Patients with COVID-19 develop an increased risk of thromboembolism. Thromboprophylaxis is recommended for hospitalized COVID-19 patients, but the role of thromboprophylaxis in outpatients with COVID-19 is less well defined. We conducted a systematic review and meta-analysis to evaluate the safety and efficacy of thromboprophylaxis among outpatients with COVID-19. We searched PubMed, Embase, Cochrane Central Register of Controlled Trials, Web of Science, and Scopus from inception to August 2023. The outcomes of interest were venous thromboembolic events including deep venous thrombosis and pulmonary embolism, all-cause mortality, cardiovascular events, hospitalization, major bleeding events, and non-major bleeding events. We included 6 trials comprising 3352 patients. Patients who received thromboprophylaxis had an approximately 70% reduction in venous thromboembolism (RR, 0.28 [95% CI, 0.08 to 0.93]) compared to patients who did not receive thromboprophylaxis. The risk of mortality (RR, 0.79 [95% CI, 0.35 to 1.77]), cardiovascular events (RR, 0.91 [95% CI, 0.30 to 2.73]), and hospitalization (RR, 1.09 [95% CI, 0.81 to 1.47]) were similar between the two groups. Patients who received thromboprophylaxis had a higher risk of non-major bleeding (RR, 3.48 [95% CI, 1.72 to 7.05) compared to patients who did not receive thromboprophylaxis. Thromboprophylaxis reduced the risk of venous thromboembolism but not mortality, cardiovascular events, or hospitalization among outpatients with COVID-19.

Venous thromboembolism (VTE) poses a significant challenge in the context of multiple myeloma, with an incidence of up to 10% in newly diagnosed patients and varying frequency in the relapsed/refractory setting. Accurate VTE risk assessment and personalized thromboprophylaxis strategies are important parts of supportive care in myeloma. There are three validated risk assessment models for prediction of VTE risk in newly diagnosed myeloma-SAVED, IMPEDE-VTE, and PRISM. In this review, we delve into the practical applications of VTE risk prediction models in the context of current therapies. By emphasizing the necessity of a tailored approach, we underscore the importance of considering patient-specific, disease-specific, and treatment-specific risk factors in each clinical scenario, and using that data to complement the output from risk assessment models. We also provide a summary of currently available data on VTE thromboprophylaxis in myeloma, and highlight specific situations where direct oral anticoagulants should be strongly considered. Our objective is to fill the critical gaps in VTE prophylaxis and management through the analysis of specific patient cases and provide a practical overview for clinicians.

Asparaginase is essential in the initial management of acute lymphoblastic leukemia (ALL) but frequently leads to venous thromboembolism (VTE). Using anticoagulants for primary VTE prevention has been studied with no consensus. We conducted a systematic literature search in PubMed, Scopus, and Web of science and performed random-effect meta-analysis using Mantel-Haenszel method in RevMan 5.4 to analyze primary pharmacological thromboprophylaxis during asparaginase treatment in early-phase (induction, consolidation, or intensification phase) therapy in patients with ALL with all ages and followed with subgroup analysis by age. Meta-analysis of 13 articles describing the effect of antithrombin supplementation in 1375 patients showed that antithrombin prophylaxis decreases the risk of VTE by 43% (RR, 0.57; 95% CI, 0.38 - 0.83; p=0.004), with mild heterogeneity (I2=35%, p=0.10) and moderate certainty by GRADE. 8 articles included for meta-analysis of low-molecular weight heparin (LMWH) treatment in 612 patients showed that it decreased the risk of VTE by nearly 40% (RR, 0.61; 95% CI, 0.45 - 0.81; p=0.00081), with minimal heterogeneity (I2=14%, p=0.31) but low certainty. Subgroup analysis showed that only prophylaxis with antithrombin supplementation significantly decreased the VTE rate in adult patients with moderate certainty. In pediatric patients, one nonrandomized prospective study showed that LMWH combined with antithrombin has a better thromboprophylaxis effect than antithrombin alone. In the PREVAPIX-ALL trial, prophylaxis with direct factor Xa inhibitor Apixaban did not benefit children younger than 18 years except for cases of obesity. We concluded that thromboprophylaxis with antithrombin is effective in ALL patients older than 18 years during the early phase of therapy, and LMWH combined with antithrombin supplementation might be effective for pediatric patients with ALL. Apixaban is effective in pediatric ALL patients with obesity and needs further study in other high-risk patients.

Cancer is a known risk factor for venous thromboembolism (VTE). The wider adoption of immunotherapy and anti-angiogenic drugs in recent years have increased this risk further. Central venous catheters (CVCs) are widely used access devices utilized to deliver infusion therapy, mostly in ambulatory settings. The endothelial injury associated with the use of these catheters adds to the risk of VTE to already high-risk patients. The introduction of direct oral anticoagulants (DOACs), with its proven efficacy and safety in multiple clinical indications, have renewed the attention to VTE prophylaxis in cancer patients with CVC. Several clinical trials and meta-analyses had shown that both apixaban and rivaroxaban are effective in lowering the risk of VTE, without increasing the risk of bleeding. Several risk assessment models (RAM) have utilized patient-related, tumor-related, and treatment-related factors, in addition to widely available biomarkers, like Hemoglobin (Hb) level, white blood cell (WBC) and platelets counts to stratify patients into two or three VTE risk levels. In this manuscript, we review the published clinical trials and meta-analyses that attempted to study the efficacy and safety of anticoagulants, mostly the DOACs, in cancer patients with CVCs. We will also propose a practical risk-directed approach to enhance VTE prophylaxis rate.

UNASSIGNED: Pharmacological prophylaxis to prevent venous thromboembolism is currently recommended for women assessed as being at high risk of venous thromboembolism during pregnancy or in the 6 weeks after delivery (the puerperium). The decision to provide thromboprophylaxis involves weighing the benefits, harms and costs, which vary according to the individual\'s venous thromboembolism risk. It is unclear whether the United Kingdom\'s current risk stratification approach could be improved by further research.
UNASSIGNED: To quantify the current decision uncertainty associated with selecting women who are pregnant or in the puerperium for thromboprophylaxis and to estimate the value of one or more potential future studies that would reduce that uncertainty, while being feasible and acceptable to patients and clinicians.
UNASSIGNED: A decision-analytic model was developed which was informed by a systematic review of risk assessment models to predict venous thromboembolism in women who are pregnant or in the puerperium. Expected value of perfect information analysis was used to determine which factors are associated with high decision uncertainty and should be the target of future research. To find out whether future studies would be acceptable and feasible, we held workshops with women who have experienced a blood clot or have been offered blood-thinning drugs and surveyed healthcare professionals. Expected value of sample information analysis was used to estimate the value of potential future research studies.
UNASSIGNED: The systematic review included 17 studies, comprising 19 unique externally validated risk assessment models and 1 internally validated model. Estimates of sensitivity and specificity were highly variable ranging from 0% to 100% and 5% to 100%, respectively. Most studies had unclear or high risk of bias and applicability concerns. The decision analysis found that there is substantial decision uncertainty regarding the use of risk assessment models to select high-risk women for antepartum prophylaxis and obese postpartum women for postpartum prophylaxis. The main source of decision uncertainty was uncertainty around the effectiveness of thromboprophylaxis for preventing venous thromboembolism in women who are pregnant or in the puerperium. We found that a randomised controlled trial of thromboprophylaxis in obese postpartum women is likely to have substantial value and is more likely to be acceptable and feasible than a trial recruiting women who have had a previous venous thromboembolism. In unselected postpartum women and women following caesarean section, the poor performance of risk assessment models meant that offering prophylaxis based on these models had less favourable cost effectiveness with lower decision uncertainty.
UNASSIGNED: The performance of the risk assessment model for obese postpartum women has not been externally validated.
UNASSIGNED: Future research should focus on estimating the efficacy of pharmacological thromboprophylaxis in pregnancy and the puerperium, and clinical trials would be more acceptable in women who have not had a previous venous thromboembolism.
UNASSIGNED: This study is registered as PROSPERO CRD42020221094.
UNASSIGNED: This award was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme (NIHR award ref: NIHR131021) and is published in full in Health Technology Assessment; Vol. 28, No. 9. See the NIHR Funding and Awards website for further award information.
Women who are pregnant or who have given birth in the previous 6 weeks are at increased risk of developing blood clots that can cause serious illness or death. Small doses of blood thinners given by injection are safe in pregnancy and can reduce the risk of blood clots, but they can slightly increase the risk of bleeding. Healthcare professionals use risk assessment tools to decide if a woman is at high risk of blood clots and should be offered blood thinners. We wanted to find out what research would be useful to help them make better decisions. We reviewed previous research to establish which risk assessment tools are best at predicting who will have a blood clot. We then created a mathematical model to predict what would happen when using different risk assessment tools to decide who should be offered blood thinners, both during pregnancy and after giving birth. We found that there was a lot of uncertainty about which women should be offered blood thinners. This was mainly because there have only been a few small studies comparing blood thinners to no treatment in pregnant women or women who have recently given birth. We estimated the value of future studies comparing blood thinners to no treatment, in groups of women with different risk factors, by predicting what information we would gain and how this would be used to improve decisions about using blood thinners. To find out whether these studies would be acceptable and feasible, we held workshops with women who have experienced a blood clot or have been offered blood thinners and surveyed healthcare professionals. We found that a study in obese women who have recently given birth would have substantial value and may be more acceptable than a study in pregnant women with a previous blood clot.

BACKGROUND: Direct oral anticoagulants (DOACs) used as an alternative to low-molecular-weight heparin (LMWH) for thromboprophylaxis after cancer surgery for venous thromboembolic events (VTE) remains unclear. This study aimed to investigate the efficacy and safety of DOACs versus LMWH in these patients.
METHODS: A search of EMBASE, MEDLINE, Cochrane Central Register of Controlled Trials (CENTRAL), and Web of Science was carried out and included all randomized controlled trials (RCTs) and observational studies that directly compared DOACs with LMWH for thromboprophylaxis in patients after cancer surgery through July 25, 2023. The primary efficacy and safety outcomes were VTE, major bleeding, and clinically relevant non-major bleeding (CRNMB) within 30 days of surgery. The risk of bias was assessed using the Cochrane Risk of Bias 2 (RoB2) tool for RCTs and ROBINS-I tool for non-randomized studies. This study was registered in PROSPERO (CRD42023445386).
RESULTS: We retrieved 5149articles, selected 27 for eligibility, and included 10 studies (three RCTs and seven observational studies) encompassing 3054 patients who underwent postoperative thromboprophylaxis with DOACs (41%) or LMWH (59%). Compared to LMWH thromboprophylaxis, DOACs had a comparable risk of VTE (RR:0.69[95% CI:0.46-1.02], I2 = 0%), major bleeding (RR:1.55 [95% CI:0.82-2.93], I2 = 2%), and CRNMB (RR, 0.89 [95% CI, 0.4-1.98], I2 = 31%) during the 30-day postoperative period. Subgroup analysis of VTE and major bleeding suggested no differences according to study type, extended thromboprophylaxis, tumor types, or different types of DOAC.
CONCLUSIONS: DOACs are potentially effective alternatives to LMWH for thromboprophylaxis in patients undergoing cancer surgery, without increasing the risk of major bleeding events.

BACKGROUND: Venous thromboembolism (VTE) is a well-recognized complication after total joint replacement (TJR). Persons with hemophilia A or B are considered at low postoperative VTE risk due to their coagulation factor deficiencies, and administering pharmacologic thromboprophylaxis is often considered contraindicated. However, using factor replacement therapy could increase the postoperative VTE risk.
OBJECTIVE: To analyze best available evidences of VTE rates in persons with hemophilia A or B undergoing lower limb TJR and the use of postoperative pharmacologic thromboprophylaxis.
METHODS: We systematically screened 4 online biomedical databases to identify studies reporting VTE rates in patients with hemophilia after TJR. Case reports and case series with less than 10 patients were excluded.
RESULTS: Twenty-six observational studies were included in this systematic review, reporting 1181 TJRs in patients with hemophilia A or B. Eight studies had VTE rates as the primary outcome. Five studies reported screen-detected VTE, while 21 reported symptomatic VTE events. Overall, 17 VTE events were reported (1.4%; 95% CI, 0.9%-2.3%), including 10 (6.6%) after 151 surgeries with postoperative VTE screening and 7 (0.7%) after 1080 surgeries without postoperative screening. Thromboprophylaxis protocols were specified in 21 studies; postoperative thromboprophylaxis was used in 15 (1.3%) surgeries. This information was not available for 29.0% of the analyzed population.
CONCLUSIONS: Despite the low thromboprophylaxis use in patients with hemophilia, rates of symptomatic VTE after TJR appeared to be low. We also highlighted the need to better report the thrombotic outcome in persons with hemophilia to face the ongoing changes in the hemophilia landscape.

UNASSIGNED: Venous thromboembolism (VTE), including deep vein thrombosis (DVT) and pulmonary embolism (PE), is a potentially devastating complication after surgery. Spine surgery is associated with an increased risk of postoperative bleeding, such as spinal epidural hematomas (SEH), which complicates the use of anticoagulation. Despite this dilemma, there is a lack of consensus around perioperative VTE prophylaxis. This systematic review investigates the relationship between chemoprophylaxis and the incidence rates of VTE and SEH in the elective spine surgical population.
UNASSIGNED: A comprehensive literature search was performed using PubMed, Embase, and Cochrane databases to identify studies published after 2,000 that compared VTE chemoprophylaxis use in elective spine surgery. Studies involving patients aged < 18 years or with known trauma, cancer, or spinal cord injuries were excluded. Pooled incidence rates of VTE and SEH were calculated for all eligible studies, and meta-analyses were performed to assess the relationship between chemoprophylaxis and the incidences of VTE and SEH.
UNASSIGNED: Nineteen studies met our eligibility criteria, comprising a total of 220,932 patients. The overall pooled incidence of VTE was 3.2%, including 3.3% for DVT and 0.4% for PE. A comparison of VTE incidence between patients that did and did not receive chemoprophylaxis was not statistically significant (OR 0.97, p=.95, 95% CI 0.43-2.19). The overall pooled incidence of SEH was 0.4%, and there was also no significant difference between patients that did and did not receive chemoprophylaxis (OR 1.57, p=.06, 95% CI 0.99-2.50).
UNASSIGNED: The use of perioperative chemoprophylaxis may not significantly alter rates of VTE or SEH in the elective spine surgery population. This review highlights the need for additional randomized controlled trials to better define the risks and benefits of specific chemoprophylactic protocols in various subpopulations of elective spine surgery.

This comprehensive review introduces the critical issue of venous thromboembolism (VTE), emphasizing its prevalence, particularly in developed countries, and its role as a leading cause of preventable deaths. It discusses the components of VTE, encompassing deep vein thrombosis (DVT) and pulmonary embolism (PE), with a focus on the clinical challenges of diagnosing silent VTE in hospitalized patients. The review underscores the shocking statistics associated with VTE, including its impact on patient mortality, especially in medically treated, acutely ill patients. Despite the availability of evidence-based guidelines recommending VTE prophylaxis, there is a significant gap in implementation, making it a leading cause of unexpected hospital deaths. Additionally, the review outlines the multifaceted nature of VTE risk factors, ranging from transient to persistent and provoked to unprovoked, providing a comprehensive understanding of patient-specific considerations. The latter part of the review delves into the impact of VTE on patient health outcomes, revealing its adverse effects on survival, recurrence rates, and psychosocial well-being. Furthermore, it explores various preventive measures, including pharmacological and mechanical options, and their effectiveness, highlighting the importance of a multimodal approach. The review also touches on the challenges of guideline adherence and patient-centered considerations in VTE prevention.

OBJECTIVE: This study aimed to provide procedure-specific estimates of the risk for symptomatic venous thromboembolism and major bleeding in noncancer gynecologic surgeries.
METHODS: We conducted comprehensive searches on Embase, MEDLINE, Web of Science, and Google Scholar. Furthermore, we performed separate searches for randomized trials that addressed the effects of thromboprophylaxis.
METHODS: Eligible studies were observational studies that enrolled ≥50 adult patients who underwent noncancer gynecologic surgery procedures and that reported the absolute incidence of at least 1 of the following: symptomatic pulmonary embolism, symptomatic deep vein thrombosis, symptomatic venous thromboembolism, bleeding that required reintervention (including re-exploration and angioembolization), bleeding that led to transfusion, or postoperative hemoglobin level <70 g/L.
METHODS: A teams of 2 reviewers independently assessed eligibility, performed data extraction, and evaluated the risk of bias of the eligible articles. We adjusted the reported estimates for thromboprophylaxis and length of follow-up and used the median value from studies to determine the cumulative incidence at 4 weeks postsurgery stratified by patient venous thromboembolism risk factors and used the Grading of Recommendations Assessment, Development and Evaluation approach to rate the evidence certainty.
RESULTS: We included 131 studies (1,741,519 patients) that reported venous thromboembolism risk estimates for 50 gynecologic noncancer procedures and bleeding requiring reintervention estimates for 35 procedures. The evidence certainty was generally moderate or low for venous thromboembolism and low or very low for bleeding requiring reintervention. The risk for symptomatic venous thromboembolism varied from a median of <0.1% for several procedures (eg, transvaginal oocyte retrieval) to 1.5% for others (eg, minimally invasive sacrocolpopexy with hysterectomy, 1.2%-4.6% across patient venous thromboembolism risk groups). Venous thromboembolism risk was <0.5% for 30 (60%) of the procedures; 0.5% to 1.0% for 10 (20%) procedures; and >1.0% for 10 (20%) procedures. The risk for bleeding the require reintervention varied from <0.1% (transvaginal oocyte retrieval) to 4.0% (open myomectomy). The bleeding requiring reintervention risk was <0.5% in 17 (49%) procedures, 0.5% to 1.0% for 12 (34%) procedures, and >1.0% in 6 (17%) procedures.
CONCLUSIONS: The risk for venous thromboembolism in gynecologic noncancer surgery varied between procedures and patients. Venous thromboembolism risks exceeded the bleeding risks only among selected patients and procedures. Although most of the evidence is of low certainty, the results nevertheless provide a compelling rationale for restricting pharmacologic thromboprophylaxis to a minority of patients who undergo gynecologic noncancer procedures.