Objective To evaluate the effects of therapeutic heparin compared with prophylactic heparin among moderately ill patients with covid-19 admitted to hospital wards. Design Randomised controlled, adaptive, open label clinical trial. Setting 28 hospitals in Brazil, Canada, Ireland, Saudi Arabia, United Arab Emirates, and US. Participants 465 adults admitted to hospital wards with covid-19 and increased D-dimer levels were recruited between 29 May 2020 and 12 April 2021 and were randomly assigned to therapeutic dose heparin (n=228) or prophylactic dose heparin (n=237). Interventions Therapeutic dose or prophylactic dose heparin (low molecular weight or unfractionated heparin), to be continued until hospital discharge, day 28, or death. Main outcome measures The primary outcome was a composite of death, invasive mechanical ventilation, non-invasive mechanical ventilation, or admission to an intensive care unit, assessed up to 28 days. The secondary outcomes included all cause death, the composite of all cause death or any mechanical ventilation, and venous thromboembolism. Safety outcomes included major bleeding. Outcomes were blindly adjudicated. Results The mean age of participants was 60 years; 264 (56.8%) were men and the mean body mass index was 30.3 kg/m 2 . At 28 days, the primary composite outcome had occurred in 37/228 patients (16.2%) assigned to therapeutic heparin and 52/237 (21.9%) assigned to prophylactic heparin (odds ratio 0.69, 95% confidence interval 0.43 to 1.10; P=0.12). Deaths occurred in four patients (1.8%) assigned to therapeutic heparin and 18 patients (7.6%) assigned to prophylactic heparin (0.22, 0.07 to 0.65; P=0.006). The composite of all cause death or any mechanical ventilation occurred in 23 patients (10.1%) assigned to therapeutic heparin and 38 (16.0%) assigned to prophylactic heparin (0.59, 0.34 to 1.02; P=0.06). Venous thromboembolism occurred in two patients (0.9%) assigned to therapeutic heparin and six (2.5%) assigned to prophylactic heparin (0.34, 0.07 to 1.71; P=0.19). Major bleeding occurred in two patients (0.9%) assigned to therapeutic heparin and four (1.7%) assigned to prophylactic heparin (0.52, 0.09 to 2.85; P=0.69). Conclusions In moderately ill patients with covid-19 and increased D-dimer levels admitted to hospital wards, therapeutic heparin was not significantly associated with a reduction in the primary outcome but the odds of death at 28 days was decreased. The risk of major bleeding appeared low in this trial. Trial registration ClinicalTrials.gov NCT04362085 .

Endothelial injury and microvascular/macrovascular thrombosis are common pathophysiological features of coronavirus disease-2019 (COVID-19). However, the optimal thromboprophylactic regimens remain unknown across the spectrum of illness severity of COVID-19. A variety of antithrombotic agents, doses, and durations of therapy are being assessed in ongoing randomized controlled trials (RCTs) that focus on outpatients, hospitalized patients in medical wards, and patients critically ill with COVID-19. This paper provides a perspective of the ongoing or completed RCTs related to antithrombotic strategies used in COVID-19, the opportunities and challenges for the clinical trial enterprise, and areas of existing knowledge, as well as data gaps that may motivate the design of future RCTs.

IMPORTANCEAcutely ill inpatients with COVID-19 typically receive antithrombotic therapy, although the risks and benefits of this intervention among outpatients with COVID-19 have not been established. OBJECTIVE To assess whether anticoagulant or antiplatelet therapy can safely reduce major adverse cardiopulmonary outcomes among symptomatic but clinically stable outpatients with COVID-19. DESIGN, SETTING, AND PARTICIPANTSThe ACTIV-4B Outpatient Thrombosis Prevention Trial was designed as a minimal-contact, adaptive, randomized, double-blind, placebo-controlled trial to compare anticoagulant and antiplatelet therapy among 7000 symptomatic but clinically stable outpatients with COVID-19. The trial was conducted at 52 US sites between September 2020 and June 2021; final follow-up was August 5, 2021. Prior to initiating treatment, participants were required to have platelet count greater than 100 000/mm 3 and estimated glomerular filtration rate greater than 30 mL/min/1.73 m 2 .INTERVENTIONS Random allocation in a 1:1:1:1 ratio to aspirin (81 mg orally once daily; n = 164), prophylactic-dose apixaban (2.5 mg orally twice daily; n = 165), therapeutic-dose apixaban (5 mg orally twice daily; n = 164), or placebo (n = 164) for 45 days. MAIN OUTCOMES AND MEASURESThe primary end point was a composite of all-cause mortality, symptomatic venous or arterial thromboembolism, myocardial infarction, stroke, or hospitalization for cardiovascular or pulmonary cause. The primary analyses for efficacy and bleeding events were limited to participants who took at least 1 dose of trial medication. RESULTSOn June 18, 2021, the trial data and safety monitoring board recommended early terminationbecauseoflowerthananticipatedeventrates;atthattime,657symptomaticoutpatients with COVID-19 had been randomized (median age, 54 years [IQR,[46][47][48][49][50][51][52][53][54][55][56][57][58][59]; 59% women). The median times from diagnosis to randomization and from randomization to initiation of study treatment were 7 days and 3 days, respectively. Twenty-two randomized participants (3.3%) were hospitalized for COVID-19 prior to initiating treatment. Among the 558 patients who initiated treatment, the adjudicated primary composite end point occurred in 1 patient (0.7%) in the aspirin group, 1 patient (0.7%) in the 2.5-mg apixaban group, 2 patients (1.4%) in the 5-mg apixaban group, and 1 patient (0.7%) in the placebo group. The risk differences compared with placebo for the primary end point were 0.0% (95% CI not calculable) in the aspirin group, 0.7% (95% CI, -2.1% to 4.1%) in the 2.5-mg apixaban group, and 1.4% (95% CI, -1.5% to 5.0%) in the 5-mg apixaban group. Risk differences compared with placebo for bleeding events were 2.0% (95% CI, -2.7% to 6.8%), 4.5% (95% CI, -0.7% to 10.2%), and 6.9% (95% CI, 1.4% to 12.9%) among participants who initiated therapy in the aspirin, prophylactic apixaban, and therapeutic apixaban groups, respectively, although none were major. Findings inclusive of all randomized patients were similar.CONCLUSIONS AND RELEV...

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 Study acronym or PI Trial ID Source registry Countries Date of registration Estimated study completion date COVID-HEP NCT04345848 ClinicalTrials.gov Switzerland

About 20%-55% of patients admitted to hospital for coronavirus disease 2019 (COVID-19) have laboratory evidence of coagulopathyCoagulopathy correlates with severity of COVID-19 and may include increased d-dimer concentrations (≥ 2 times above normal range), mildly prolonged prothrombin time (~ 1-3 s prolongation above normal range), mild thrombocytopenia (platelet count > 100 ×10 9 /L) and, in late disease, decreased fibrinogen levels (< 2 g/L [5.88 µmol/L]). 1-3 It is uncertain whether the observed coagulopathy is caused directly by the virus or is secondary to a proinflammatory state. Elevated d-dimer concentration is associated with poor clinical outcomesIt is unclear how a d-dimer result should specifically be used in clinical care. However, an increased concentration at the time of hospital admission and throughout the hospital stay is associated with death, 1,2 and a concentration 4 times above normal is associated with an approximately fivefold higher odds of critical illness than a normal d-dimer concentration (www.medrxiv.org/content/ In the absence of a contraindication, patients admitted to hospital should receive venous thromboembolism prophylaxis as per standard of careVenous thromboembolism prophylaxis is recommended for most admitted patients, especially those with a proinflammatory state. In 1 retrospective study, patients with a d-dimer concentration 6 times above normal who received heparin thromboprophylaxis (mostly enoxaparin 40-60 mg/d) had lower mortality than those who did not receive thromboprophylaxis. 6 Transfusion of blood products should be avoided in patients who do not have active, major bleedingTransfusing with the aim of correcting only hemostatic laboratory parameters can be harmful (e.g., risk of transfusion reaction), regardless of whether the patient has COVID-19. Patients with active, major bleeding should be transfused appropriately as per local protocol.

Introduction: A recombinant porcine factor VIII B-domain-deleted product (rpFVIII; OBIZUR, Baxalta Incorporated, Deerfield, IL 60015, USA) was recently approved for treatment of bleeding episodes in adults with acquired haemophilia A (AHA) in the United States. To date, no clinical experience outside the registration study has been reported. Aim: To describe early clinical experience using rpFVIII for AHA. Methods: A retrospective chart review of seven patients with AHA treated with rpFVIII at four institutions from November 2014 to October 2015. Results: The time to diagnosis of AHA ranged from 5 days to 6 weeks. Six major and one other bleed were treated with rpFVIII following unsatisfactory bypassing agent (BPA) therapy. Good haemostatic efficacy was seen in five of seven cases. rpFVIII loading doses of 100 (n = 6) or 200 U kg À1 (n = 1) increased FVIII activity from <1 to 9% at baseline to 109-650% within 0.25-7 h in six of seven cases. Subsequent median doses ranged from 30 to 100 U kg À1 for 3-26 days. No rpFVIII-related adverse events were reported. Three patients survived with inhibitor eradication, one with persistent inhibitor, two died with inhibitors present and one was discharged and later died from unrelated causes. Conclusions: rpFVIII showed good haemostatic efficacy with no recurrences in most cases, with consumption substantially less than in the registration study. Treatment decisions were based on FVIII activity levels and clinical assessment. The ability to titrate rpFVIII dose using FVIII activity was considered advantageous compared with BPA therapy. Notable delays in diagnosis were observed.

Novel oral anticoagulants (NOACs) (rivaroxaban, dabigatran, apixaban) have been approved by international regulatory agencies to treat atrial fibrillation and venous thromboembolism in patients with kidney dysfunction. However, altered metabolism of these drugs in the setting of impaired kidney function may subject patients with CKD to alterations in their efficacy and a higher risk of bleeding. This article examined the efficacy and safety of the NOACs versus vitamin K antagonists (VKAs) for atrial fibrillation and venous thromboembolism in patients with CKD. A systematic review and meta-analyses of randomized controlled trials were conducted to estimate relative risk (RR) with 95% confidence interval (95% CIs) using a random-effects model. MEDLINE, Embase, and the Cochrane Library were searched to identify articles published up to March 2013. We selected published randomized controlled trials of NOACs compared with VKAs of at least 4 weeks' duration that enrolled patients with CKD (defined as creatinine clearance of 30-50 ml/min) and reported data on comparative efficacy and bleeding events. Eight randomized controlled trials were eligible. There was no significant difference in the primary efficacy outcomes of stroke and systemic thromboembolism (four trials, 9693 participants; RR, 0.64 [95% CI, 0.39 to 1.04]) and recurrent thromboembolism or thromboembolism-related death (four trials, 891 participants; RR, 0.97 [95% CI, 0.43 to 2.15]) with NOACs versus VKAs. The risk of major bleeding or the combined endpoint of major bleeding or clinically relevant nonmajor bleeding (primary safety outcome) (eight trials, 10,616 participants; RR 0.89 [95% CI, 0.68 to 1.16]) was similar between the groups. The use of NOACs in select patients with CKD demonstrates efficacy and safety similar to those with VKAs. Proactive postmarketing surveillance and further studies are pivotal to further define the rational use of these agents.

Background Pulmonary endothelial injury and microcirculatory thromboses likely contribute to hypoxemic respiratory failure, the most common cause of death, in patients with COVID‐19. Randomized controlled trials (RCTs) suggest differences in the effect of therapeutic heparin between moderately and severely ill patients with COVID‐19. We did a systematic review and meta‐analysis of RCTs to determine the effects of therapeutic heparin in hospitalized patients with COVID‐19. Methods We searched PubMed, Embase, Web of Science, medRxiv, and medical conference proceedings for RCTs comparing therapeutic heparin with usual care, excluding trials that used oral anticoagulation or intermediate doses of heparin in the experimental arm. Mantel‐Haenszel fixed‐effect meta‐analysis was used to combine odds ratios (ORs). Results and Conclusions There were 3 RCTs that compared therapeutic heparin to lower doses of heparin in 2854 moderately ill ward patients, and 3 RCTs in 1191 severely ill patients receiving critical care. In moderately ill patients, there was a nonsignificant reduction in all‐cause death (OR, 0.76; 95% CI, 0.57‐1.02), but significant reductions in the composite of death or invasive mechanical ventilation (OR, 0.77; 95% CI, 0.60 0.98), and death or any thrombotic event (OR, 0.58; 95% CI, 0.45‐0.77). Organ support‐free days alive (OR, 1.29; 95% CI, 1.07‐1.57) were significantly increased with therapeutic heparin. There was a nonsignificant increase in major bleeding. In severely ill patients, there was no evidence for benefit of therapeutic heparin, with significant treatment‐by‐subgroup interactions with illness severity for all‐cause death ( P = .034). In conclusion, therapeutic heparin is beneficial in moderately ill patients but not in severely ill patients hospitalized with COVID‐19.