Atorvastatin versus placebo in patients with covid-19 in intensive care: randomized controlled trial.

OBJECTIVE: To assess the effect of statin treatment versus placebo on clinical outcomes in patients with covid-19 admitted to the intensive care unit (ICU). DESIGN: INSPIRATION/INSPIRATION-S was a multicenter, randomized controlled trial with a 2×2 factorial design. Results for the anticoagulation randomization have been reported previously. Results for the double blind randomization to atorvastatin versus placebo are reported here. SETTING: 11 hospitals in Iran. PARTICIPANTS: Adults aged ≥18 years with covid-19 admitted to the ICU. INTERVENTION: Atorvastatin 20 mg orally once daily versus placebo, to be continued for 30 days from randomization irrespective of hospital discharge status. MAIN OUTCOME MEASURES: The primary efficacy outcome was a composite of venous or arterial thrombosis, treatment with extracorporeal membrane oxygenation, or all cause mortality within 30 days from randomization. Prespecified safety outcomes included increase in liver enzyme levels more than three times the upper limit of normal and clinically diagnosed myopathy. A clinical events committee blinded to treatment assignment adjudicated the efficacy and safety outcomes. RESULTS: Of 605 patients randomized between 29 July 2020 and 4 April 2021 for statin randomization in the INSPIRATION-S trial, 343 were co-randomized to intermediate dose versus standard dose prophylactic anticoagulation with heparin based regimens, whereas 262 were randomized after completion of the anticoagulation study. 587 of the 605 participants were included in the primary analysis of INSPIRATION-S, reported here: 290 were assigned to atorvastatin and 297 to placebo (median age 57 years (interquartile range 45-68 years); 256 (44%) women). The primary outcome occurred in 95 (33%) patients assigned to atorvastatin and 108 (36%) assigned to placebo (odds ratio 0.84, 95% confidence interval 0.58 to 1.21). Death occurred in 90 (31%) patients in the atorvastatin group and 103 (35%) in the placebo group (odds ratio 0.84, 95% confidence interval 0.58 to 1.22). Rates for venous thromboembolism were 2% (n=6) in the atorvastatin group and 3% (n=9) in the placebo group (odds ratio 0.71, 95% confidence interval 0.24 to 2.06). Myopathy was not clinically diagnosed in either group. Liver enzyme levels were increased in five (2%) patients assigned to atorvastatin and six (2%) assigned to placebo (odds ratio 0.85, 95% confidence interval 0.25 to 2.81). CONCLUSIONS: In adults with covid-19 admitted to the ICU, atorvastatin was not associated with a significant reduction in the composite of venous or arterial thrombosis, treatment with extracorporeal membrane oxygenation, or all cause mortality compared with placebo. Treatment was, however, found to be safe. As the overall event rates were lower than expected, a clinically important treatment effect cannot be excluded. TRIAL REGISTRATION: ClinicalTrials.gov NCT04486508.

Thrombotic risk in patients with COVID-19.

Emerging evidences prove that the ongoing pandemic of coronavirus disease 2019 (COVID-19) is strictly linked to coagulopathy even if pneumonia appears as the major clinical manifestation. The exact incidence of thromboembolic events is largely unknown, so that a relative significant number of studies have been performed in order to explore thrombotic risk in COVID-19 patients. Cytokine storm, mediated by pro-inflammatory interleukins, tumor necrosis factor α and elevated acute phase reactants, is primarily responsible for COVID-19-associated hypercoagulopathy. Also comorbidities, promoting endothelial dysfunction, contribute to a higher thromboembolic risk. In this review we aim to investigate epidemiology and clarify the pathophysiological pathways underlying hypercoagulability in COVID-19 patients, providing indications on the prevention of thromboembolic events in COVID-19. Furthermore we aim to reassume the pathophysiological paths involved in COVID-19 infection.

Clinical Features of COVID-19 Patients With Venous Thromboembolism.

This study aimed to assess the clinical features of coronavirus disease 2019 (COVID-19) patients with VTE, to help develop preventive measures for venous thromboembolism (VTE in COVID-19) cases. COVID-19 patients admitted to Henan Provincial People's Hospital were retrospectively analyzed, including 23, 4 and 8 cases with mild to moderate, severe and critical symptoms, respectively. VTE incidence, age at onset, relevant laboratory parameters and prognosis were analyzed. Overall, VTE incidence in the 35 patients was 20.0%, occurring in severe (n = 1) and critical (n = 6) cases. D-dimer showed statistical significance in laboratory examination, representing except a diagnostic index and especial can be a prognostic factor in VTE among COVID-19 patients. Severe and critical COVID-19 cases had significantly reduced platelet counts, with a risk of hemorrhage. During treatment, the risk of both hemorrhage and thrombosis should be considered. VTE occurs in COVID-19 cases, affecting individuals with severe and critical symptoms. Significant D-dimer increase is of great significance in the risk assessment of death in critical cases of COVID-19. Appropriate measures should be taken to prevent VTE during treatment.

Incidence and Clinical Features of Venous Thromboembolism in Hospitalized Patients With Coronavirus Disease 2019 (COVID-19) in Japan.

BACKGROUND: Coronavirus disease 2019 (COVID-19) reportedly causes venous thromboembolism (VTE), but the status of this complication in Japan was unclear.Methods and Results:The VTE and COVID-19 in Japan Study is a retrospective, multicenter cohort study enrolling hospitalized patients with COVID-19 who were evaluated with contrast-enhanced computed tomography (CT) examination at 22 centers in Japan between March 2020 and October 2020. Among 1,236 patients with COVID-19, 45 (3.6%) were evaluated with contrast-enhanced CT examination. VTE events occurred in 10 patients (22.2%), and the incidence of VTE in mild, moderate, and severe COVID-19 was 0%, 11.8%, and 40.0%, respectively. COVID-19 patients with VTE showed a higher body weight (81.6 vs. 64.0 kg, P=0.005) and body mass index (26.9 vs. 23.2 kg/m2, P=0.04), and a higher proportion had a severe status for COVID-19 compared with those without. There was no significant difference in the proportion of patients alive at discharge between patients with and without VTE (80.0% vs. 88.6%, P=0.48). Among 8 pulmonary embolism (PE) patients, all were low-risk PE. CONCLUSIONS: Among a relatively small number of patients undergoing contrast-enhanced CT examination in Japanese real-world clinical practice, there were no VTE patients among those with mild COVID-19, but the incidence of VTE seemed to be relatively high among severe COVID-19 patients, although all PE events were low-risk without significant effect on mortality risk.

Incidence of thrombotic complications in COVID-19 : On behalf of ICODE: The International COVID-19 Thrombosis Biomarkers Colloquium.

A high incidence of thrombosis in hospitalised patients with COVID-19 was identified early during the pandemic. Accurately quantifying thrombotic risk may assist prognosis and guide appropriate thromboprophylaxis. Observational studies have estimated the rate of thrombosis in both hospitalised and non-hospitalised patients with COVID-19, and how this corresponds to the severity of illness. In this review, we provide an overview of the incidence and prevalence of arterial and venous thrombotic events in patients with COVID-19 and highlight the limitations in the studies to date. Asymptomatic individuals with COVID-19 and those with mild symptoms are at very low risk of thrombotic complications. However, rates of thrombosis are substantially increased in hospitalised patients, and are strikingly high in those patients who are critically-ill requiring treatment on the intensive care unit and especially those requiring extracorporeal membrane oxygenation. Clinicians managing such patients need to be aware of these risks and take appropriate steps with respect to thromboprophylaxis and heightened clinical vigilance. Large prospective observational studies will more accurately quantify thrombotic rate, and randomized controlled trials are currently investigating optimal thromboprophylactic strategies.

Screening for venous thromboembolism in patients with COVID-19.

Pulmonary thromboembolism and deep venous thrombosis occur frequently in hospitalised patients with COVID-19, the prevalence increases on the intensive care unit (ICU) and is very high in patients on extracorporeal membrane oxygenation (ECMO). We undertook a literature review to assess the usefulness of screening for peripheral venous thrombosis or pulmonary thrombosis in patients admitted with COVID-19. Outside of the ICU setting, D-dimer elevation on presentation or marked increase from baseline should alert the need for doppler ultrasound scan of the lower limbs. In the ICU setting, consideration should be given to routine screening with doppler ultrasound, given the high prevalence of thrombosis in this cohort despite standard anticoagulant thromboprophylaxis. However, absence of lower limb thrombosis on ultrasound does not exclude pulmonary venous thrombosis. Screening with CT pulmonary angiography (CTPA) is not justified in patients on the general wards, unless there are clinical features and/or marked elevations in markers of COVID-19-associated coagulopathy. However, the risk of pulmonary embolism or pulmonary thrombosis in ICU patients is very high, especially in patients on ECMO, where studies that employed routine screening for thrombosis with CT scanning have uncovered up to 100% incidence of pulmonary thrombosis despite standard anticoagulant thromboprophylaxis. Therefore, in patients at low bleeding risk and high clinical suspicion of venous thromboembolism, therapeutic anticoagulation should be considered even before screening, Our review highlights the need for increased vigilance for VTE, with a low threshold for doppler ultrasound and CTPA in high risk in-patient cohorts, where clinical features and D-dimer levels may not accurately reflect the occurrence of pulmonary thromboembolism.

D-Dimer Level and Neutrophils Count as Predictive and Prognostic Factors of Pulmonary Embolism in Severe Non-ICU COVID-19 Patients.

The incidence of pulmonary embolism (PE) is high during severe Coronavirus Disease 2019 (COVID-19). We aimed to identify predictive and prognostic factors of PE in non-ICU hospitalized COVID-19 patients. In the retrospective multicenter observational CLOTVID cohort, we enrolled patients with confirmed RT-PCR COVID-19 who were hospitalized in a medicine ward and also underwent a CT pulmonary angiography for a PE suspicion. Baseline data, laboratory biomarkers, treatments, and outcomes were collected. Predictive and prognostics factors of PE were identified by using logistic multivariate and by Cox regression models, respectively. A total of 174 patients were enrolled, among whom 86 (median [IQR] age of 66 years [55-77]) had post-admission PE suspicion, with 30/86 (34.9%) PE being confirmed. PE occurrence was independently associated with the lack of long-term anticoagulation or thromboprophylaxis (OR [95%CI], 72.3 [3.6-4384.8]) D-dimers ≥ 2000 ng/mL (26.3 [4.1-537.8]) and neutrophils ≥ 7.0 G/L (5.8 [1.4-29.5]). The presence of these two biomarkers was associated with a higher risk of PE (p = 0.0002) and death or ICU transfer (HR [95%CI], 12.9 [2.5-67.8], p < 0.01). In hospitalized non-ICU severe COVID-19 patients with clinical PE suspicion, the lack of anticoagulation, D-dimers ≥ 2000 ng/mL, neutrophils ≥ 7.0 G/L, and these two biomarkers combined might be useful predictive markers of PE and prognosis, respectively.

Cytokine storm associated coagulation complications in COVID-19 patients: Pathogenesis and Management.

INTRODUCTION: SARS-CoV-2, the causative agent of COVID-19, attacks the immune system causing an exaggerated and uncontrolled release of pro-inflammatory mediators (cytokine storm). Recent studies propose an active role of coagulation disorders in disease progression. This hypercoagulability has been displayed by marked increase in D-dimer in hospitalized patients. AREAS COVERED: This review summarizes the pathogenesis of SARS-CoV-2 infection, generation of cytokine storm, the interdependence between inflammation and coagulation, its consequences and the possible management options for coagulation complications like venous thromboembolism (VTE), microthrombosis, disseminated intravascular coagulation (DIC), and systemic and local coagulopathy. We searched PubMed, Scopus, and Google Scholar for relevant reports using COVID-19, cytokine storm, and coagulation as keywords. EXPERT OPINION: A prophylactic dose of 5000-7500 units of low molecular weight heparin (LMWH) has been recommended for hospitalized COVID-19 patients in order to prevent VTE. Treatment dose of LMWH, based on disease severity, is being contemplated for patients showing a marked rise in levels of D-dimer due to possible pulmonary thrombi. Additionally, targeting PAR-1, thrombin, coagulation factor Xa and the complement system may be potentially useful in reducing SARS-CoV-2 infection induced lung injury, microvascular thrombosis, VTE and related outcomes like DIC and multi-organ failure.

Side-Effects of COVID-19 on Patient Care: An INR Story.

BACKGROUND: Numerous studies have documented reduced access to patient care due to the COVID-19 pandemic, including access to diagnostic or screening tests, prescription medications, and treatment for an ongoing condition. In the context of clinical management for venous thromboembolism, this could result in suboptimal therapy with warfarin. We aimed to determine the impact of the pandemic on utilization of International Normalized Ratio (INR) testing and the percentage of high and low results. METHODS: INR data from 11 institutions were extracted to compare testing volume and the percentage of INR results ≥3.5 and ≤1.5 between a pre-pandemic period (January-June 2019, period 1) and a portion of the COVID-19 pandemic period (January-June 2020, period 2). The analysis was performed for inpatient and outpatient cohorts. RESULTS: Testing volumes showed relatively little change in January and February, followed by a significant decrease in March, April, and May, and then returned to baseline in June. Outpatient testing showed a larger percentage decrease in testing volume compared to inpatient testing. At 10 of the 11 study sites, we observed an increase in the percentage of abnormal high INR results as test volumes decreased, primarily among outpatients. CONCLUSION: The COVID-19 pandemic impacted INR testing among outpatients which may be attributable to several factors. Increased supratherapeutic INR results during the pandemic period when there was reduced laboratory utilization and access to care is concerning because of the risk of adverse bleeding events in this group of patients. This could be mitigated in the future by offering drive-through testing and/or widespread implementation of home INR monitoring.

The original and modified Caprini score equally predicts venous thromboembolism in COVID-19 patients.

OBJECTIVE: The study aimed to validate the original Caprini score and its modifications considering coronavirus disease (COVID-19) as a severe prothrombotic condition in patients admitted to the hospital. METHODS: The relevant data were extracted from the electronic medical records with an implemented Caprini score and were retrospectively evaluated. The score was calculated twice: by the physician on admission and by the investigator at discharge (death). The final assessment considered additional risk factors that occurred during inpatient treatment. Besides the original Caprini score (a version of 2005), the modified version added the elevation of D-dimer and specific scores for COVID-19 as follows: two points for asymptomatic, three points for symptomatic, and five points for symptomatic infection with positive D-dimer. Cases were evaluated retrospectively. The primary end point was symptomatic venous thromboembolism (VTE) detected during inpatient treatment and confirmed by appropriate imaging testing or autopsy. The secondary end points included those observed during hospitalization (admission to the intensive care unit, a requirement for invasive mechanical ventilation, death, bleeding), and those assessed at 6-month follow-up (symptomatic VTE, bleeding, death). The association of eight different versions of the Caprini score with VTE events was evaluated. RESULTS: A total of 168 patients (83 males and 85 females at the age of 58.3 ± 12.7 years) were admitted to the hospital between April 30 and May 29, 2020, and were discharged or died to the time of data analysis. The original Caprini score varied between 2 and 12 (5.4 ± 1.8) at the admission and between 2 and 15 (5.9 ± 2.5) at discharge or death. The maximal score was observed with modification including specific COVID-19 points of 5 to 20 (10.0 ± 3.0). Patients received prophylactic (enoxaparin 40 mg once daily: 2.4%), intermediate (enoxaparin 80 mg once daily: 76.8%), or therapeutic (enoxaparin 1 mg/kg twice daily: 20.8%) anticoagulation. Despite this, symptomatic VTE was detected in 11 (6.5%) inpatients. Of the 168 individuals, 28 (16.7%) admitted to the intensive care unit, 8 (4.8%) required invasive mechanical ventilation, and 8 (4.8%) died. Clinically relevant nonmajor bleeding was detected in two (1.2%) cases. The Caprini score of all eight versions demonstrated a significant association with inpatient VTE frequency. The highest predictability was observed for the original scale when assessed at discharge (death). Only symptomatic VTE was reported after discharge with a cumulative incidence of 7.1%. This did not affect the predictability of the Caprini score. Extended antithrombotic treatment was prescribed to 49 (29%) patients with a cumulative incidence of bleeding of 1.8% at 6 months. CONCLUSIONS: The study identified a significant correlation between the Caprini score and the risk of VTE in patients with COVID-19. All models including specific COVID-19 scores showed equally high predictability, and use of the original Caprini score is appropriate for patients with COVID-19.

Children and young adults hospitalized for severe COVID-19 exhibit thrombotic coagulopathy.

We report the clinical and laboratory coagulation characteristics of 27 pediatric and young adult patients (2 months to 21 years) treated for symptomatic COVID-19 at a children's hospital in the Bronx, New York, between March 1 and May 31, 2020. D-Dimer was > 0.5 µg/mL (upper limit of normal) in 25 (93%) patients at admission; 11 (41%) developed peak D-dimer > 5 µg/mL during admission. Seven (26%) patients developed venous thromboembolism: three with deep vein thrombosis and four with pulmonary embolism. Requirement of increased ventilatory support was a risk factor for thrombosis (P = 0.006). Three of eight (38%) patients on prophylactic anticoagulation developed thrombosis; however, no patients developed VTE on low-molecular-weight heparin prophylaxis titrated to anti-Xa level. Manifestation of COVID-19 disease was severe or critical in 16 (59%) patients. Four (15%) patients died of COVID-19 complications: all had comorbidities. Elevated D-dimer and increased VTE rate were observed in this young cohort, particularly in those with severe respiratory complications, suggesting thrombotic coagulopathy. More data are needed to guide thromboprophylaxis in this age group.

The Impact of COVID-19 on Vascular Surgery Practice: A Systematic Review.

BACKGROUND: COVID-19 is characterized by a pulmonary interstitial compromise which can require intensive care unit (ICU) and mechanical ventilation. Covid patients develop a wide range of pathologies. This study aims to identify the impact of COVID-19 in diseases commonly treated by vascular surgeons. METHODS: Four conditions were selected: venous thromboembolism (VTE), pulmonary embolism (PE), peripheral arterial disease (PAD), and microangiopathy. A systematic review of the literature using PRISMA guidelines was. RESULTS: Out of 1195 papers reviewed for conditions in COVID-19 patients relevant to routine vascular surgery practice, 43 papers were included and analyzed. Venous thrombosis was found to be the most common COVID-19 associated pathology with a cumulative incidence of 25% at 7 days and 48% at 14 days. Additionally, D-dimer levels proved to be a good predictor, even in the early stages of the disease with a sensitivity of 85%, specificity of 88.5% and a negative predictive value of 94.7%. Patients in the ICU demonstrated a significantly higher risk of developing VTE, even when receiving pharmacologic thromboprophylaxis. Although evidence of arterial thrombosis was less common (1% to 16.3%), its consequences were typically more serious, including limb loss and death even in young individuals (OR = 25, 95% CI). Finally, microangiopathy has a wide spectrum of clinical presentations from retinal microangiopathy to other more severe manifestations such as myocardial injury, pulmonary compromise and potential multiple organ dysfunction syndrome. CONCLUSIONS: Although the pathophysiological pathway by which COVID-19 produces thrombosis is not completely clear, the incidence of both arterial and venous thrombosis is increased. D-dimer screening should be done in all COVID-19 patients, as a predictor of thrombotic complications.

Disease Severity and Perinatal Outcomes of Pregnant Patients With Coronavirus Disease 2019 (COVID-19).

OBJECTIVE: To describe coronavirus disease 2019 (COVID-19) severity in pregnant patients and evaluate the association between disease severity and perinatal outcomes. METHODS: We conducted an observational cohort study of all pregnant patients with a singleton gestation and a positive test result for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) who delivered at 1 of 33 U.S. hospitals in 14 states from March 1 to July 31, 2020. Disease severity was classified by National Institutes of Health criteria. Maternal, fetal, and neonatal outcomes were abstracted by centrally trained and certified perinatal research staff. We evaluated trends in maternal characteristics and outcomes across COVID-19 severity classes and associations between severity and outcomes by multivariable modeling. RESULTS: A total of 1,219 patients were included: 47% asymptomatic, 27% mild, 14% moderate, 8% severe, 4% critical. Overall, 53% were Hispanic; there was no trend in race-ethnicity distribution by disease severity. Those with more severe illness had older mean age, higher median body mass index, and pre-existing medical comorbidities. Four maternal deaths (0.3%) were attributed to COVID-19. Frequency of perinatal death or a positive neonatal SARS-CoV-2 test result did not differ by severity. Adverse perinatal outcomes were more frequent among patients with more severe illness, including 6% (95% CI 2-11%) incidence of venous thromboembolism among those with severe-critical illness compared with 0.2% in mild-moderate and 0% in asymptomatic (P<.001 for trend across severity). In adjusted analyses, severe-critical COVID-19 was associated with increased risk of cesarean birth (59.6% vs 34.0%, adjusted relative risk [aRR] 1.57, 95% CI 1.30-1.90), hypertensive disorders of pregnancy (40.4% vs 18.8%, aRR 1.61, 95% CI 1.18-2.20), and preterm birth (41.8% vs 11.9%, aRR 3.53, 95% CI 2.42-5.14) compared with asymptomatic patients. Mild-moderate COVID-19 was not associated with adverse perinatal outcomes compared with asymptomatic patients. CONCLUSION: Compared with pregnant patients with SARS-CoV-2 infection without symptoms, those with severe-critical COVID-19, but not those with mild-moderate COVID-19, were at increased risk of perinatal complications.

Thrombosis, Bleeding, and the Observational Effect of Early Therapeutic Anticoagulation on Survival in Critically Ill Patients With COVID-19.

BACKGROUND: Hypercoagulability may be a key mechanism of death in patients with coronavirus disease 2019 (COVID-19). OBJECTIVE: To evaluate the incidence of venous thromboembolism (VTE) and major bleeding in critically ill patients with COVID-19 and examine the observational effect of early therapeutic anticoagulation on survival. DESIGN: In a multicenter cohort study of 3239 critically ill adults with COVID-19, the incidence of VTE and major bleeding within 14 days after intensive care unit (ICU) admission was evaluated. A target trial emulation in which patients were categorized according to receipt or no receipt of therapeutic anticoagulation in the first 2 days of ICU admission was done to examine the observational effect of early therapeutic anticoagulation on survival. A Cox model with inverse probability weighting to adjust for confounding was used. SETTING: 67 hospitals in the United States. PARTICIPANTS: Adults with COVID-19 admitted to a participating ICU. MEASUREMENTS: Time to death, censored at hospital discharge, or date of last follow-up. RESULTS: Among the 3239 patients included, the median age was 61 years (interquartile range, 53 to 71 years), and 2088 (64.5%) were men. A total of 204 patients (6.3%) developed VTE, and 90 patients (2.8%) developed a major bleeding event. Independent predictors of VTE were male sex and higher D-dimer level on ICU admission. Among the 2809 patients included in the target trial emulation, 384 (11.9%) received early therapeutic anticoagulation. In the primary analysis, during a median follow-up of 27 days, patients who received early therapeutic anticoagulation had a similar risk for death as those who did not (hazard ratio, 1.12 [95% CI, 0.92 to 1.35]). LIMITATION: Observational design. CONCLUSION: Among critically ill adults with COVID-19, early therapeutic anticoagulation did not affect survival in the target trial emulation. PRIMARY FUNDING SOURCE: None.

An Evidence-based Protocol for Minimizing Thromboembolic Events in SARS-CoV-2 Infection.

Coronavirus Disease 2019 (COVID-19) is complicated by significant coagulopathy, that manifests in the form of both pulmonary artery microthromboses and systemic venous thromboembolism (VTE) leading to excess mortality. Dysregulated innate immune response in the lung due to viral-entry mediated angiotensin-I-converting enzyme 2 (ACE2) receptor downregulation causes endothelial injury in the pulmonary vasculature, inflammatory cytokine release, increased thrombin generation and impaired fibrinolysis. The inflammatory disease process, immobilization with prolonged hospital stay, hypoxia due to extensive lung injury and pre-existing comorbidities can contribute to thromboembolic episodes (TE). The observed risk for TE in COVID-19 is high despite anticoagulation, particularly in intensive care unit (ICU) patients. A high level of clinical suspicion, lower threshold for diagnostic imaging and aggressive early and extended thromboprophylaxis is indicated. The available evidence on the optimal strategies to prevent, diagnose, and treat VTE in patients with COVID-19 is heterogenous, but rapidly evolving. We propose an evidence-based, risk-stratified protocol in approaching the risk of TE episodes in COVID-19 patients.

Pharmacologic Thromboprophylaxis and Thrombosis in Hospitalized Patients with COVID-19: A Pooled Analysis.

BACKGROUND: Coronavirus disease 2019 (COVID-19) increases thrombosis in hospitalized patients prompting adoption of different thromboprophylaxis strategies. Safety and efficacy of escalated-dose pharmacologic thromboprophylaxis are not established. OBJECTIVES: To determine the pooled incidence of thrombosis/bleeding in hospitalized patients with COVID-19 for standard-dose, intermediate-dose, therapeutic anticoagulation, and no pharmacologic thromboprophylaxis. METHODS: MEDLINE, EMBASE, and Cochrane CENTRAL were searched up to August 29, 2020 for studies reporting pharmacologic thromboprophylaxis and thrombosis or bleeding. Pooled event rates were calculated using a random-effects model. RESULTS: Thirty-five observational studies were included. The pooled incidence rates of total venous thromboembolism (N = 4,685) were: no prophylaxis 41.9% (95% confidence interval [CI]: 28.1-57.2, I 2 = 76%), standard-dose prophylaxis 19.8% (95% CI: 13.2-28.6, I 2 = 95%), intermediate-dose prophylaxis 11.9% (95% CI: 4.3-28.6, I 2 = 91%), and therapeutic-dose anticoagulants 10.5% (95% CI: 4.2-23.8, I 2 = 82%, p = 0.003). The pooled incidence rates of arterial thrombosis (N = 1,464) were: no prophylaxis 11.3% (95% CI: 5.2-23.0, I 2 = 0%), standard-dose prophylaxis 2.5% (95% CI: 1.4-4.3, I 2 = 45%), intermediate-dose prophylaxis 2.1% (95% CI: 0.5-7.7, I 2 = 45%), and therapeutic-dose anticoagulants 1.3% (95% CI: 0.2-8.8, I 2 = 0, p = 0.009). The pooled bleeding event rates (N = 6,393) were nonsignificantly higher in therapeutic-dose anticoagulants compared with standard-dose prophylaxis, (6.3 vs. 1.7%, p = 0.083). CONCLUSION: Thrombosis rates were lower in hospitalized COVID-19 patients who received pharmacologic thromboprophylaxis. Thrombosis and bleeding rates for patients receiving intermediate-dose thromboprophylaxis or therapeutic anticoagulation were similar to those who received standard-dose pharmacologic thromboprophylaxis.