Systematic review of randomized controlled trials of new anticoagulants for venous thromboembolism prophylaxis in major orthopedic surgeries, compared with enoxaparin

Is there a role for the laboratory monitoring in the management of specific antidotes of direct oral anticoagulants?

Given the growing number of patients receiving direct oral anticoagulant (DOAC), patients requiring rapid neutralization is also increasing in case of major bleedings or urgent surgery/procedures. Idarucizumab is commercialized as a specific antidote to dabigatran while andexanet alfa has gained the Food and Drug Administration and the European Medicines Agency approval as an oral anti-factor Xa inhibitors antidote. Other antidotes or hemostatic agents are still under preclinical or clinical development, the most advanced being ciraparantag. DOAC plasma levels measurement allows to appropriately select patient for antidote administration and may prevent unnecessary prescription of expensive molecules in some acute clinical settings. However, these tests might be inconclusive after some antidote administration, namely andexanet alfa and ciraparantag. The benefit of laboratory monitoring following DOAC reversal remains unclear. Here, we sought to provide an overview of the key studies evaluating the safety and efficacy of DOAC reversal using the most developed/commercialized specific antidotes, to discuss the potential role of the laboratory monitoring in the management of patients receiving DOAC specific antidotes and to highlight the areas that deserve further investigations in order to establish the exact role of laboratory monitoring in the appropriate management of DOAC specific antidotes.

Incidence of venous thromboembolism in pediatric orthopedics: A systematic review

BACKGROUNDS

Children undergoing orthopedic procedures often present numerous risk factors for thromboembolism. A recent survey, conducted by the Pediatric Orthopaedic Society of North America (POSNA), indicates that pediatric orthopedic surgeons are unaware of venous thromboembolism (VTE) prevention protocols and feel that certain procedures should require thromboprophylaxis. The aim of this systematic review was to properly assess the incidence of VTE in pediatric orthopedics. By using a thorough and broad search of the literature, the incidence according to different subspecialties of pediatric orthopedics was evaluated.

METHODS

A systematic review on VTE in pediatric orthopedics was conducted. Four databases were searched for articles reporting these events. Three major search concepts: "pediatrics", "orthopedic surgery/trauma" and "VTE complications" were used and broken down in MeSH, EmTree and their free vocabulary synonyms for proper literature review. Two independent authors screened 8467 titles and abstracts. Seventy articles reporting VTE in children treated by orthopedic surgeons were selected for data extraction. We reported median incidences by orthopedic subtypes and by study characteristics with a semi-quantitative review model.

RESULTS

The 70 articles yielded a total of 845,010 participants. Spine articles (33/70) provided 25,2% of the children included in the review. Trauma studies (16/70) accounted for 47.5% of the participants. The overall VTE median incidence was 0.16% [95% CI: 0.0-1.01%]. Musculoskeletal infections had a noticeably higher median incidence of 3.5% [CI: 0.0-13.8%]. Small variations were seen for the other subtypes: trauma, spine and elective surgeries. Subgroups by article characteristics did not differ significantly either.

CONCLUSION

Thrombotic complications are rare events in pediatric orthopedics, but knowledge epidemiologic is important because its potential severity. In this review, VTE median incidence for all orthopedic subtypes was around 0.16% [CI: 0.0-1.01%]. According to subspecialty assessment, musculoskeletal infections were associated with greater risk of VTE occurrence.

LEVEL OF EVIDENCE

III - Systematic review.

Association Between Venous Thromboembolism Prophylaxis and the Incidence of Thromboembolism Following Orthopedic Procedures: A Cross-Sectional Study

INTRODUCTION

Venous thromboembolism (VTE) is a significant concern following orthopedic procedures, necessitating effective prophylactic measures. The rates of VTE prophylaxis, however, vary widely between institutions and nations, falling between 13% and 70% on average. In the absence of adequate thromboprophylaxis, pulmonary embolism, which accounts for 5% to 10% of mortality in hospitalized patients, is one of the leading causes of death. This study investigates the relationship between VTE prophylaxis and thromboembolism incidence, considering patient characteristics, risk assessment completion, anticoagulant prescription, and weight-bearing status.

OBJECTIVES

To evaluate the knowledge gap by examining the relationship between VTE prevention and the prevalence of thromboembolism also to examine the anticoagulant prescription trends for patients being discharged from orthopedic operations and to investigate the connection between post-procedure weight-bearing status and the development of VTE problems.

METHODOLOGY

A retrospective, cross-sectional design was employed, analyzing 200 orthopedic procedure patients from January to June of 2023 performed at Rehman Medical Institute. After getting ethical approval from the institutional ethical approval board, data were collected on the basis of variables encompassing patient attributes, surgery details, VTE risk factors, prophylaxis type, and VTE complications. Data was entered and analyzed via IBM SPSS Statistics for Windows, Version 22 (Released 2013; IBM Corp., Armonk, New York, United States), and the data were run through various tests including descriptive statistics, cross-tabulations, and chi-square. Results were then presented in the form of a table.

RESULTS

Among 200 individuals 24 individuals experienced VTE, while 176 did not. Significant gender-based VTE differences were observed (p = 0.01). Hypertension (HTN) showed a significant association (p = 0.04) with VTE. Major surgeries were correlated with higher VTE incidence (p = 0.03). Pharmacological prophylaxis reduced the occurrence of VTE (p = 0.01). Early mobilization and Ted stockings were correlated with lower VTE incidence (p = 0.04, p = 0.12).

CONCLUSION

This study reveals gender-specific VTE differences, emphasizes the role of HTN, surgical nature, and prophylaxis in VTE incidence, and supports tailored prophylactic strategies. Our findings align with previous research and emphasize the significance of tailored prophylaxis strategies. By examining multiple factors, including gender, co-morbidities, surgical characteristics, and prophylactic methods, our study contributes to the evidence base that supports clinical decision-making and enhances patient safety in orthopedic surgery.

A Prospective Randomized Controlled Trial Comparing Enoxaparin & Rivaroxaban for Venous Thromboembolism Prophylaxis in Orthopaedic Trauma

OBJECTIVES

To determine whether there is a difference in orthopaedic trauma patient medication satisfaction and adherence using an oral versus subcutaneous injectable anticoagulant for venous thromboembolism chemoprophylaxis.

DESIGN

Randomized controlled trial.

SETTING

Single academic Level 1 trauma center.

PARTICIPANTS

One hundred twenty adult orthopaedic trauma patients with operative pelvic or lower extremity fractures were randomized and completed the study.

INTERVENTION

Three weeks of either the service standard 40 mg once daily enoxaparin versus trial medication 10 mg once daily rivaroxaban postoperatively.

MAIN OUTCOME MEASURES

Patient satisfaction as measured by the Treatment Satisfaction Questionnaire for Medication (TSQM-9). Medication adherence as measured by the Morisky Medication Adherence Scale (MMAS-8).

RESULTS

Medication adherence was similar in both groups. Medication satisfaction was significantly higher in the oral rivaroxaban group based on the TSQM-9 and patient-reported data. Secondary outcomes found no significant difference in the incidence of bleeding events or clinically relevant venous thromboembolism. The enoxaparin group experienced more adverse medication-related events. The rivaroxaban medication regimen costs 7.5-10× less out of pocket for uninsured patients.

CONCLUSION

The results of this randomized controlled trial demonstrate that patients with surgical orthopaedic trauma prefer an oral anticoagulant for postoperative venous thromboembolism chemoprophylaxis and suggest that rivaroxaban may be a viable option. Furthermore, large-scale studies are needed to confirm safety and efficacy for rivaroxaban in this population as a potential alternative to enoxaparin and aspirin.

LEVEL OF EVIDENCE

Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

Risk of nonmajor bleeding upon use of direct oral anticoagulants for preventing and treating venous thromboembolism: A network meta-analysis

INTRODUCTION

Direct oral anticoagulants (DOACs) are associated with bleeding. Patients often stop taking DOACs due to nonmajor bleeding, which may lead to venous thromboembolism (VTE) recurrence. We aimed to determine the risk of nonmajor bleeding using different DOACs to prevent and treat VTE.

METHODS

PubMed, Embase, Web of Science, and Cochrane Library databases were searched from inception until January 6, 2021. The incidence of clinically relevant nonmajor bleeding and minor bleeding was investigated. In frequentist-based network meta-analysis, we analyzed the odds ratio (OR) with 95% CI and the surface under the cumulative ranking curves (SUCRA).

RESULTS

Twenty-seven randomized controlled trials (RCTs) (involving 64,493 patients) were included. For preventing VTE, the risk for clinically relevant nonmajor bleeding was lowest for apixaban, followed by that for low-molecular weight heparin (LMWH), dabigatran, edoxaban, and rivaroxaban. The risk for minor bleeding was lowest for apixaban, followed by that for rivaroxaban, LMWH, dabigatran, and edoxaban. For treating VTE, the risk for clinically relevant nonmajor bleeding was also lowest for apixaban, followed by that for edoxaban, vitamin K antagonists (VKAs), and rivaroxaban. The risk for minor bleeding was lowest for apixaban, followed by that for rivaroxaban and VKAs.

CONCLUSIONS

Regardless of whether it was used for preventing or treating VTE, apixaban had the lowest risk of nonmajor bleeding. This suggests that apixaban may have a lower risk of nonmajor bleeding than other anticoagulants and may help provide some clinical reference for choosing a more appropriate drug for the patient.

Optimizing pharmacologic thromboprophylaxis use in pediatric orthopedic surgical patients through implementation of a perioperative venous thromboembolism risk screening tool

BACKGROUND

Although rare, venous thromboembolic events (VTE) are a significant challenge in pediatric orthopedic surgical patients (POSP). A VTE thromboprophylaxis screening tool was developed and implemented in POSPs at the IWK Health Centre since October 2016.

OBJECTIVES

This retrospective cohort study was designed to evaluate and assess the impact of the VTE thromboprophylaxis screening tool in terms of use of thromboprophylaxis in POSP.

METHODS

Using the tool, POSPs were screened and were categorized into risk groups. Patient groups were compared and spearman correlation analysis was performed to show the strength of association between risk factors and thromboprophylaxis. Retrospective screening of pre-algorithm patients who received thromboprophylaxis was done to further assess the screening tool.

RESULTS

After the implementation of the VTE thromboprophylaxis screening tool in POSPs, there was a 47.9% reduction in the use of thromboprophylaxis (P = 0.046) as compared with before. Neither VTE nor significant bleeding complications occurred before or after screening tool implementation. Compliance with the screening tool was excellent (100% of patients in the high-risk category received thromboprophylaxis). High-risk patients were more likely to have body mass index  > 30 (35.7%), limited/altered mobility (57.1%), and to be undergoing a complicated/repeat surgery (64.3%).

CONCLUSIONS

The present study demonstrates successful implementation of a VTE thromboprophylaxis screening tool that resulted in significant reduction in use of thromboprophylaxis in POSPs with no increase in VTE or change in bleeding complications.

Clinical characteristics of acute lower extremity deep venous thrombosis diagnosed by duplex in patients hospitalized for coronavirus disease 2019

OBJECTIVE

Little is known about coronavirus disease 2019 (COVID-19)-associated hypercoagulability. We sought to characterize patients with deep venous thrombosis (DVT) identified after admission for COVID-19.

METHODS

All adult patients admitted to Montefiore Medical Center from March 1, 2020, to April 10, 2020, and undergoing lower extremity venous duplex for DVT evaluation were included. Patients admitted with suspicion of COVID-19 were divided into severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) positive and SARS-CoV-2 negative groups based on in-hospital test results. Patients without clinical suspicion for COVID-19 were not tested. A retrospective case-control study design was used to identify potential risk factors for DVT in patients with COVID-19. Demographic, radiographic, and laboratory values were abstracted and analyzed.

RESULTS

During the study period, 3404 patients with confirmed COVID-19 were admitted to the hospital. Of the 135 SARS-CoV-2 patients who underwent duplex scanning, there were 18 (13.3%) noted to have DVT compared with 72 of the 711 patients (10.1%) who were either SARS-CoV-2 negative or untested. The odds ratio for DVT in COVID-19 was 1.35 (95% confidence interval, 0.78-2.34; P = .289). Baseline characteristics for COVID-19 patients with and without DVT were overall similar. COVID-19 patients with DVT had an elevated median first d-dimer (18.88 μg/mL [interquartile range (IQR), 7.79-20.00] vs 2.55 μg/mL [IQR, 1.45-6.28]; P = .002; reference value, <0.5 μg/mL), average in-hospital d-dimer (median, 11.93 μg/mL [IQR, 8.25-16.97] vs 3.54 μg/mL [IQR, 2.05-8.53]; P < .001) and median fibrinogen level (501.0 [IQR, 440.0-629.0] vs 654.5 [IQR, 535.8-780.0]; P = .002; reference range, 187-502 mg/dL). There was a trend to significance for COVID-19 patients with DVT compared with without DVT in median d-dimer levels at the time of the duplex (13.61 μg/mL [IQR, 4.04-19.97] vs 3.58 μg/mL [IQR, 2.51-9.62]; P = .055) and median ferritin levels (1679.0 ng/mL [IQR, 1168.0-2577.0] vs 1103.0 ng/mL [IQR, 703.5-2076.5]; P = .055; reference range, 25-270 ng/mL). Twelve of the 18 patients with COVID who developed DVT did so despite chemical thromboprophylaxis, and 2 developed DVT despite therapeutic anticoagulation CONCLUSIONS: We found only a modestly increased risk of DVT in patients with COVID-19, likely underestimated owing to limitations in duplex testing early in the epidemic. Elevated d-dimer and a less elevated fibrinogen are associated with DVT in patients with COVID-19 who seem to form thrombus despite conventional chemical thromboprophylaxis. Additionally, an increasing d-dimer over time may be a reflection of the development of DVT in patients with COVID-19.

Anticoagulation in COVID-19: Effect of Enoxaparin, Heparin, and Apixaban on Mortality

Background  Mortality in coronavirus disease of 2019 (COVID-19) is associated with increases in prothrombotic parameters, particularly D-dimer levels. Anticoagulation has been proposed as therapy to decrease mortality, often adjusted for illness severity.

Objective  We wanted to investigate whether anticoagulation improves survival in COVID-19 and if this improvement in survival is associated with disease severity.

Methods  This is a cohort study simulating an intention-to-treat clinical trial, by analyzing the effect on mortality of anticoagulation therapy chosen in the first 48 hours of hospitalization. We analyzed 3,625 COVID-19+ inpatients, controlling for age, gender, glomerular filtration rate, oxygen saturation, ventilation requirement, intensive care unit admission, and time period, all determined during the first 48 hours.

Results  Adjusted logistic regression analyses demonstrated a significant decrease in mortality with prophylactic use of apixaban (odds ratio [OR] 0.46, p  = 0.001) and enoxaparin (OR = 0.49, p  = 0.001). Therapeutic apixaban was also associated with decreased mortality (OR 0.57, p  = 0.006) but was not more beneficial than prophylactic use when analyzed over the entire cohort or within D-dimer stratified categories. Higher D-dimer levels were associated with increased mortality ( p  < 0.0001). When adjusted for these same comorbidities within D-dimer strata, patients with D-dimer levels < 1 µg/mL did not appear to benefit from anticoagulation while patients with D-dimer levels > 10 µg/mL derived the most benefit. There was no increase in transfusion requirement with any of the anticoagulants used.

Conclusion  We conclude that COVID-19+ patients with moderate or severe illness benefit from anticoagulation and that apixaban has similar efficacy to enoxaparin in decreasing mortality in this disease.

Development of a perioperative venous thromboembolism prophylaxis algorithm for pediatric orthopedic surgical patients

Venous thromboembolism (VTE) has been recognized as a rare but potentially serious complication in pediatric orthopedic patients. However, standardized guidelines for screening and management of at-risk patients do not exist. The aim of the study was to develop a VTE prophylaxis screening tool for postoperative orthopedic patients after conducting an institutional needs assessment survey. A needs assessment survey was conducted after institutional ethics board approval. Development of perioperative VTE prophylaxis algorithm for pediatric orthopedic surgical patients was planned after thorough literature review, consultation with national and international experts as well as using a modified nominal and consensus development conference (serial meetings) method for reaching a consensus. NAS as well as discussion with stakeholders indicated support for development of perioperative VTE prophylaxis algorithm for orthopedic patients. Using above methods, a VTE prophylaxis algorithm was developed and implemented at IWK Health Center. The present study involved development of a perioperative VTE prophylaxis algorithm for pediatric orthopedic surgical patients that could be easily and rapidly administered as a point of care assessment tool.

Thromboprophylaxis an update of current practice: Can we reach a consensus?

Diagnosis, prophylaxis, and management of venous thromboembolism (VTE) in patients with fractures remain a highly controversial topic with little consensus in clinical practice or the literature. The following manuscript represents a summary of evidence presented at the 2017 OTA Annual Meeting Symposium; "Thromboprophylaxis an Update of Current Practice: Can We Reach A Consensus?" The need for prophylaxis in pelvic and acetabular fracture patients; the existing body of evidence related to VTE, pulmonary embolism (PE), and prophylaxis for patients with fractures about the knee; current evidence in Edinburgh Scotland, regarding VTE prophylaxis in patients with isolated ankle fractures and the risk of VTE in patients with a hip fracture are topics that are addressed. The reader will benefit from the wisdom of this compilation of global contributions on thromboprophylaxis.

Effectiveness and safety of rivaroxaban for the prevention of thrombosis following total hip or knee replacement: A systematic review and meta-analysis

BACKGROUND

Prophylactic anticoagulant therapy is recommended to reduce the risk of venous thromboembolism (VTE) after total hip or knee arthroplasty, and has become the standard of care. Rivaroxaban is a novel oral medication that directly inhibits factor Xa for the prevention and treatment of thromboembolic conditions.

METHOD

A meta-analysis of randomized controlled trials (RCTs) was performed to determine the efficacy and safety of rivaroxaban after total hip arthroplasty (THA) and total knee arthroplasty (TKA) surgery. We reviewed several databases including PubMed, the Cochrane Library, Embase and the US trial registry to detect appropriate RCTs for our meta-analysis. The primary efficacy outcome of this meta-analysis was the combination of any deep-vein thrombosis (DVT), non-fatal pulmonary embolism (PE), and death from any cause. The main safety outcome was bleeding events which included significant bleeding events, clinically relevant insignificant bleeding events, or minor events. Other end points were the number of patients who received blood transfusion the volume of transfused whole blood or red blood cells, and the volume of postoperative drainage.

RESULT

Thirteen RCTs were included in this meta-analysis. This meta-analysis showed that the overall rate of VTE events, DVT, PE, and death were 1%, 6%, < 1% and < 1%, respectively, for patients receiving treatment with rivaroxaban after THA and TKA surgery. The subgroup analysis demonstrated rivaroxaban had more superior effects in THA patients. The pooled analysis of bleeding events showed that the overall rate of major bleeding events, overt bleeding events associated with fall in Hb of > 2 g/DL, clinically overt bleeding events leading to transfusion of > 2 units of blood, clinically overt bleeding events leading to further surgeries, and non-major bleeding events were < 1%, < 1%, < 1%, < 1%, and 3%, respectively.

CONCLUSION

This is the first systematic review of the literature providing incidence of efficacy and safety outcomes for thromboprophylaxis in THA and TKA patients. Moreover, this meta-analysis showed that rivaroxaban had more superior effect in THA patients.

Aspirin versus rivaroxaban in postoperative bleeding after total knee arthroplasty: a retrospective case-matched study

BACKGROUND

Venous thromboembolic disease (VTE) is a complication not uncommon following total knee arthroplasty. Postoperative bleeding-related complications are a concern in many guidelines. The authors aimed to compare the amount of postoperative drainage from closed suction drainage, transfusion rate, and postoperative complications between aspirin and rivaroxaban as VTE prophylaxes after total knee arthroplasty.

METHODS

This study was a retrospective case-matched study of 155 patients. The data were collected between 2008 and 2015 from patients who had total knee arthroplasty using aspirin or rivaroxaban as the VTE prophylaxis. Seventy-nine patients received aspirin, and 76 patients received rivaroxaban. A single surgeon operated on all patients with the same surgical technique and patient care protocol.

RESULTS

The total closed suction drainage outputs at 48 h were not significantly different between the aspirin and rivaroxaban groups (p = 0.10). Eighteen percent of patients in the aspirin group and 25% of patients in the rivaroxaban group received blood transfusions (p = 0.37). There were no bleeding-related complications or VTE in either group.

CONCLUSIONS

Aspirin and rivaroxaban were effective and safe as VTE chemoprophylaxis in total knee arthroplasty.

Low-molecular-weight heparin for hip fracture patients treated with osteosynthesis: should thromboprophylaxis start before or after surgery? An observational study of 45,913 hip fractures reported to the Norwegian Hip Fracture Register

Background and purpose - Controversies exist regarding thromboprophylaxis in orthopedic surgery. We studied whether the thromboprophylaxis in hip fracture patients treated with osteosynthesis should start preoperatively or postoperatively. Data were extracted from the nationwide Norwegian Hip Fracture Register (NHFR). The risks of postoperative deaths, reoperations, and intraoperative bleeding were studied within 6 months after surgery. Patients and methods - After each operation for hip fracture in Norway the surgeon reports information on the patient, the fracture, and the operation to the NHFR. Cox regression analyses were performed with adjustments for age group, ASA score, sex, duration of surgery, and year of surgery. During the period 2005-2016, 96,599 hip fractures were reported to the register. Only osteosyntheses where low-molecular-weight heparin (LMWH) were given and with known information on preoperative start of the prophylaxis were included in the analyses. Dalteparin and enoxaparin were used in 58% and 42% of the operations respectively (n = 45,913). Results - Mortality (RR =1.01, 95% CI 0.97-1.06) and risk of reoperation (RR =0.99, CI 0.90-1.08) were similar comparing preoperative and postoperative start of LMWH. Postoperative start reduced the risk of intraoperative bleeding complications compared with preoperative start (RR =0.67, CI 0.51-0.90). Interpretation - The initiation of LMWH did not influence the mortality or the risk of reoperation in hip fracture patients treated with osteosynthesis. Postoperative start of LMWH could possibly decrease the risk of intraoperative bleeding.

Comparative efficacy and safety of anticoagulants for prevention of venous thromboembolism after hip and knee arthroplasty

Background and purpose - New oral anticoagulants have been developed to prevent venous thromboembolism (VTE) after knee or hip arthroplasty. Although there have been several network meta-analyses (NMA) to compare different regimens, an NMA including 2 different enoxaparin doses and edoxaban has not been performed. Methods - Standard NMA for fondaparinux, dabigatran, rivaroxaban, apixaban, edoxaban, and enoxaparin was performed. Outcome variables included a composite of total VTE and major/clinically relevant bleeding. The rank probabilities of each treatment outcome were summarized by the surface under the cumulative ranking curve. Results - Fondaparinux, rivaroxaban, and apixaban were associated with a reduced risk of VTE compared with enoxaparin, while dabigatran was not. None of these 3 drugs increased bleeding compared with enoxaparin 30 mg twice daily. However, fondaparinux and rivaroxaban increased bleeding compared with enoxaparin 40 mg once daily, while apixaban did not. Apixaban was even associated with decreased major/clinically relevant bleeding compared with enoxaparin 30 mg twice daily or 40 mg once daily. When edoxaban was included in the NMA, edoxaban decreased VTE and did not increase bleeding compared with enoxaparin. Interpretation - A higher efficacy of fondaparinux and rivaroxaban compared with enoxaparin was associated with increased bleeding tendency, while apixaban was superior to enoxaparin regarding both efficacy and safety. A clustered ranking plot showed that apixaban might be the most preferred regarding efficacy and safety. However, our results were driven by indirect statistical inference and were limited by the heterogeneity of the bleeding outcome definitions, drug initiation and continuation, and different surgery types.

Low-Molecular-Weight Heparin and the Relative Risk of Surgical Site Bleeding Complications: Results of a Systematic Review and Meta-Analysis of Randomized Controlled Trials of Venous Thromboprophylaxis in Patients After Total Joint Arthroplasty

BACKGROUND

Venous thromboembolism causes significant morbidity and mortality in patients after total joint arthroplasty. Although network meta-analyses have demonstrated a benefit of various thromboprophylactic agents, there remains a concern in the surgical community regarding the resulting wound complications. There is currently no systematic review of the surgical site bleeding complications of thromboprophylactic agents. The aim of this study was to systematically review the surgical site bleeding outcomes of venous thromboembolism prophylaxis in this population.

METHODS

A systematic review and meta-analysis was performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Randomized controlled trials comparing more than one of low-molecular-weight heparin (LMWH), warfarin, rivaroxaban, apixaban, dabigatran, aspirin, or no pharmacologic treatment in patients after total hip or knee arthroplasty were selected for inclusion. Five meta-analyses were performed to compare LMWH with control, warfarin, apixaban, rivaroxaban, and dabigatran.

RESULTS

Forty-five randomized controlled trials of 56,730 patients were included. LMWH had a significantly increased relative risk of surgical site bleeding in comparison with control (relative risk, 2.32; 95% confidence interval, 1.40-3.85) and warfarin (1.54; 1.23-1.94). The relative risk of LMWH trended higher than apixaban (1.27; 1.00-1.63) and was similar to rivaroxaban (0.95; 0.74-1.23). Only 1 study reported the risk of surgical site bleeding in LMWH vs dabigatran (5.97; 2.08-17.11).

CONCLUSION

LMWH increased the risk of surgical site bleeding compared with control, warfarin. and dabigatran and trended toward an increased risk compared with apixaban. The risk of surgical site bleeding was similar with LMWH and rivaroxaban.

Pharmacology of Heparin and Related Drugs

Heparin has been recognized as a valuable anticoagulant and antithrombotic for several decades and is still widely used in clinical practice for a variety of indications. The anticoagulant activity of heparin is mainly attributable to the action of a specific pentasaccharide sequence that acts in concert with antithrombin, a plasma coagulation factor inhibitor. This observation has led to the development of synthetic heparin mimetics for clinical use. However, it is increasingly recognized that heparin has many other pharmacological properties, including but not limited to antiviral, anti-inflammatory, and antimetastatic actions. Many of these activities are independent of its anticoagulant activity, although the mechanisms of these other activities are currently less well defined. Nonetheless, heparin is being exploited for clinical uses beyond anticoagulation and developed for a wide range of clinical disorders. This article provides a "state of the art" review of our current understanding of the pharmacology of heparin and related drugs and an overview of the status of development of such drugs.

Tranexamic Acid Tamponade to Control Postoperative Surgical Hemorrhage

When preparing for oral surgery, patients taking anticoagulants usually should not discontinue their medication because of the risk of a thromboembolic event. The therapeutic effect of many anticoagulants is not readily measured, so preoperatively, the surgeon cannot know the true risk for postoperative hemorrhage. The risk of a thromboembolic event usually outweighs the concerns of controlling postoperative hemorrhage. Hemophilia patients are also at risk for postoperative bleeding. Single extractions probably do not pose a serious risk for postoperative hemorrhage. However, when a mucogingival flap is raised in these patients, there may be prolonged bleeding. Surgical sponges saturated with aqueous tranexamic acid solution and compressed onto the bleeding site with biting pressure may stop bleeding. Bleeding was stopped in the case example presented here after three 10-minute compressions over 30 minutes in a patient taking aspirin and clopidogrel for a previous thromboembolic event and a metal coronary stent. The clot formed is very fragile and is prone to bleeding, so it should not be disturbed. This technique needs to be studied for efficacy.

The relationships among hemostatic markers, the withdrawal of fondaparinux due to a reduction in hemoglobin and deep vein thrombosis in Japanese patients undergoing major orthopedic surgery

BACKGROUND

The relationships among the hemostatic markers, the development of deep vein thrombosis (DVT) and the withdrawal of fondaparinux due to a reduction in the hemoglobin levels were examined.

METHODS

Two-hundred twenty-one Japanese patients who underwent major orthopedic surgery and were treated with 1.5mg of fondaparinux instead of 2.5mg of fondaparinux were studied. Forty-seven of 221 patients discontinued fondaparinux treatment (withdrawal group) and 37 patients developed DVT.

RESULTS

The age, frequency of total knee arthroplasty (TKA), withdrawal of fondaparinux, reduction of hemoglobin and the plasma levels of soluble fibrin (SF), D-dimer and fibrinogen and fibrin degradation product (FDP) on day 1 after the operation were significantly higher in the patients with DVT. Elevated SF, D-dimer or FDP levels were associated with the risk for DVT. The age, frequency of TKA or DVT, anti-Xa activity and the creatinine, FDP and D-dimer levels were significantly higher in the withdrawal group. An anti-Xa level >0.33 mg/l and an elevated D-dimer or FDP level were associated with the risk of withdrawal.

CONCLUSION

The age and SF levels, TKA and withdrawal of fondaparinux were related to the risk of DVT, and the anti-Xa activity, creatinine level and DVT were related to the risk of withdrawal of fondaparinux due to a reduction in hemoglobin.

Perioperative Thromboprophylaxis

<b><i>Background: </i></b>Venous thromboembolism (VTE), a composite of deep vein thrombosis and pulmonary embolism, is a preventable cause of morbidity and mortality in surgical patients. <b><i>Method: </i></b>National and international treatment guidelines and major clinical trials on mechanical or pharmacological VTE prophylaxis in surgical patients were reviewed. <b><i>Results: </i></b>The risk of perioperative VTE is dependent on patient- and surgery-related risk factors. Based on a thorough and individualized risk assessment, each surgical patient should be assigned a low, intermediate, or high risk of VTE. Whereas basic (e.g. early mobilization and avoidance of dehydration) and mechanical (i.e. graduated compression stockings) measures are appropriate for most low-risk patients, visceral surgical patients at intermediate or high risk of VTE should receive pharmacological thromboprophylaxis for at least 7-10 days. The risk of VTE should be balanced against the risk of bleeding. Low-molecular-weight heparin (LMWH) offers several advantages over low-dose unfractionated heparin and should be administered for prolonged periods in patients undergoing particularly high-risk (i.e. cancer) surgery. <b><i>Conclusion: </i></b>Perioperative VTE prophylaxis should be carried out in an individualized and risk-adapted manner. In visceral surgical patients with a moderate-to-high risk of VTE and a low risk of bleeding, pharmacological thromboprophylaxis with LMWH is a standard of care.