The Pitfalls of Global Hemostasis Assays in Myeloproliferative Neoplasms and Future Challenges.

Venous and arterial thromboembolism are major complications of myeloproliferative neoplasms (MPNs), comprising polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). Global hemostasis assays, including thrombin generation assay (TGA), rotational thromboelastometry (ROTEM), and thromboelastography (TEG), have been proposed as biomarkers to assess the hypercoagulability and thrombotic risk stratification in MPNs. We performed a systematic literature review on the parameters of TGA, ROTEM, and TEG and their association with thrombotic events and treatment strategies in MPNs. Thirty-two studies (all cross-sectional) were included, which collectively enrolled 1,062 controls and 1,608 MPN patients. Among the 13 studies that reported arterial or venous thrombosis, the overall thrombosis rate was 13.8% with 6 splanchnic thromboses reported. Out of the 27 TGA studies, there was substantial heterogeneity in plasma preparation and trigger reagents employed in laboratory assays. There was a trend toward increased peak height among all MPN cohorts versus controls and higher endogenous thrombin potential (ETP) between ET patients versus controls. There was an overall trend toward lower ETP between PV and PMF patients versus. controls. There were no substantial differences in ETP between JAK2-positive versus JAK2-negative MPNs, prior history versus negative history of thrombotic events, and among different treatment strategies. Of the three ROTEM studies, there was a trend toward higher maximum clot firmness and shorter clot formation times for all MPNs versus controls. The three TEG studies had mixed results. We conclude that the ability of parameters from global hemostasis assays to predict for hypercoagulability events in MPN patients is inconsistent and inconclusive. Further prospective longitudinal studies are needed to validate these biomarker tools so that thrombotic potential could be utilized as a primary endpoint of such studies.

Artificial intelligence in the prediction of venous thromboembolism: A systematic review and pooled analysis.

BACKGROUND: Accurate diagnostic and prognostic predictions of venous thromboembolism (VTE) are crucial for VTE management. Artificial intelligence (AI) enables autonomous identification of the most predictive patterns from large complex data. Although evidence regarding its performance in VTE prediction is emerging, a comprehensive analysis of performance is lacking. AIMS: To systematically review the performance of AI in the diagnosis and prediction of VTE and compare it to clinical risk assessment models (RAMs) or logistic regression models. METHODS: A systematic literature search was performed using PubMed, MEDLINE, EMBASE, and Web of Science from inception to April 20, 2021. Search terms included "artificial intelligence" and "venous thromboembolism." Eligible criteria were original studies evaluating AI in the prediction of VTE in adults and reporting one of the following outcomes: sensitivity, specificity, positive predictive value, negative predictive value, or area under receiver operating curve (AUC). Risks of bias were assessed using the PROBAST tool. Unpaired t-test was performed to compare the mean AUC from AI versus conventional methods (RAMs or logistic regression models). RESULTS: A total of 20 studies were included. Number of participants ranged from 31 to 111 888. The AI-based models included artificial neural network (six studies), support vector machines (four studies), Bayesian methods (one study), super learner ensemble (one study), genetic programming (one study), unspecified machine learning models (two studies), and multiple machine learning models (five studies). Twelve studies (60%) had both training and testing cohorts. Among 14 studies (70%) where AUCs were reported, the mean AUC for AI versus conventional methods were 0.79 (95% CI: 0.74-0.85) versus 0.61 (95% CI: 0.54-0.68), respectively (p < .001). However, the good to excellent discriminative performance of AI methods is unlikely to be replicated when used in clinical practice, because most studies had high risk of bias due to missing data handling and outcome determination. CONCLUSION: The use of AI appears to improve the accuracy of diagnostic and prognostic prediction of VTE over conventional risk models; however, there was a high risk of bias observed across studies. Future studies should focus on transparent reporting, external validation, and clinical application of these models.

Survival outcomes with warfarin compared with direct oral anticoagulants in cancer-associated venous thromboembolism in the United States: A population-based cohort study.

BACKGROUND: Direct oral anticoagulants (DOACs) have comparable efficacy with low-molecular-weight heparin (LMWH) for the treatment of cancer-associated venous thromboembolism (VTE). Whether there is a mortality benefit of DOACs compared with warfarin in the management of VTE in cancer is not established. METHODS AND FINDINGS: Utilizing the United States' Surveillance, Epidemiology, and End Results (SEER)-Medicare linked databases from 2012 through 2016, we analyzed overall survival in individuals diagnosed with a primary gastric, colorectal, pancreas, lung, ovarian, or brain cancer and VTE who received a prescription of DOAC or warfarin within 30 days of VTE diagnosis. Patients were matched 1:2 (DOAC to warfarin) through exact matching for cancer stage and propensity score matching for age, cancer site, cancer stage, and time interval from cancer to VTE diagnosis. The analysis identified 4,274 patients who received a DOAC or warfarin for the treatment of VTE within 30 days of cancer diagnosis (1,348 in DOAC group and 2,926 in warfarin group). Patients were of median age 75 years and 56% female. Within the DOAC group, 1,188 (88%) received rivaroxaban, and 160 (12%) received apixaban. With a median follow-up of 41 months, warfarin was associated with a statistically significantly higher overall survival compared to DOACs (median overall survival 12.0 months [95% confidence interval (CI): 10.9 to 13.5] versus 9.9 months [95% CI: 8.4 to 11.2]; hazard ratio (HR) 0.85; 95% CI: 0.78 to 0.91; p < 0.001). Observed differences in survival were consistent across subgroups of cancer sites, cancer stages, and type of VTE. The study limitations include retrospective design with potential for unaccounted confounders along with issues of generalizability beyond the cancer diagnoses studied. CONCLUSIONS: In this analysis of a population-based registry, warfarin was associated with prolonged overall survival compared to DOACs for treatment of cancer-associated VTE.

Thromboembolic and hemorrhagic risks after vaccination against SARS-CoV-2: a systematic review and meta-analysis of randomized controlled trials.

BACKGROUND: Thromboembolic and bleeding events after vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are major public concerns leading to vaccine hesitancy. Due to low incidence, an individual randomized controlled trial (RCT) is underpowered to determine whether SARS-CoV-2 vaccines increase the risks of thromboembolism and hemorrhage. METHODS: We performed a literature search using PubMed, EMBASE, Cochrane, medRxiv databases, and reference lists of relevant articles to identify RCTs that reported thromboembolic, hemorrhagic events, and thromboembolism/hemorrhage-related death after SARS-CoV-2 vaccination. The primary aim of this systematic review and meta-analysis was to estimate the pooled thromboembolic risk related to SARS-CoV-2 vaccines compared to placebo. The secondary outcomes included estimating the risks of arterial thromboembolism (ATE), venous thromboembolisms (VTE), hemorrhage, thrombocytopenia, and thromboembolism/hemorrhage-related death. RESULTS: Eight RCTs of 4 vaccine platforms comprised of 195,196 participants were retrieved. SARS-CoV-2 vaccines were not associated with an increased risk of overall thromboembolism (risk ratio [RR], 1.14; 95% CI [confidence interval], 0.61-2.14; I2 = 35%), ATE (RR, 0.97; 95% CI, 0.46-2.06; I2 = 21%), VTE (RR, 1.47; 95% CI, 0.72-2.99; I2 = 0%), hemorrhage (RR, 0.97; 95% CI, 0.35-2.68; I2 = 0), and thromboembolism/hemorrhage-related death (RR, 0.53; 95% CI, 0.16-1.79; I2 = 0). Compared to the baseline estimated risk of these outcomes in participants administered placebos, the risk differences with vaccines were very small and not statistically significant. These findings were consistent in the subgroup analysis across 4 vaccine platforms. CONCLUSION: Vaccines against SARS-CoV-2 are not associated with an increased risk of thromboembolism, hemorrhage, and thromboembolism/hemorrhage-related death.

Iron deficiency anemia interfering the diagnosis of compound heterozygosity for Hb constant spring and Hb Paksé: The first case report.

BACKGROUND: Diagnosis of thalassemia or hemoglobinopathy concomitant with iron deficiency anemia (IDA) is challenging. METHOD: We report a case of 43-year-old female whose diagnosis of compound heterozygosity for hemoglobin Constant Spring (HbCS) and Hb Paksé became apparent after the treatment of IDA. RESULTS: Prior to treatment, Hb analysis using isoelectric focusing (IEF) showed HbA 95.6%, HbA2 2.7%, and HbCS 1.7% compatible with heterozygous HbCS. After 4 months of oral iron therapy resulting in an improved Hb level, her HbCS level was substantially increased to 8.7% on IEF suggesting homozygous HbCS. Subsequent DNA analysis using multiplex amplification refractory mutation system analysis revealed compound heterozygosity for HbCS and Hb Paksé. CONCLUSION: This case demonstrated that IDA can significantly reduce HbCS/Hb Paksé levels and probably mask the diagnosis of homozygous HbCS, homozygous Hb Paksé or the compound heterozygosity for both hemoglobinopathies by hemoblogin analysis. The test should be repeated after resolution of IDA, or molecular testing should be performed to confirm the diagnosis.

A meta-analysis to assess the risk of bleeding and thrombosis following chimeric antigen receptor T-cell therapy: Communication from the ISTH SSC Subcommittee on Hemostasis and Malignancy.

BACKGROUND: Chimeric antigen receptor T-cell (CAR T-cell) therapy is increasingly utilized for treatment of hematologic malignancies. Hematologic toxicities including thrombosis and bleeding complications have been reported. Accurate estimates for thrombotic and bleeding outcomes are lacking. OBJECTIVES: We performed a systematic review and meta-analysis in patients who received CAR T-cell therapy for an underlying hematologic malignancy with the objective to: a) assess the thrombosis and bleeding risk associated with CAR T-cell therapy, b) assess the impact of CRS and ICANS on the risks of thrombosis and bleeding, and c) assess the safety of anticoagulant or antiplatelet use in the period following treatment with CAR T-cell therapy. METHODS: We searched MEDLINE, EMBASE, and Cochrane CENTRAL up to February 2022 for studies reporting thrombotic or bleeding outcomes in patients receiving CAR T-cell therapy. Pooled event rates were calculated using a random-effects model. We performed subgroup analyses stratified by follow-up duration, CAR T-cell target antigen, and underlying hematologic malignancy. RESULTS: We included 47 studies with a total of 7040 patients. High heterogeneity between studies precluded reporting of overall pooled rates of thrombotic and bleeding events. In studies with follow-up duration of ≤6 months, the pooled incidence of venous thrombotic events was 2.4% (95% CI, 1.4%-3.4%; I2 = 0%) per patient-month, whereas the rate was 0.1% (95% CI, 0%-0.1%; I2 = 0%) per patient-month for studies with longer follow-up periods (>6 months). The pooled incidences of any bleeding events per patient-month in studies with follow-up duration of ≤6 months and >6 months were 1.9% (95% CI, 0.6%-3.1%; I2 = 78%) and 0.3% (95% CI: 0%-0.8%, I2 = 40%), respectively. Secondary analyses by CAR T-cell target antigen, underlying malignancy, and primary outcome of the studies did not reveal significant differences in the rates of thromboembolism, any bleeding events, or major bleeding events. CONCLUSION: The risk of both thrombosis and bleeding following CAR T-cell therapy appears to be highest in the initial months following infusion.

Comparison of direct oral anticoagulants versus low-molecular-weight heparin in primary and metastatic brain cancers: a meta-analysis and systematic review.

BACKGROUND: The safety and efficacy of direct-acting oral anticoagulants (DOACs) for therapeutic anticoagulation in the setting of primary or metastatic brain cancer is not known. OBJECTIVES: To conduct a meta-analysis and systematic review of studies that compare the risk of intracranial hemorrhage (ICH) in patients with brain cancer treated with DOACs vs low-molecular-weight heparin (LMWH). METHODS: A literature search was conducted using PubMed, EMBASE, and Cochrane databases. Summary statistics were obtained by calculating the risk ratio (RR), and heterogeneity across studies was estimated using the I2 statistic. A total of 10 retrospective studies (n = 1638) met criteria for inclusion. The primary endpoint was the pooled RR for ICH in patients with brain tumors receiving anticoagulation with DOACs compared with those receiving LMWH. Secondary analyses included the risk of fatal ICH in each subgroup. RESULTS: The pooled RR for ICH in patients receiving DOACs vs those receiving LMWH was 0.65 (95% CI, 0.36-1.17; P = .15; I2 = 50%). In studies evaluating primary brain cancer, there was a reduction in risk of ICH with DOACs (RR, 0.35; 95% CI, 0.18-0.69; P = .003; I2 = 0%). In patients with metastatic brain cancer, there was no difference in the risk of ICH with the type of anticoagulation (RR, 1.05; 95% CI, 0.71-1.56; P = .80; I2 = 0%). The overall risk of fatal ICH was not different between anticoagulants. CONCLUSION: The risk of ICH in patients with brain cancer receiving therapeutic anticoagulation varies by anticoagulation agent and diagnosis of primary or metastatic disease.

Machine learning natural language processing for identifying venous thromboembolism: systematic review and meta-analysis.

ABSTRACT: Venous thromboembolism (VTE) is a leading cause of preventable in-hospital mortality. Monitoring VTE cases is limited by the challenges of manual medical record review and diagnosis code interpretation. Natural language processing (NLP) can automate the process. Rule-based NLP methods are effective but time consuming. Machine learning (ML)-NLP methods present a promising solution. We conducted a systematic review and meta-analysis of studies published before May 2023 that use ML-NLP to identify VTE diagnoses in the electronic health records. Four reviewers screened all manuscripts, excluding studies that only used a rule-based method. A meta-analysis evaluated the pooled performance of each study's best performing model that evaluated for pulmonary embolism and/or deep vein thrombosis. Pooled sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) with confidence interval (CI) were calculated by DerSimonian and Laird method using a random-effects model. Study quality was assessed using an adapted TRIPOD (Transparent Reporting of a multivariable prediction model for Individual Prognosis Or Diagnosis) tool. Thirteen studies were included in the systematic review and 8 had data available for meta-analysis. Pooled sensitivity was 0.931 (95% CI, 0.881-0.962), specificity 0.984 (95% CI, 0.967-0.992), PPV 0.910 (95% CI, 0.865-0.941) and NPV 0.985 (95% CI, 0.977-0.990). All studies met at least 13 of the 21 NLP-modified TRIPOD items, demonstrating fair quality. The highest performing models used vectorization rather than bag-of-words and deep-learning techniques such as convolutional neural networks. There was significant heterogeneity in the studies, and only 4 validated their model on an external data set. Further standardization of ML studies can help progress this novel technology toward real-world implementation.

Four-factor prothrombin complex concentrate for the treatment of oral factor Xa inhibitor-associated bleeding: a meta-analysis of fixed versus variable dosing.

Background: The optimal dosing strategy of four-factor prothrombin complex concentrate (4F-PCC) to treat oral factor Xa (FXa) inhibitor-associated bleeding has not been established. Objectives: To evaluate the effectiveness and safety of fixed versus variable 4F-PCC dosing for the management of FXa inhibitor-associated bleeding. Methods: A systematic literature search and meta-analysis of clinical studies was performed using PubMed, Embase, and Cochrane databases from inception to January 2022. The primary outcomes included hemostatic effectiveness, mortality, and thromboembolic events. Secondary outcomes included 4F-PCC usage, total length of stay in hospital and in intensive care units, and time to 4F-PCC administration. The pooled incidence or mean was calculated using a random-effects model and compared between the 2 dosing strategies. Results: Twenty-five studies were included and data from 1,760 patients (fixed dosing, n = 228; variable dosing, n = 1,532) were analyzed. There were no significant differences in hemostatic effectiveness, thromboembolic events, or mortality rates between the dosing strategies. Hospital length of stay was significantly longer in the fixed-dosing group, with a mean stay of 7.4 days (95% CI: 3.6-11.1) compared to 5.9 days (95% CI: 5.5-6.3) in the variable-dosing group (P < 0.001). The mean initial 4F-PCC dose was significantly higher with variable dosing than fixed dosing (38 IU/kg; 95% CI: 32-44 vs. 27 IU/kg; 95% CI: 26-28, P < 0.001). Conclusions: A fixed-dosing strategy appears to be a safe and effective alternative to variable weight-based dosing and was associated with lower 4F-PCC usage. However, direct comparative studies are needed to confirm these results.

The dos, don'ts, and nuances of thrombophilia testing.

Considerable progress has been made in elucidating genetic and biologic risk factors for venous thromboembolism (VTE). Despite being able to identify heritable defects in a substantial proportion of patients with VTE, testing has not, in general, proven useful in management. Despite efforts to reduce inappropriate testing, it often falls to the hematologist to consult on patients having undergone thrombophilia testing. Through a series of cases, we discuss how D-dimer testing can be helpful in VTE recurrence risk stratification in younger women as well as how to approach patients with persistently elevated D-dimer levels in the absence of thrombosis. While elevated factor VIII coagulant activity levels are a significant risk factor for a first episode of VTE, its biologic basis is not fully understood, and studies have not shown it to be a useful predictor of recurrence. Abnormal results of genetic tests for methylene tetrahydrofolate reductase or plasminogen activator 1 promoter polymorphisms may be encountered, which carry little if any thrombotic risk and should never be ordered. We also discuss protein S deficiency, the most difficult of the hereditary thrombophilias to diagnose due to a wider "normal" range in the general population as compared with protein C, the presence of both free and bound forms in plasma, and the characteristics of the various assays in use. We also present a rare type of protein C deficiency that can be missed by functional assays using an amidolytic rather than a clotting end point.

Laboratory Monitoring of Heparin Anticoagulation in Hemodialysis: Rationale and Strategies.

Unfractionated heparin (UFH) and low-molecular-weight heparins (LMWHs) are commonly used to prevent clotting of the hemodialysis extracorporeal circuit and optimize hemodialysis adequacy. There is no consensus on the optimal dosing for UFH and LMWHs during hemodialysis. In clinical practice, semiquantitative clotting scoring of the dialyzer and venous chamber may help to guide UFH and LMWH dose adjustment. Laboratory monitoring has not been shown to improve clinical outcomes and is therefore not routinely indicated in most hemodialysis patients. It might, however, be considered in select patients, such as those with extremes of body weight or history of repeated clotting or bleeding. Methods for laboratory monitoring include the activated partial thromboplastin time, activated clotting time, and antifactor Xa assays for UFH and antifactor Xa assay for LMWHs. Target ranges for anticoagulation in hemodialysis have been suggested but not clearly defined. When utilizing these tests, issues such as availability, standardization, interfering factors, and interpretation must be considered. In this narrative review, we discuss the rationale and methods of monitoring anticoagulation in hemodialysis.

Recommendation on the nomenclature for anticoagulants: updated communication from the International Society on Thrombosis and Haemostasis Scientific and Standardization Commitee on the Control of Anticoagulation.

Oral anticoagulation therapy has evolved beyond vitamin K antagonists to include oral direct thrombin inhibitors and factor Xa inhibitors. Collectively known as "direct oral anticoagulants," this class of medications represents the current standard of care for the prevention and treatment of common thrombotic disorders, including atrial fibrillation and venous thromboembolism. Medications that target factors XI/XIa and XII/XIIa are currently under investigation for several thrombotic and nonthrombotic conditions. Given that these emerging medications will likely have distinct risk-benefit profiles to the current direct oral anticoagulants, may have different routes of administration, and could be used for unique clinical conditions (e.g., hereditary angioedema), the International Society on Thrombosis and Haemostasis Subcommittee on Control of Anticoagulation assembled a writing group to make recommendations on the nomenclature of anticoagulant medications. With input from the broader thrombosis community, the writing group recommends that anticoagulant medications be described by the route of administration and specific targets (e.g., oral factor XIa inhibitor).

The impact of warfarin on overall survival in cancer patients.

Venous thromboembolism (VTE) is a common complication in patients with cancer. Warfarin has largely been replaced by low-molecular-weight heparin (LMWHs) and direct oral anticoagulants (DOACs) as the standard of care in cancer-associated VTE. The survival benefit of these anticoagulants over warfarin in the cancer population was not demonstrated in clinical trials, possibly due to insufficient sample size and limited follow-up duration. There are emerging population-based studies suggesting that warfarin may be associated with improved overall survival in cancers and may have a protective effect against certain types of cancers. Warfarin may exert its anti-neoplastic properties through both coagulation pathway -dependent and -independent mechanisms, the latter of which are mediated by inhibition of the Gas6-AXL signaling pathway. Further research should emphasize on identifying clinical and laboratory predictors of beneficial effects of warfarin. In this review article, we summarize and update the current evidence regarding the potential impact of warfarin on the overall survival of cancer patients and incidence of cancer, as well as review the potential mechanism of such effect and future perspectives.

Immunogenicity and risks associated with impaired immune responses following SARS-CoV-2 vaccination and booster in hematologic malignancy patients: an updated meta-analysis.

Patients with hematologic malignancies (HM) have demonstrated impaired immune responses following SARS-CoV-2 vaccination. Factors associated with poor immunogenicity remain largely undetermined. A literature search was conducted using PubMed, EMBASE, Cochrane, and medRxiv databases to identify studies that reported humoral or cellular immune responses (CIR) following complete SARS-CoV-2 vaccination. The primary aim was to estimate the seroconversion rate (SR) following complete SARS-CoV-2 vaccination across various subtypes of HM diseases and treatments. The secondary aims were to determine the rates of development of neutralizing antibodies (NAb) and CIR following complete vaccination and SR following booster doses. A total of 170 studies were included for qualitative and quantitative analysis of primary and secondary outcomes. A meta-analysis of 150 studies including 20,922 HM patients revealed a pooled SR following SARS-CoV-2 vaccination of 67.7% (95% confidence interval [CI], 64.8-70.4%; I2 = 94%). Meta-regression analysis showed that patients with lymphoid malignancies, but not myeloid malignancies, had lower seroconversion rates than those with solid cancers (R2 = 0.52, P < 0.0001). Patients receiving chimeric antigen receptor T-cells (CART), B-cell targeted therapies or JAK inhibitors were associated with poor seroconversion (R2 = 0.39, P < 0.0001). The pooled NAb and CIR rates were 52.8% (95% CI; 45.8-59.7%, I2 = 87%) and 66.6% (95% CI, 57.1-74.9%; I2 = 86%), respectively. Approximately 20.9% (95% CI, 11.4-35.1%, I2 = 90%) of HM patients failed to elicit humoral and cellular immunity. Among non-seroconverted patients after primary vaccination, only 40.5% (95% CI, 33.0-48.4%; I2 = 87%) mounted seroconversion after the booster. In conclusion, HM patients, especially those with lymphoid malignancies and/or receiving CART, B-cell targeted therapies, or JAK inhibitors, showed poor SR after SARS-CoV-2 vaccination. A minority of patients attained seroconversion after booster vaccination. Strategies to improve immune response in these severely immunosuppressed patients are needed.

Systemic Coagulopathy in Hospitalized Patients With Coronavirus Disease 2019: A Systematic Review and Meta-Analysis.

Coagulation activation has been reported in several cohorts of patients Coronavirus Disease 2019 (COVID-19). However, the true burden of systemic coagulopathy in COVID-19 remains unknown. In this systematic review and meta-analysis, we performed a literature search using PubMed, EMBASE, and Cochrane Database to identify studies that reported the prevalence of systemic coagulopathy using established criteria in patients with COVID-19. The primary outcome was the prevalence of systemic coagulopathy (disseminated intravascular coagulation [DIC] and/or sepsis-induced coagulopathy [SIC]). Pooled prevalences and 95% confidence intervals [CIs] were calculated using random-effects model. A total of 5 studies including 1210 patients with confirmed COVID-19 were included. The pooled prevalence of systemic coagulopathy was 7.1% (95%CI: 3.2%,15.3%, I2 = 93%). The pooled prevalence of DIC (N = 721) and SIC (N = 639) were 4.3% (95%CI 1.7%, 10.4%, I2 = 84%) and 16.2% (95%CI: 9.3%, 26.8%, I2 = 74%), respectively. Only 2 studies reported the prevalence of elevated D-dimer levels with the pooled prevalence of 84.6% (95%CI: 52.0%,96.5%, I2 = 94%). Average D-dimer and fibrinogen levels were remarkably increased, while platelet counts, PT, and aPTT ratios were minimally affected in COVID-19. The estimated prevalence of systemic coagulopathy in patients with COVID-19 was low despite D-dimer elevation in most patients. Relatively low systemic coagulopathy in COVID-19 may contribute to the high incidence of thrombosis rather than bleeding in patients with COVID-19.

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.

Anticoagulation and In-Hospital Mortality From Coronavirus Disease 2019: A Systematic Review and Meta-Analysis.

Hypercoagulability in coronavirus disease 2019 (COVID-19) may aggravate disease severity during hospitalization but the reported survival benefits from anticoagulation (AC) vary among studies. We performed a literature research to estimate pooled odds ratios (ORs) of in-hospital mortality and major bleeding comparing among intermediate-to-therapeutic dose AC, prophylactic dose AC, and no AC. Until October 22, 2020, PubMed, EMBASE, and Cochrane Library Database were searched for studies reporting AC utilization and mortality in COVID-19. Studies with suspected risk of bias were excluded before the synthesis of pooled ORs with 95% confidence intervals (CIs) using random-effects models. Of 37 identified studies (N = 19,510), 17 (N = 17,833) were aggregated in the meta-analysis. The overall mortality rate was 23.1% (95% CI 18.7-28.2). The pooled odds of mortality comparing anticoagulated to non-anticoagulated patients were similar, but lower in prophylactic dose AC group (OR 0.83; 95% CI 0.73-0.95). Notably, intermediate-to-therapeutic dose AC increased mortality (OR 1.60; 95% CI 1.11-2.31) and major bleeding compared to prophylactic dose AC (OR 3.33; 95% CI 2.34-4.72). Our findings support the optimal efficacy and safety profiles of prophylactic dose AC in hospitalized COVID-19 patients.

Discordant reporting of VTE in pancreatic cancer: A systematic review and meta-analysis of thromboprophylaxis versus chemotherapeutic trials.

BACKGROUND: Despite the frequency of venous thromboembolism (VTE) in pancreatic cancer, it is inconsistently reported as an adverse event in clinical trials. We hypothesized that reported rates of VTE in pancreatic cancer clinical trials are influenced by the objectives of the trial, with higher rates reported in thromboprophylaxis compared with chemotherapeutic trials. We performed a systematic review and meta-analysis of randomized, controlled trials (RCT) in pancreatic cancer to quantify differences in reported rates of VTE in thromboprophylaxis and chemotherapeutic trials. METHODS: We systematically searched MEDLINE, EMBASE, and Clinicaltrials.gov. Eligible thromboprophylaxis RCTs were required to report rates of thrombosis in non-anticoagulant pancreatic cancer cohorts. Eligible chemotherapy studies were RCTs evaluating chemotherapy regimens in advanced pancreatic cancer and reported thrombosis as adverse events. Pooled event rates of VTE and arterial thrombosis were calculated using a random-effects model. RESULTS: The pooled VTE rate in 13 chemotherapy studies (5694 patients) was 5.9% (95% confidence interval [CI], 3.9-9.0%) compared with 16.5% (95% CI, 11.7%-23.3%; P < .001) in 9 thromboprophylaxis studies (631 patients). The pooled symptomatic VTE rate from chemotherapy studies was 5.4% (95% CI, 3.5%-8.3%), which was significantly lower than the pooled rate from thromboprophylaxis studies of 10.5% (95% CI, 7.3%-14.9%; P = .02). CONCLUSION: The VTE incidence reported in chemotherapy RCTs in pancreatic cancer is significantly lower than reported in thromboprophylaxis studies. This finding highlights the underrecognition of VTE in chemotherapeutic trials and emphasizes the need to standardize approaches towards monitoring and reporting of VTE in clinical trials.

Extended thromboprophylaxis for medically ill patients with cancer: a systemic review and meta-analysis.

Hospitalized medically ill patients with cancer are at increased risk of both venous thromboembolism and bleeding. The safety and efficacy of extended thromboprophylaxis in patients with cancer are unclear. We conducted a systematic review and meta-analysis of the literature using of MEDLINE, EMBASE, and the Cochrane CENTRAL databases to identify cancer subgroups enrolled in randomized controlled trials evaluating extended thromboprophylaxis following hospitalization. The primary outcomes were symptomatic and incidental venous thromboembolic events and hemorrhage (major hemorrhage and clinically relevant nonmajor bleeding). Four randomized controlled trials reported the outcomes of extended thromboprophylaxis in 3655 medically ill patients with active or history of cancer. The rates of venous thromboembolic events were similar between the extended-duration and standard-duration groups (odds ratio [OR], 0.85; 95% confidence interval [CI], 0.61-1.18; I2 = 0%). However, major and clinically relevant nonmajor bleeding occurred significantly more frequently in the extended-duration thromboprophylaxis group (OR, 2.10; 95% CI, 1.33-3.35; I2 = 8%). Extended thromboprophylaxis in hospitalized medically ill patients with cancer was not associated with a reduced rate of venous thromboembolic events but was associated with increased risk of hemorrhage. This study protocol was registered on PROSPERO as #CRD42020209333.