Plantar vein thrombosis: 17-year longitudinal study of consecutive patients from a Swiss academic center.

Background: Plantar vein thrombosis (PVT) is a rare condition. Less than 50 cases have been described in the literature. Evidence from interventional and observational studies is sparse or lacking. Objectives: To describe a consecutive cohort of patients diagnosed with PVT at a single academic institution over the past 17 years. Methods: We searched medical charts from patients managed at the University Hospital Zurich between 2005 and 2022. PVT was detected through sonography (eg, in the presence of a noncompressible deep vein) and/or magnetic resonance (eg, a vein with a filling defect on non-contrast-enhanced or contrast-enhanced imaging). The study was approved by the local ethics commission. Results: We identified 45 patients who had been assessed for PVT. After manual check of these cases, we selected 16 patients with a confirmed, objective diagnosis. Median age was 62 (25th-75th percentiles, 46-73) years, and 9 (56%) patients were women. All patients were symptomatic, usually reporting local pain in the foot (100%) and swelling (67%). The most frequent risk factors were cancer (n = 6; 38%) and prior deep vein thrombosis (n = 4; 25%). Overall, 80% of patients received oral anticoagulation and 20% received parenteral anticoagulation for a median of 90 days. Over a median follow-up of 17 months, 2 (12.5%) recurrent venous thromboembolism events were recorded following the discontinuation of anticoagulation. Index vein recanalization occurred in all 15 survivors. One patient died from cancer 2 years after PVT diagnosis. Conclusion: We provided initial information on the clinical characteristics, treatment, and course of PVT, which partly resembles that of distal deep vein thrombosis.

Drivers and recent trends of hospitalisation costs related to acute pulmonary embolism.

BACKGROUND AND AIMS: The socio-economic burden imposed by acute pulmonary embolism (PE) on European healthcare systems is largely unknown. We sought to determine temporal trends and identify cost drivers of hospitalisation for PE in Germany. METHODS AND RESULTS: We analysed the totality of reimbursed hospitalisation costs in Germany (G-DRG system) in the years 2016-2020. Overall, 484 884 PE hospitalisations were coded in this period. Direct hospital costs amounted to a median of 3572 (IQR, 2804 to 5869) euros, resulting in average total reimbursements of 710 million euros annually. Age, PE severity, comorbidities and in-hospital (particularly bleeding) complications were identified by multivariable logistic regression as significant cost drivers. Use of catheter-directed therapy (CDT) constantly increased (annual change in the absolute proportion of hospitalisations with CDT + 0.40% [95% CI + 0.32% to + 0.47%]; P < 0.001), and it more than doubled in the group of patients with severe PE (28% of the entire population) over time. Although CDT use was overall associated with increased hospitalisation costs, this association was no longer present (adjusted OR 1.02 [0.80-1.31]) in patients with severe PE and shock; this was related, at least in part, to a reduction in the median length of hospital stay (for 14.0 to 8.0 days). CONCLUSIONS: We identified current and emerging cost drivers of hospitalisation for PE, focusing on severe disease and intermediate/high risk of an adverse early outcome. The present study may inform reimbursement decisions by policymakers and help to guide future health economic analysis of advanced treatment options for patients with PE.

Applying a Computer-based Warfarin Management System at a Large Tertiary Cardiovascular Center in Iran.

BACKGROUND: Regarding adjustments to warfarin dosage, numerous studies have shown that computerized methods are superior to those based on personal experience. OBJECTIVES: To report the efficacy of a computer-based warfarin management system (WMS) in the Iranian population. METHODS: By utilizing the existing dosing algorithms and obtaining expert opinions, we developed a computer-based WMS at a large tertiary cardiovascular center. The time in therapeutic range (TTR) and the number of international normalized ratio (INR) tests of clinic patients were compared before and after the implementation of WMS. RESULTS: Overall, 803 patients with 5407 INR tests were included in the before phase and 679 patients with 4189 INR tests in the after phase. The mean TTR was 57.3% before and 59% after WMS implementation (mean difference, 1.64, 95% CI: -1.12 to 4.40). In the before phase, the mean number of INR tests was 6.7, which dropped to 6.1 tests in the after phase (mean difference, -0.61, 95% CI: -0.97 to -0.24). Only 54.5% of the warfarin dosing prescriptions were consistent with the dosing recommendations of the WMS, and adherence to the WMS was poorest in the highest INR target range. CONCLUSIONS: For the first time in Iran, we demonstrated that a computerized system was as effective as a traditional experience-based method to monitor INR in VKA-anticoagulated patients. Furthermore, it could reduce both the number of INR tests and that of visits.

Unmet needs and barriers in venous thromboembolism education and awareness among people living with cancer: a global survey.

BACKGROUND: Venous thromboembolism (VTE) is a major preventable cause of morbidity, disability, and mortality in subjects with cancer. A global appraisal of cancer-associated VTE education and awareness is not available. OBJECTIVES: To evaluate VTE-related education, awareness, and unmet needs from the perspective of people living with cancer using a quantitative and qualitative approach. METHODS: This cross-sectional study used data from an online-based survey covering multidimensional domains of cancer-associated VTE. Data are presented descriptively. Potential differences across participant subgroups were explored. RESULTS: Among 2262 patients with cancer from 42 countries worldwide, 55.3% received no VTE education throughout their cancer journey, and an additional 8.2% received education at the time of VTE diagnosis only, leading to 63.5% receiving no or inappropriately delayed education. When education was delivered, only 67.8% received instructions to seek medical attention in case of VTE suspicion, and 36.9% reported scarce understanding. One-third of participants (32.4%) felt psychologically distressed when becoming aware of the potential risks and implications connected with cancer-associated VTE. Most responders (78.8%) deemed VTE awareness highly relevant, but almost half expressed concerns about the quality of education received. While overall consistent, findings in selected survey domains appeared to numerically differ across age group, ethnicity, continent of residence, educational level, metastatic status, and VTE history. CONCLUSION: This study involving a large and diverse population of individuals living with cancer identifies important unmet needs in VTE-related education, awareness, and support across healthcare systems globally. These findings unveil multilevel opportunities to expedite patient-centered care in cancer-associated VTE prevention and management.

Mortality trend of ischemic heart disease (2008-2022): A retrospective analysis of epidemiological data.

BACKGROUND: Age-sex specific trend analyses of ischemic heart disease (IHD)-related mortality and prevalent risk factors can improve our understanding and approach to the disease. METHODS: We performed a 15-year retrospective epidemiological analysis of acute and chronic IHD-related mortality and prevalent cardiovascular risk factors using administrative data from Veneto, a socio-economically homogeneous Italian region. Standard mortality statistics using the underlying cause of death (UCOD) and deaths with any mention of IHD in death certificates (MCOD) from ICD-10 codes I20-I25 was performed between 2008 and 2022. RESULTS: A total of 134,327 death certificates reported IHD-related deaths, representing 18.6% of all deaths. Proportional mortality decreased from 14.6% in 2008 to 7.8% in 2022 for deaths with IHD as the UCOD and from 23.5% to 14.6% for deaths with IHD among the MCOD. A more pronounced decline of proportionate and case-specific mortality rate was seen in women. The decline in mortality over the whole study period was larger for acute (vs. chronic) IHD. The COVID-19 pandemic led to a marked increase in mortality in 2020 (+12.2%) with a subsequent further decline. IHD-related deaths displayed a typical seasonal pattern with more deaths during winter. The prevalence of cardiovascular risk factors was higher in IHD (vs. no IHD) deaths: this association appeared more pronounced in younger adults. CONCLUSIONS: We provided an analysis of epidemiological trends in IHD-related mortality and prevalence of risk factors. Our findings indicate a change in the pattern of cardiovascular deaths and may suggest a switch in death from acute to chronic conditions.

Diagnosis of chronic thromboembolic pulmonary hypertension after acute pulmonary embolism: data from a practice-based longitudinal cohort.

BACKGROUND: A large prospective multicenter cohort study with systematic follow-up recently reported a 2.3% 2-year cumulative incidence of chronic thromboembolic pulmonary hypertension (CTEPH) after acute pulmonary embolism (PE). OBJECTIVES: The present investigation aimed to determine the reported prevalence and incidence of CTEPH diagnosis after acute PE in real-world practice over a 12-year period. METHODS: This study was based on nationwide ambulatory billing claims and drug prescription data of all residents with public health insurance in Germany from 2010 to 2021. RESULTS: A total of 573 972 patients with acute PE (median age, 71 years; 57.4% women) were identified between 2010 and 2021. Prevalence of CTEPH among patients with history of PE increased during the period from 0.4% in 2010 to 0.9% in 2021. CTEPH was diagnosed in 2556 patients after acute PE, with most (17.6%) diagnoses reported within the first 3 months after the index PE event. The cumulative incidence rate after 3 months (first quarter) was calculated at 0.08% and after the first 2 years (eighth quarter) at 0.36%; it was 0.75% over the entire (90-month) follow-up period. Patients with CTEPH diagnosis during follow-up more often had right ventricular dysfunction at the index acute PE (14.9% vs 8.3%; P < .001). CONCLUSION: The low CTEPH incidence rate after acute PE in the present analysis suggests low awareness of CTEPH. It further suggests a lack of systematic follow-up protocols for acute PE survivors in the real world. Improved implementation of existing recommendations on follow-up strategies after PE is warranted.

The TOPOS study.

Background: We aimed to study the long-term safety and efficacy of oblique venous stents for post-thrombotic syndrome (PTS) with iliac vein compression. Patients and methods: In the multinational, prospective, single-arm TOPOS study, PTS patients scheduled for endovascular therapy with the sinus-Obliquus® stent and optional distal extension with the sinus-Venous® or sinus-XL Flex® stent were enrolled at eight European vascular centres between October 2016 and December 2020. The primary outcome was primary stent patency at 24 months, and secondary outcomes included the clinical course of PTS (Villalta score, revised Venous Clinical Severity Score [rVCSS], Visual Analog Scale [VAS] of pain), quality of life changes (Chronic Venous Insufficiency Quality of Life Questionnaire, CIVIQ-20), and device-related complications. Results: We enrolled 60 patients (mean age 46±15 years, 68% women, 13% active ulcers): 80% required stent extension (70% below the inguinal ligament). The primary patency rate at 24 months was 80.7% (95%CI 68.1-90.0%); it was higher in patients without vs. those with stent extension (90.9% vs. 78.3%, p=.01). Compared to baseline, the Villalta, rVCSS, pain VAS, and CIVIQ-20 decreased by a median of 8 (interquartile range (IQR): 4-11), 5 (IQR: 3-7), 3 (IQR: 2-5), and 17 (IQR: 6-22) points, respectively; p<.001 for all parameters. Overall, 9 events of acute stent occlusion, 4 symptomatic stent stenosis, and 1 pulmonary embolism occurred. We did not observe major bleeding events or contralateral thrombosis. Conclusions: Endovascular treatment with the oblique stent and optional stent extension was safe and resulted in high patency rates at 24 months. The reduction in PTS severity was substantial and persisted over 2-year follow-up.

Modelling Costs of Interventional Pulmonary Embolism Treatment: Implications of US Trends for a European Healthcare System.

BACKGROUND: Catheter-directed treatment (CDT) of acute pulmonary embolism (PE) is entering a growth phase in Europe following a steady increase in the United States (US) in the past decade, but the potential economic impact on European healthcare systems remains unknown. METHODS AND RESULTS: We built two statistical models for the monthly trend of proportion of CDT among patients with severe (intermediate- or high-risk) PE in the US. The conservative model was based on admission data from the National Inpatient Sample (NIS) 2016-2020, and the model reflecting increasing access to advanced treatment from the PERTTM national quality assurance database registry 2018-2021. By applying these models to the forecast of annual PE-related hospitalizations in Germany, we calculated the annual number of severe PE cases and the expected increase in CDT use for the period 2025-2030. The NIS-based model yielded a slow increase, reaching 3.1% (95% CI 3.0-3.2%) among all hospitalizations with PE in 2030; in the PERT-based model, increase would be steeper, reaching 8.7% (8.3-9.2%). Based on current reimbursement rates, we estimated an increase of annual costs for PE-related hospitalizations in Germany ranging from 15.3 to 49.8 million euros by 2030. This calculation does not account for potential cost savings, including those from reduced length of hospital stay. CONCLUSION: Our approach and results, which may be adapted to other European healthcare systems, provide a benchmark for healthcare costs expected to result from CDT. Data from ongoing trials on clinical benefits and cost savings are needed to determine cost-effectiveness and inform reimbursement decisions.

Healthcare resource utilisation and associated costs after low-risk pulmonary embolism: pre-specified analysis of the Home Treatment of Pulmonary Embolism (HoT-PE) study.

BACKGROUND: Pulmonary embolism (PE) and its sequelae impact healthcare systems globally. Low-risk PE patients can be managed with early discharge strategies leading to cost savings, but post-discharge costs are undetermined. PURPOSE: To define healthcare resource utilisation and overall costs during follow-up of low-risk PE. METHODS: We used an incidence-based, bottom-up approach and calculated direct and indirect costs over 3-month follow-up after low-risk PE, with data from the Home Treatment of Patients with Low-Risk Pulmonary Embolism (HoT-PE) cohort study. RESULTS: Average 3-month costs per patient having suffered low-risk PE were 7029.62 €; of this amount, 4872.93 € were associated with PE, accounting to 69.3% of total costs. Specifically, direct costs totalled 3019.33 €, and of those, 862.64 € (28.6%) were associated with PE. Anticoagulation (279.00 €), rehospitalisations (296.83 €), and ambulatory visits (194.95 €) comprised the majority of the 3-month direct costs. The remaining costs amounting to 4010.29 € were indirect costs due to loss of productivity. CONCLUSION: In a patient cohort with acute low-risk PE followed over 3 months, the majority of costs were indirect costs related to productivity loss, whereas direct, PE-specific post-discharge costs were low. Effective interventions are needed to reduce the burden of PE and associated costs, especially those related to productivity loss.

Functional capacity and dyspnea during follow-up after acute pulmonary embolism.

BACKGROUND: Dissecting the determinants of functional capacity during long-term follow-up after acute pulmonary embolism (PE) can help to better characterize a patient population with persisting limitation. METHODS: In a prospective cohort study, consecutive unselected survivors of acute PE underwent 3- and 12-month follow-up, including six-minute walking distance (6MWD) and dyspnea assessment with the modified Medical Research Council (mMRC) scale. We used reference equations adjusting for age, sex, and anthropometric measurements to define abnormal 6MWD. RESULTS: Overall, 323 of 363 (89.0%) patients had at least one recorded 6MWD value at one year. At 3 months, the prevalence of abnormal 6MWD was 21.9% and at 12 months it was 18.3%. At 3 and 12 months, 58.8% and 52.1% with abnormal 6MWD did not report dyspnea, respectively. On average and during follow-up, 6MWD significantly improved with time, while the mMRC dyspnea scale did not. Abnormal 6MWD was associated with younger age (odds ratio per decade, 0.91; 95% CI, 0.88-0.94), higher body mass index (1.10; 1.03-1.17), smoking (3.53; 1.34-9.31), intermediate- or high-risk PE (3.21; 1.21-8.56), and higher mMRC grading (2.28; 1.59-3.27). Abnormal 6MWD at 3 months was associated with the prospectively defined endpoint of post-PE impairment (3.72; 1.50-9.28) and with poor disease-specific and generic health-related quality of life. CONCLUSION: Three months after PE, 37% of patients reported dyspnea and 22% had abnormal 6MWD. After a year, 20% still had abnormal 6MWD. Dyspnea correlated with abnormal 6MWD, but over 50% of patients with abnormal 6MWD did not report dyspnea. Abnormal 6MWD predicted subsequent post-pulmonary embolism impairment and worse long-term quality of life. CLINICAL TRIAL REGISTRATION: German Clinical Trials Register Identifier DRKS00005939.

Prevalence and Prognostic Role of Lymphedema in Patients with Deep Venous Thrombosis and Thrombophlebitis.

Background: Deep venous thrombosis (DVT) poses a substantial disease burden. Lymphedema may present with similar symptoms making the diagnosis process more difficult. Data on the epidemiology of lymphedema are lacking. Methods: The German nationwide inpatient sample served to analyze all patients hospitalized owing to DVT and/or thrombophlebitis (referred to as DVT) of the legs in Germany between 2005 and 2020. We stratified these patients for additional lymphedema and analyzed the impact of lymphedema on adverse in-hospital events. Results: Overall, 1,136,574 hospitalizations related to DVT were recorded in Germany during 2005-2020 (53.3% women; 51.3% aged ≥70 years). Lymphedema was coded in 9974 (0.9%) patient-cases (82.0% not elsewhere classified, 17.7% secondary lymphedema). Annual numbers of hospitalizations with lymphedema among DVT patients increased from 450 (2005) to 613 (2016) (ß 0.57; 95% confidence interval [CI]: 0.48-0.66], p < 0.001) and decreased thereafter. Despite similar age, DVT patients with lymphedema had higher prevalence of cardiovascular diseases, chronic organ failure, and all types of investigated cancer. Prevalence of pulmonary embolism (PE) with shock/CPR (4.1% vs. 1.5%), acute renal failure (6.7% vs. 2.5%), and stroke (5.2% vs. 4.2%) was higher in DVT patients with lymphedema than without. Lymphedema was independently associated with PE with shock/CPR (OR: 2.1; 95% CI: 1.9-2.3) as well as death (OR: 1.3; 95% CI: 1.2-1.4). Conclusions: Comorbidity conditions like cancer, obesity, and cardiovascular risk factors, and also infectious complications, were more prevalent in DVT patients with lymphedema than in those without. Lymphedema was independently associated with severe in-hospital complications, particularly when its genesis was related to severe comorbidities.

Availability of medical and endovascular therapies for venous thromboembolism: a global survey for World Thrombosis Day.

BACKGROUND: Data on availability, affordability, and accessibility is key for the planning of global strategies to reduce the burden of venous thromboembolism (VTE). OBJECTIVES: A survey was conducted for the 10th anniversary of World Thrombosis Day to assess the availability of VTE therapies worldwide and challenges in uniform implementation. METHODS: We gathered information on the approval status, availability, utilization, occurrence of shortages, and spread of medical and interventional therapies for VTE. Furthermore, we collected information by accessing or contacting national or continental medicines agencies, manufacturers or distributors, and online drug repositories. RESULTS: We obtained data from a total of 69 countries: 33 countries in Europe, 19 in Asia, 7 in the Americas, 9 in Africa, and 1 in Oceania. Unfractionated heparin, low-molecular-weight heparin, and vitamin K antagonists were available in almost all countries, but shortages were recorded in 13%, 19%, and 15% of them, respectively. Direct oral anticoagulants were available in approximately three-quarters of the surveyed countries. At least one parenteral medication for heparin-induced thrombocytopenia was available in 57% of countries and a shortage was reported in 9% of these. Shortage of thrombolytics was recorded in 50% of countries. Overall, at least one type of catheter-directed therapy system was approved for use in 77% of countries and available in 23% of surveyed institutions. Our findings revealed notable geographic disparities in the worldwide availability of VTE therapies, the access to which appeared to be limited by economic and geopolitical factors. CONCLUSION: We anticipate that this comprehensive information will play a pivotal role in highlighting the shortcomings of VTE therapies and the lack of homogeneous availability globally.

Clinical outcomes of a balloon-expandable stent for symptomatic obstructions of the subclavian or innominate arteries.

Background: Upper-extremity peripheral arterial disease (PAD) may present with a broad spectrum of signs and symptoms. If an endovascular treatment is planned, percutaneous angioplasty and stent placement may lead to a better patency compared to percutaneous angioplasty alone. We assessed the characteristics and clinical course of patients with upper-extremity PAD who received angioplasty and a balloon-expandable stent. Patients and methods: We analyzed data from consecutive patients treated with angioplasty and placement of a balloon-expandable BeSmooth Peripheral Stent System® (Bentley, Germany) at the Angiology Department (University Hospital Zurich) between 2018 and 2022. The primary outcome was re-intervention at the target lesion within 6 months from index angioplasty and during available follow-up. The study was approved by the local ethical commission. Results: A total of 27 patients were treated. The median age was 70 (Q1-Q3: 60-74) years and 59% were men. The subclavian artery (74%) represented the most frequently treated target lesion, followed by the innominate artery (26%). The mean improvement in blood pressure in the treated arm was 21 (95%CI 7 to 35) mmHg at 24 hours and 29 (95%CI 15 to 43) mmHg at 6 months. At 6 months, 2 (8%) patients required a target lesion re-intervention. During the remaining follow-up period up to 24 months, one of these two patients required additional intervention and a total of 3 (11%) patients died due to sepsis, cancer, and unknown causes, respectively. Conclusions: Percutaneous catheter-based treatment with a balloon-expandable stent for symptomatic upper extremity PAD appeared to be effective and safe.

Coagulation-monitored, dose-adjusted catheter-directed thrombolysis or pharmaco-mechanical thrombus removal in deep vein thrombosis.

Background: Pharmaco-mechanical thrombectomy (PMT) and catheter-directed thrombolysis (CDT) are therapeutic options for selected patients with acute deep vein thrombosis (DVT) to prevent post-thrombotic syndrome (PTS). Patients and methods: We aimed to describe the clinical characteristics and outcomes of 159 patients with symptomatic iliofemoral DVT undergoing PMT alone, CDT alone, or CDT followed by PMT (bail-out) in the Swiss Venous Stent Registry. The primary outcome was the incidence of peri-interventional major and minor bleeding complications (ISTH criteria). Secondary outcomes included the incidence of PTS and stent patency after 3 years. Results: Mean age was 49±20 years and 58% were women. DVT involved the iliac veins in 99% of patients, whereas 53% had an underlying iliac vein compression. PMT alone was used in 40 patients, CDT alone in 77, and 42 received initial CDT followed by bail-out PMT due to insufficient thrombus clearance. Single-session PMT was the preferred approach in patients with iliac vein compression, patent popliteal vein, and absence of IVC thrombus. Patients treated with PMT alone received a lower r-tPA dose (median 10 mg, IQR 10-10) vs. those treated with CDT (20 mg, IQR 10-30). The rate of peri-interventional major bleeding was 0%, 1%, and 2%, whereas that of minor bleeding was 0%, 1%, and 12%, respectively, all occurring during CDT. After 3 years, PTS occurred in 6%, 9%, and 7% of patients, respectively. The primary stent patency rate was 95%, 88%, and 83%, respectively. Conclusions: The use of PMT and CDT for iliofemoral DVT was overall safe and resulted in high long-term patency and treatment success. Given the less severe presentation of DVT, single-session PMT appeared to be characterized by numerically better primary patency and lower perioperative bleeding event rates than CDT.

A nationwide analysis of reperfusion therapies for pulmonary embolism in older patients with frailty.

BACKGROUND: Reperfusion therapy is challenging in the elderly. Catheter-directed therapies are an alternative for higher-risk pulmonary embolism (PE) patients if systemic thrombolysis (ST) is contraindicated or has failed. Their safety has not been evaluated in specific vulnerable populations. AIMS: We aimed to assess the safety of reperfusion therapies in elderly and frail patients in the real world. METHODS: In the US Nationwide Inpatient Sample from 2016 to 2020, we identified hospitalisations of patients ≥65 years with PE and defined a frailty subgroup using the Johns Hopkins Adjusted Clinical Groups frailty-defining diagnosis indicator. We investigated reperfusion therapies (ST, catheter-directed thrombolysis [CDT], catheter-based thrombectomy [CBT], surgical embolectomy [SE]) and their associated safety outcomes (overall and major bleeding). RESULTS: Among 980,245 hospitalisations of patients ≥65 years with PE (28.0% frail), reperfusion therapies were used in 4.9% (17.6% among high-risk PE). ST utilisation remained stable, while the use of catheter-directed therapies increased from 1.7% in 2016 to 3.2% in 2020. Among all hospitalisations with reperfusion, CDT, compared to ST, was associated with reduced major bleeding (5.8% vs 12.2%, odds ratio [OR] 0.58, 95% confidence interval [CI]: 0.49-0.70); these results also applied to frail patients. CBT, compared to SE, was also associated with reduced major bleeding (11.0% vs 22.4%, OR 0.63, 95% CI: 0.43-0.91), but not among frail patients. These differences were particularly significant in patients with non-high-risk PE. Differences persisted for overall bleeding as well. CONCLUSIONS: Catheter-directed therapies may be a safer alternative to classical reperfusion therapies for elderly and frail patients with PE requiring reperfusion treatment.

Enoxaparin for symptomatic COVID-19 managed in the ambulatory setting: An individual patient level analysis of the OVID and ETHIC trials.

BACKGROUND: Antithrombotic treatment may improve the disease course in non-critically ill, symptomatic COVID-19 outpatients. METHODS: We performed an individual patient-level analysis of the OVID and ETHIC randomized controlled trials, which compared enoxaparin thromboprophylaxis for either 14 (OVID) or 21 days (ETHIC) vs. no thromboprophylaxis for outpatients with symptomatic COVID-19 and at least one additional risk factor. The primary efficacy outcome included all-cause hospitalization and all-cause death within 30 days from randomization. Both studies were prematurely stopped for futility. Secondary efficacy outcomes were major symptomatic venous thromboembolic events, arterial cardiovascular events, or their composite occurring within 30 days from randomization. The same outcomes were assessed over a 90-day follow-up. The primary safety outcome was major bleeding (ISTH criteria). RESULTS: A total of 691 patients were randomized: 339 to receive enoxaparin and 352 to the control group. Over 30-day follow-up, the primary efficacy outcome occurred in 6.0 % of patients in the enoxaparin group vs. 5.8 % of controls for a risk ratio (RR) of 1.05 (95%CI 0.57-1.92). The incidence of major symptomatic venous thromboembolic events and arterial cardiovascular events was 0.9 % vs. 1.8 %, respectively (RR 0.52; 95%CI 0.13-2.06). Most cardiovascular thromboembolic events were represented by symptomatic venous thromboembolic events, occurring in 0.6 % vs. 1.5 % of patients, respectively. A similar distribution of outcomes between the treatment groups was observed over 90 days. No major bleeding occurred in the enoxaparin group vs. one (0.3 %) in the control group. CONCLUSIONS: We found no evidence for the clinical benefit of early administration of enoxaparin thromboprophylaxis in outpatients with symptomatic COVID-19. These results should be interpreted taking into consideration the relatively low occurrence of events.