six (3.0%) participants were lost to follow-up, and 8.5% of apixaban and 11.9% of placebo participants permanently discontinued the study drug treatment. LIMITATIONS: The introduction of SARS-CoV-2 vaccines decreased the risk for hospitalization and death. Study enrollment spanned the peaks of the Delta and Omicron variants in the United States, which influenced illness severity. CONCLUSION: The incidence of death or thromboembolism was low in this cohort of patients discharged after hospitalization with COVID-19. Because of early enrollment termination, the results were imprecise and the study was inconclusive. PRIMARY FUNDING SOURCE: National Institutes of Health.

Pharmacology and Clinical Development of Factor XI Inhibitors.

Therapeutic anticoagulation is indicated for a variety of circumstances and conditions in several fields of medicine to prevent or treat venous and arterial thromboembolism. According to the different mechanisms of action, the available parenteral and oral anticoagulant drugs share the common principle of hampering or blocking key steps of the coagulation cascade, which unavoidably comes at the price of an increased propensity to bleed. Hemorrhagic complications affect patient prognosis both directly and indirectly (ie, by preventing the adoption of an effective antithrombotic strategy). Inhibition of factor XI (FXI) has emerged as a strategy with the potential to uncouple the pharmacological effect and the adverse events of anticoagulant therapy. This observation is based on the differential contribution of FXI to thrombus amplification, in which it plays a major role, and hemostasis, in which it plays an ancillary role in final clot consolidation. Several agents were developed to inhibit FXI at different stages (ie, suppressing biosynthesis, preventing zymogen activation, or impeding the biological action of the active form), including antisense oligonucleotides, monoclonal antibodies, small synthetic molecules, natural peptides, and aptamers. Phase 2 studies of different classes of FXI inhibitors in orthopedic surgery suggested that dose-dependent reductions in thrombotic complications are not paralleled by dose-dependent increases in bleeding compared with low-molecular-weight heparin. Likewise, the FXI inhibitor asundexian was associated with lower rates of bleeding compared with the activated factor X inhibitor apixaban in patients with atrial fibrillation, although no evidence of a therapeutic effect on stroke prevention is available so far. FXI inhibition could also be appealing for patients with other conditions, including end-stage renal disease, noncardioembolic stroke, or acute myocardial infarction, for which other phase 2 studies have been conducted. The balance between thromboprophylaxis and bleeding achieved by FXI inhibitors needs confirmation in large-scale phase 3 clinical trials powered for clinical end points. Several of such trials are ongoing or planned to define the role of FXI inhibitors in clinical practice and to clarify which FXI inhibitor may be most suited for each clinical indication. This article reviews the rationale, pharmacology, results of medium or small phase 2 studies, and future perspectives of drugs inhibiting FXI.

EFFECTS OF SARS COVID-19 POSITIVITY STATUS ON VENOUS THROMBOSIS AND PULMONARY EMBOLISM RATES IN TRAUMA PATIENTS.

ABSTRACT: Introduction : COVID-19-induced coagulopathy (CIC) can increase the risk of thromboembolism without underlying clotting disorders, even when compared with other respiratory viruses. Trauma has a known association with hypercoagulability. Trauma patients with concurrent COVID-19 infection potentially have an even greater risk of thrombotic events. The purpose of this study was to evaluate venous thromboembolism (VTE) rates in trauma patients with COVID-19. Methods : This study reviewed all adult patients (≥18 years of age) admitted to the Trauma Service from April through November 2020 for a minimum of 48 hours. Patients were grouped based off COVID-19 status and compared for inpatient VTE chemoprophylaxis regimen, thrombotic complications defined as deep vein thrombosis, pulmonary embolism, myocardial infarction, and cerebrovascular accident, intensive care unit (ICU) length of stay, hospital length of stay, and mortality. Results : A total of 2,907 patients were reviewed and grouped into COVID-19-positive (n = 110) and COVID-19-negative (n = 2,797) groups. There was no difference in terms of receiving deep vein thrombosis chemoprophylaxis or type, but a longer time to initiation in the positive group ( P = 0.0012). VTE occurred in 5 (4.55%) positive and 60 (2.15%) negative patients without a significant difference between the groups, as well as no difference in type of VTE observed. Mortality was higher ( P = 0.009) in the positive group (10.91%). Positive patients had longer median ICU LOS ( P = 0.0012) and total LOS ( P < 0.001). Conclusion : There were no increased rates of VTE complications between COVID-19-positive and -negative trauma patients, despite a longer time to initiation of chemoprophylaxis in the COVID-19-positive group. COVID-19-positive patients had increased ICU LOS, total LOS, and mortality, which are likely due to multifactorial causes but primarily related to their underlying COVID-19 infection.

External validation of the ADA score for predicting thrombosis among acutely ill hospitalized medical patients from the APEX Trial.

The ADA (Age-D-dimer-Albumin) score was developed to identify hospitalized patients at an increased risk for thrombosis in the coronavirus infectious disease-19 (COVID-19) setting. The study aimed to validate the ADA score for predicting thrombosis in a non-COVID-19 medically ill population from the APEX trial. The APEX trial was a multinational, randomized trial that evaluated the efficacy and safety of betrixaban vs. enoxaparin among acutely ill hospitalized patients at risk for venous thromboembolism. The study endpoints included the composite of arterial or venous thrombosis and its components. Metrics of model calibration and discrimination were computed for assessing the performance of the ADA score as compared to the IMPROVE score, a well-validated VTE risk assessment model. Among 7,119 medical inpatients, 209 (2.9%) had a thrombosis event up to 77 days of follow-up. The ADA score demonstrated good calibration for both arterial and venous thrombosis, whereas the IMPROVE score had adequate calibration for venous thrombosis (p > 0.05 from the Hosmer-Lemeshow test). For discriminating arterial and venous thrombosis, there was no significant difference between the ADA vs. IMPROVE score (c statistic = 0.620 [95% CI: 0.582 to 0.657] vs. 0.590 [95% CI: 0.556 to 0.624]; ∆ c statistic = 0.030 [95% CI: -0.022 to 0.081]; p = 0.255). Similarly, for discriminating arterial thrombosis, there was no significant difference between the ADA vs. IMPROVE score (c statistic = 0.582 [95% CI: 0.534 to 0.629] vs. 0.609 [95% CI: 0.564 to 0.653]; ∆ c statistic = -0.027 [95% CI: -0.091 to 0.036]; p = 0.397). For discriminating venous thrombosis, the ADA score was modestly superior to the IMPROVE score (c statistic = 0.664 [95% CI: 0.607 to 0.722] vs. 0.573 [95% CI: 0.521 to 0.624]; ∆ c statistic = 0.091 [95% CI: 0.011 to 0.172]; p = 0.026). The ADA score had a higher sensitivity (0.579 [95% CI: 0.512 to 0.646]; vs. 0.440 [95% CI: 0.373 to 0.507]) but lower specificity (0.625 [95% CI: 0.614 to 0.637] vs. 0.747 [95% CI: 0.737 to 0.758]) than the IMPROVE score for predicting thrombosis. Among acutely ill hospitalized medical patients enrolled in the APEX trial, the ADA score demonstrated good calibration but suboptimal discrimination for predicting thrombosis. The findings support the use of either the ADA or IMPROVE score for thrombosis risk assessment. The applicability of the ADA score to non-COVID-19 populations warrants further research.Clinical Trial Registration: http://www.clinicaltrials.gov . Unique identifier: NCT01583218.

The Effectiveness of the Intermediate and Therapeutic Doses of Enoxaparin in COVID-19 Patients: A Comparative Study of Factor Xa Inhibition.

BACKGROUND: Management of anticoagulant therapy in COVID-19 patients is critical. Low-molecular-weight heparin (LMWH) thromboprophylaxis is already recommended, and anti-Factor Xa (anti-FXa) monitoring has been used to titrate LMWH doses. METHODS: Through a cross-sectional study, we evaluated anti-FXa activity in patients admitted to the ICU, receiving intermediate dose (30, 40, 50 mg, subcutaneously [SC], twice daily) or therapeutic dose (1 mg/kg, SC, Q12h) of enoxaparin to find whether the patients in these two groups achieved anti-FXa levels in the accepted thromboprophylaxis range. RESULTS: The occurrence of deep vein thrombosis was 26% in the therapeutic-dose group and 17% in the intermediate-dose group. D-dimer values were nearly 3.5-fold higher in those who received a therapeutic dose of anticoagulants than in those who received intermediate-dose thromboprophylaxis. Patients in the therapeutic-dose group had significantly higher IL-6 levels (p ≤ 0.001). More than one-third of the patients in the therapeutic-dose group (n = 8; 42.18%) and approximately half of the patients in the intermediate-dose group (n = 12; 52.2%) achieved the target range level of anti-FXa. Patients who received therapeutic doses were more likely to have anti-FXa levels above the expected range (47.4 vs 13% in the intermediate-dose group; p < 0.05). CONCLUSION: Therapeutic dose of enoxaparin in critically ill COVID-19-infected patients did not reduce the incidence of thromboembolic events and, on the other hand, may predispose these patients to increased risk of bleeding by increasing anti-FXa activity above the desired level. Administration of intermediate-dose thromboprophylaxis is suggested to achieve anti-FXa levels in the accepted thromboprophylaxis range.

[Thromboprophylaxis and management of anticoagulation in hospitalized patients with COVID-19: clinical pathway and practices].

Inpatients infected with SARS-CoV-2 are prone to various complications during clinical treatment, especially venous thromboembolism (VTE), which significantly increases the risk of unexpected death. In recent years, a series of authoritative guidelines and high-quality evidence-based medicine research evidence have been published internationally. This working group has recently formulated the Guidelines for Thrombosis Prevention and Anticoagulant Management of Hospitalized Patients with Novel Coronavirus Infection with multidisciplinary experts in the fields of VTE prevention, critical care and evidence-based medicine from international and domestic experts. Based on this, the working group elaborated on 13 clinical issues in urgent need of attention and solution in current clinical practice on the basis of the guidelines and defined standardized operational paths, including VTE risk and bleeding risk assessment in hospitalized patients with COVID-19, VTE prevention and anticoagulant management of hospitalized COVID-19 patients with different severity and special patient populations complicated with pregnancy, malignant tumors, underlying diseases or organ insufficiency, usage of antiviral and anti-inflammatory drugs or thrombocytopenia, in addition to VTE prevention and anticoagulant management of discharged COVID-19 patients, anticoagulant management of COVID-19 patients complicated with VTE during hospitalization, anticoagulant management in patients undergoing VTE therapy with COVID-19, risk factors of bleeding in hospitalized patients with COVID-19, clinical classification and corresponding management. In particular, by referring to the latest international guidelines and research evidence, this paper provides clear implementation recommendations on how to accurately determine the standard preventive dose anticoagulation and therapeutic dose anticoagulation for hospitalized patients with COVID-19. This paper is expected to provide standardized operational procedures and implementation norms for healthcare workers to managing thrombus prevention and anticoagulation in hospitalized patients with COVID-19.