Rivaroxaban versus enoxaparin for thromboprophylaxis after total hip or knee arthroplasty: a meta-analysis of randomized controlled trials

Efficacy and Safety of Rivaroxaban and Enoxaparin for Thromboprophylaxis Among Total Hip Arthroplasty Patients: A Systematic Review and Meta-Analysis

BACKGROUND

Venous thromboembolism (VTE) is one of the major and potentially life-threatening complications following major orthopedic surgeries. Research evidence comparing the effectiveness of rivaroxaban and enoxaparin for thromboprophylaxis specific to total hip arthroplasty (THA) has been limited. Hence, this review was done to compare the efficacy and safety of rivaroxaban against enoxaparin for thromboprophylaxis after THA.

MATERIALS AND METHODS

We conducted a search in databases including Medline, EMBASE, ScienceDirect, Google Scholar, and Cochrane Library from inception until May 2021. Randomized controlled trials directly comparing the effectiveness of rivaroxaban and enoxaparin for thromboprophylaxis among patients undergoing THA were eligible for inclusion. Outcome parameters assessed were efficacy in terms of total VTE and all-cause mortality, major VTE, deep vein thrombosis, symptomatic VTE, and safety in terms of major bleeding events, clinically relevant nonmajor bleeding events, minor bleeding events, total bleeding events, drug-related adverse events, and wound infection. We performed a meta-analysis with a random effects model and reported a pooled risk ratio (RR) with a 95% confidence interval (CI).

RESULTS

Eleven studies, including 9057 participants, were analyzed. Amongst efficacy outcomes, VTE and all-cause mortality pooled an RR of 0.58 (95% CI: 0.34-0.99), major VTE pooled an RR of 0.37 (95% CI: 0.15-0.90), deep vein thrombosis pooled an RR of 0.57 (95% CI: 0.32-1.02), and symptomatic VTE pooled an RR of 0.51 (95% CI: 0.30-0.87). Amongst safety outcomes, major bleeding events pooled an RR of 1.18 (95% CI: 0.77-1.80), total bleeding events pooled an RR of 1.12 (95% CI: 0.93-1.34), drug-related adverse event pooled an RR of 0.99 (95% CI: 0.87-1.12), and wound infection pooled an RR of 1.11 (95% CI: 0.58-2.14).

CONCLUSION

Rivaroxaban is a more efficacious drug in terms of VTE and all-cause mortality compared to enoxaparin following THA, and rivaroxaban was non-inferior in terms of safety profiles such as wound infection, bleeding, and drug-related adverse events.

Antithrombotic prophylaxis following total knee arthroplasty: a level I Bayesian network meta-analysis

INTRODUCTION

Venous thromboembolism (VTE) is a major concern following total knee arthroplasty (TKA). The optimal pharmacological prophylaxis remains, however, controversial. The present investigation compared several non-vitamin K antagonist oral anticoagulants commonly employed as VTE prophylaxis following TKA. A Bayesian network meta-analysis was conducted to compare apixaban, aspirin, dabigatran, edoxaban, enoxaparin, fondaparinux, and rivaroxaban. The outcomes of interest were to compare the rate of deep venous thrombosis (DVT), pulmonary embolism (PE), and major and minor haemorrhages.

METHODS

This study was conducted according to the PRISMA Extension Statement for Reporting of Systematic Reviews Incorporating Network Meta-Analyses of Health Care Interventions. In March 2024, PubMed, Web of Science, and Google Scholar were accessed with no time constraints. All randomised controlled trials (RCTs) comparing two or more drugs for the prevention of VTE following TKA were considered for inclusion.

RESULTS

Data from 29,678 patients were collected. Of them, 67% (19,884 of 29,678 patients) were women. The mean age of the patients was 66.8 ± 2.8 years, and the mean BMI was 29.2 ± 1.5 kg/m2. There was comparability in age, sex, and BMI at baseline. Apixaban 5 mg, dabigatran 220 mg, and rivaroxaban 10 mg were the most effective in reducing the rate of DVT. Apixaban 5 mg, enoxaparin 60 mg, and rivaroxaban 40 mg were the most effective in reducing the rate of PE. Apixaban 5 mg, rivaroxaban 10 mg, and apixaban 10 mg were associated with the lowest rate of major haemorrhages. Apixaban 5 mg and 20 mg, and dabigatran 220 mg were associated with the lowest rate of minor haemorrhages.

CONCLUSION

Administration of apixaban 5 mg demonstrated the best balance between VTE prevention and haemorrhage control following TKA.

LEVEL OF EVIDENCE

Level I, network meta-analysis of RCTs.

Antithrombotic prophylaxis following total hip arthroplasty: a level I Bayesian network meta-analysis

BACKGROUND

Several clinical investigations have compared different pharmacologic agents for the prophylaxis of venous thromboembolism (VTE). However, no consensus has been reached. The present investigation compared enoxaparin, fondaparinux, aspirin and non-vitamin K antagonist oral anticoagulants (NOACs) commonly used as prophylaxis following total hip arthroplasty (THA). A Bayesian network meta-analysis was performed, setting as outcomes of interest the rate of deep venous thrombosis (DVT), pulmonary embolism (PE) and major and minor haemorrhages.

METHODS

This study was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) extension statement for reporting systematic reviews incorporating network meta-analyses of healthcare interventions. All randomised controlled trials (RCTs) comparing two or more drugs used for the prophylaxis of VTE following THA were accessed. PubMed, Web of Science and Google Scholar databases were accessed in March 2023 with no time constraint.

RESULTS

Data from 31,705 patients were extracted. Of these, 62% (19,824) were women, with age, sex ratio, and body mass index (BMI) being comparable at baseline. Apixaban 5 mg, fondaparinux, and rivaroxaban 60 mg were the most effective in reducing the rate of DVT. Dabigatran 220 mg, apixaban 5 mg, and aspirin 100 mg were the most effective in reducing the rate of PE. Apixaban 5 mg, ximelagatran 2 mg and aspirin 100 mg were associated with the lowest rate of major haemorrhages, while rivaroxaban 2.5 mg, apixaban 5 mg and enoxaparin 40 mg were associated with the lowest rate of minor haemorrhages.

CONCLUSION

Administration of apixaban 5 mg demonstrated the best balance between VTE prevention and haemorrhage control following THA. Level of evidence Level I, network meta-analysis of RCTs.

Comparative effectiveness of aspirin for symptomatic venous thromboembolism prophylaxis in patients undergoing total joint arthroplasty, a cohort study

BACKGROUND

This study compares the symptomatic 90-day venous thromboembolism (VTE) rates in patients receiving aspirin to patients receiving low-molecular weight heparin (LMWH) or direct oral anticoagulants (DOACs), after total hip (THA) and total knee arthroplasty (TKA).

METHODS

Data were collected from a multi-centre cohort study, including demographics, confounders and prophylaxis type (aspirin alone, LMWH alone, aspirin and LMWH, and DOACs). The primary outcome was symptomatic 90-day VTE. Secondary outcomes were major bleeding, joint related reoperation and mortality within 90 days. Data were analysed using logistic regression, the Student's t and Fisher's exact tests (unadjusted) and multivariable regression (adjusted).

RESULTS

There were 1867 eligible patients; 365 (20%) received aspirin alone, 762 (41%) LMWH alone, 482 (26%) LMWH and aspirin and 170 (9%) DOAC. The 90-day VTE rate was 2.7%; lowest in the aspirin group (1.6%), compared to 3.6% for LMWH, 2.3% for LMWH and aspirin and 2.4% for DOACs. After adjusted analysis, predictors of VTE were prophylaxis duration < 14 days (OR = 6.7, 95% CI 3.5-13.1, p < 0.001) and history of previous VTE (OR = 2.4, 95% CI 1.1-5.8, p = 0.05). There were no significant differences in the primary or secondary outcomes between prophylaxis groups.

CONCLUSIONS

Aspirin may be suitable for VTE prophylaxis following THA and TKA. The comparatively low unadjusted 90-day VTE rate in the aspirin group may have been due to selective use in lower-risk patients.

TRIAL REGISTRATION

This study was registered at ClinicalTrials.gov, trial number NCT01899443 (15/07/2013).

The impact of adopting low-molecular-weight heparin in place of aspirin as routine thromboprophylaxis for patients with hip fracture

PURPOSE OF THE STUDY

In 2010, the National Institute for Health and Care Excellence (NICE) recommended the use of anticoagulants rather than aspirin as pharmacological thromboprophylaxis after hip fracture. We examine the impact of implementing this change in guidance on the clinical incidence of deep vein thrombosis (DVT).

STUDY DESIGN

Demographic, radiographic and clinical data were retrospectively collected for 5039 patients admitted to a single tertiary centre in the UK for hip fracture between 2007 and 2017. We calculated rates of lower-limb DVT and examined the impact of the June 2010 change of departmental policy, from use of aspirin to use of low-molecular-weight heparins (LMWH) in hip fracture patients.

RESULTS

Doppler scans were performed in 400 patients in the 180 days after a hip fracture, and identified 40 ipsilateral and 14 contralateral DVTs (p<0.001). The rate of DVT reduced significantly following the 2010 change in departmental policy from aspirin to LMWH in these patients (1.62% vs 0.83%, p<0.05).

CONCLUSIONS

The rate of clinical DVT halved following the change from aspirin to LMWH for pharmacological thromboprophylaxis, but the number needed to treat was 127. A figure of <1% for the incidence of clinical DVT in a unit that routinely uses LMWH monotherapy following hip fracture provides a context for discussions of alternative strategies, and for power calculations for future research. These figures are important to policy makers and to researchers as they will inform the design of the comparative studies on thromboprophylaxis agents for which NICE has called.

Changes in Thromboelastography to Predict Ecchymosis After Knee Arthroplasty: A Promising Guide for the Use of Anticoagulants

Background

Ecchymosis is one of the worrisome complications after total knee arthroplasty (TKA) and interferes with functional rehabilitation. Current clinical guidelines do not provide individualized approaches for patients with ecchymoses.

Methods

In this study, we used thromboelastography (TEG) to determine the coagulation state after TKA and to then explore markers that predict the occurrence of ecchymosis events after TKA. In our cohort, patients were divided into ecchymosis (n = 55) and non-ecchymosis (n = 137) groups according to whether ecchymosis events occurred after TKA. Rivaroxaban 10 mg/d was taken orally for thromboprophylaxis after surgery. All patients completed TEG testing. Correlation analysis was used to determine the risk factors for ecchymosis after TKA, and receiver operating characteristic (ROC) curves for variables with significant correlation were plotted.

Results

In all, 55 of the 192 patients (28.65%) developed ecchymosis surrounding the surgical site. Multivariate analysis showed that hidden blood loss (OR = 1.003 and p = 0.005) and changes in the coagulation index (ΔCI) values (OR = 0.351 and p = 0.001) were risk factors for ecchymosis after TKA. Using the Youden index, 0.1805 was determined as the optimal threshold value of ΔCI for predicting the occurrence of ecchymosis, with a sensitivity of 74.55% and specificity of 72.99%. ΔCI is a promising marker as an alarm for the occurrence of ecchymosis after TKA.

Trial Registration

The study was registered in the Chinese Clinical Trial Registry (ChiCTR1800017245). Registered name: The role of thrombelastography in monitoring the changes of coagulation function during perioperative period of arthroplasty. Registered 19 July 2018. http://www.chictr.org.cn/showproj.aspx?proj=29220

Efficacy and Safety of Enoxaparin versus New Oral Anticoagulants to Prevent Venous Thromboembolism after Total Hip Replacement: A Systematic Review and Meta-Analysis

Prophylactic anticoagulant therapy is recommended for reducing the risk of venous thromboembolism (VTE) after a total hip replacement (THR). However, it is not clear which anticoagulant is preferable. Hence, a systematic review and meta-analysis of randomized double-blind controlled trials (RDBCTs) were conducted to investigate the clinical efficacy and safety of enoxaparin in comparison with newer oral anticoagulants for the prevention of VTE after THR. The Cochrane Library, Scopus, Web of Science, Embase, and PubMed/Medline databases were used for PICO search strategy. Relative risks (RR) of symptomatic VTE, clinically relevant bleeding, mortality, and a net clinical endpoint were estimated employing a random effect meta-analysis. ITC and RevMan software were used for indirect and direct comparisons, respectively. Nine RDBCTs comprising 24,584 patients were included. As compared to enoxaparin, a reduced risk for symptomatic VTE was observed with rivaroxaban (confidence interval [CI]: 0.32–0.77; RR: 0.46%) and comparable with apixaban (0.12–1.26; 0.42%) and dabigatran (0.22–2.20; 0.70%). Contrarily to enoxaparin, a greater risk for clinically relevant bleeding was observed with rivaroxaban (1.03–1.48; 1.23%), comparable with dabigatran (0.96–1.33; 1.10%) and reduced with apixaban (0.19–5.66; 0.96%). In indirect or direct comparisons, the interventions did not differ on the net clinical endpoint. In conclusion, the findings of this meta-analysis revealed no significant difference in the efficacy and safety of new oral anticoagulants as compared to enoxaparin for the prevention of VTE after total hip replacement surgery.

CRISTAL (a cluster-randomised, crossover, non-inferiority trial of aspirin compared to low molecular weight heparin for venous thromboembolism prophylaxis in hip or knee arthroplasty, a registry nested study): statistical analysis plan

BACKGROUND

This a priori statistical analysis plan describes the analysis for CRISTAL.

METHODS

CRISTAL (cluster-randomised, crossover, non-inferiority trial of aspirin compared to low molecular weight heparin for venous thromboembolism prophylaxis in hip or knee arthroplasty, a registry nested study) aims to determine whether aspirin is non-inferior to low molecular weight heparin (LMWH) in preventing symptomatic venous thromboembolism (VTE) following hip arthroplasty (HA) or knee arthroplasty (KA). The study is nested within the Australian Orthopaedic Association National Joint Replacement Registry. The trial was commenced in April 2019 and after an unplanned interim analysis, recruitment was stopped (December 2020), as the stopping rule was met for the primary outcome. The clusters comprised hospitals performing > 250 HA and/or KA procedures per annum, whereby all adults (> 18 years) undergoing HA or KA were recruited. Each hospital was randomised to commence with aspirin, orally, 85-150 mg daily or LMWH (enoxaparin), 40 mg, subcutaneously, daily within 24 h postoperatively, for 35 days after HA and 14 days after KA. Crossover was planned once the registration target was met for the first arm. The primary end point is symptomatic VTE within 90 days. Secondary outcomes include readmission, reoperation, major bleeding and death within 90 days, and reoperation and patient-reported pain, function and health status at 6 months. The main analyses will focus on the primary and secondary outcomes for patients undergoing elective primary total HA and KA for osteoarthritis. The analysis will use an intention-to-treat approach with cluster summary methods to compare treatment arms. As the trial stopped early, analyses will account for incomplete cluster crossover and unequal cluster sizes.

CONCLUSIONS

This paper provides a detailed statistical analysis plan for CRISTAL.

TRIAL REGISTRATION

Australian and New Zealand Clinical Trials Registry ACTRN12618001879257 . Registered on 19/11/2018.

A retrospective analysis of bleeding risk with rivaroxaban, enoxaparin, and aspirin following total joint arthroplasty or revision

STUDY OBJECTIVE

Rivaroxaban, enoxaparin, and aspirin are commonly used medications for thromboprophylaxis following lower extremity joint arthroplasty or revision. Previous research has demonstrated efficacy in preventing venous thromboembolism with each medication, however, the comparative risk of bleeding between them remains poorly understood. The aim of this study was to compare the odds of bleeding between rivaroxaban, enoxaparin, and aspirin following lower extremity joint arthroplasty or revision.

DESIGN

This is a 3-year retrospective cohort study.

SETTING

Data were obtained from 148 facilities across 55 states and territories of the United States.

PATIENTS

This study included 85,938 patients who underwent hip or knee arthroplasty or revision.

INTERVENTION

Patients received enoxaparin, rivaroxaban, or aspirin as monotherapy for thromboprophylaxis.

MEASUREMENTS

The primary outcome was all bleeding, classified as major or minor bleeding, occurring in the 40 days following surgery. The secondary outcome was venous thromboembolism.

MAIN RESULTS

Among 85,938 patients, 10,465 received rivaroxaban, 14,047 received enoxaparin, and 61,426 received aspirin. Bleeding occurred in 126 (1.20%) patients with rivaroxaban, 253 (1.80%) with enoxaparin, and 611 (0.99%) with aspirin. There was a significant increase in odds of bleeding in the enoxaparin compared to aspirin group odds ratio (OR) 1.18, 95% confidence interval (CI) 1.01-1.38, p = 0.042), and a trend toward increased odds of bleeding in rivaroxaban compared to aspirin group (OR 1.21, 95% CI 0.99-1.47, p = 0.058) and rivaroxaban compared to enoxaparin (OR 1.03, 95% CI 0.82-1.28, p = 0.827). Odds of venous thromboembolism were not statistically significant between all three study medications.

CONCLUSIONS

Among rivaroxaban, enoxaparin, and aspirin used for thromboprophylaxis in knee and hip arthroplasty or revision, aspirin had significantly decreased odds of bleeding complications compared to enoxaparin. Although not statistically significant, aspirin also had a trend toward decreased odds of bleeding complications compared to rivaroxaban. Our study results suggest that aspirin is a safer alternative for use in postoperative thromboprophylaxis following lower extremity joint arthroplasty or revision.

Aspirin versus enoxaparin for the initial prevention of venous thromboembolism following elective arthroplasty of the hip or knee: A systematic review and meta-analysis

BACKGROUND

Aspirin is perceived to be non-inferior to enoxaparin, a low-molecular-weight heparin, for the prevention of venous thromboembolism (VTE) following elective arthroplasty of the hip or knee and is recommended in clinical guidelines internationally. Previous systematic reviews of aspirin as VTE prophylaxis have been limited by the inclusion of heterogenous studies where aspirin is commenced after the initial high-risk postoperative period. The purpose of this systematic review and meta-analysis was to compare the efficacy and associated harms of aspirin and enoxaparin when used as VTE prophylaxis in the initial postoperative period following elective arthroplasty of the hip or knee. We sought to: (1) to compare the use of aspirin versus enoxaparin following elective joint replacement of the hip or knee on the primary outcomes of incidence of VTE and mortality up to 3 months postoperatively and (2) assess the efficacy of aspirin with respect to secondary outcomes such as major or minor bleeding events. We hypothesised that aspirin would have equivalent efficacy for the prevention of VTE when used as initial prophylactic agent, without increasing harm from bleeding events.

PATIENTS AND METHODS

We searched Pubmed, Embase, Medline and Cochrane Central for randomized controlled trials reporting the primary outcomes of VTE incidence and mortality. Secondary outcomes included major (compromise of organ, limb or muscle function requiring unplanned re-operation) and minor bleeding events (wound ooze, minor bleed, infection). Included trials underwent a risk of bias and quality of evidence assessment using the GRADE criteria.

RESULTS

Four trials involving 1507 participants who underwent elective lower limb arthroplasty were included. We did not detect a significant difference in overall VTE rates when comparing aspirin versus enoxaparin (RR, 0.84; 95% CI: 0.41 to 1.75; p=0.65). Mortality was reported by one study and no events were recorded. There were no significant differences in the rates of all major (RR, 0.84; 95% CI: 0.08 to 9.16) or minor (RR, 0.77; 95% CI: 0.34 to 1.72) bleeding events between the aspirin and enoxaparin groups. Included trials demonstrated a significant risk of bias, and Low to Very Low quality of evidence for primary outcomes, and Moderate to Very Low for secondary outcomes.

CONCLUSION

There is currently a lack of high quality randomised controlled trials supporting the use of aspirin as VTE chemoprophylaxis in the initial postoperative period for both total hip and total knee arthroplasty. The results of this meta-analysis provide cautious endorsement for the position that aspirin is likely a safe alternative to enoxaparin for TKA patients as part of a multimodal enhanced recovery protocol, but care is advised for THA patients owing to a lack of data from trials. Current evidence from randomized controlled trials is generally of low quality, and does not estimate critical event data for VTE incidence or mortality, as well as major and minor bleeding events with sufficient certainty. PROSPERO Registration CRD42018110784.

LEVEL OF EVIDENCE

II, systematic review.

[Perioperative Venous Thromboembolism (VTE) Prophylaxis in Thoracic Cancer Patients: Chinese Experts Consensus - Interpretation of Application Prospect of Direct Oral Anticoagulant]

胸部恶性肿瘤患者围术期静脉血栓栓塞症（venous thromboembolism, VTE）是一种需要引起重视的胸外科围术期并发症，中国胸外科静脉血栓栓塞研究协作组针对胸部恶性肿瘤患者围术期VTE的预防，发布了国际首部《胸部恶性肿瘤围术期静脉血栓栓塞症预防中国专家共识》（2018版）。本文将对直接口服抗凝药在胸部恶性肿瘤患者围术期的应用进行解读，以助于更好地理解共识相关内容。

CRISTAL: protocol for a cluster randomised, crossover, non-inferiority trial of aspirin compared to low molecular weight heparin for venous thromboembolism prophylaxis in hip or knee arthroplasty, a registry nested study

INTRODUCTION

Venous thromboembolism (VTE) is a serious complication following hip arthroplasty (HA) and knee arthroplasty (KA). This study aims to determine whether aspirin is non-inferior to low molecular weight heparin (LMWH) in preventing symptomatic VTE following HA and KA.

METHODS AND ANALYSIS

This is a cluster randomised, crossover, non-inferiority, trial nested within the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR). The clusters will consist of Australian hospitals performing at least 250 HA and/or KA procedures per annum. All adult patients undergoing HA or KA will be included. The intervention will be aspirin, orally, 85-150 mg daily. The comparator will be LMWH (enoxaparin) 40 mg, subcutaneously, daily. Both drugs will commence within 24 hours postoperatively and continue for 35 days after HA and 14 days after KA. Each hospital will be randomised to commence with aspirin or LMWH and then crossover to the alternative treatment after meeting the recruitment target. Data will be collected through the AOANJRR via patient-reported surveys. The primary outcome is symptomatic VTE within 90 days post surgery, verified by AOANJRR staff. The primary analysis will include only patients undergoing elective primary total hip arthroplasty and total knee arthroplasty for osteoarthritis. Secondary outcomes will include symptomatic VTE for all HA and KA (including partial and revision) within 90 days, readmission, reoperation, major bleeding and death within 90 days and reoperation, death and patient-reported pain, function and health status at 6 months. If aspirin is found to be inferior, a cost-effectiveness analysis will be conducted. The study will aim to recruit 15 562 patients from 31 hospitals.

ETHICS AND DISSEMINATION

Ethics approval has been granted. Trial results will be submitted for publication. The trial is registered with the Australian New Zealand Clinical Trials Registry (ACTRN12618001879257, pre-results) and is endorsed by the Australia and New Zealand Musculoskeletal Clinical Trials Network.

Factor Xa Inhibitors and Direct Thrombin Inhibitors Versus Low-Molecular-Weight Heparin for Thromboprophylaxis After Total Hip or Total Knee Arthroplasty: A Systematic Review and Meta-Analysis

BACKGROUND

The purpose of this study is to perform a meta-analysis to compare outcomes of venous thromboembolism (VTE) prophylaxis with low-molecular-weight heparin (LMWH) vs other anticoagulants in patients who received total knee (TKA) or total hip arthroplasty (THA).

METHODS

MEDLINE, Cochrane, EMBASE, and Google Scholar databases were searched until June 30, 2017 for eligible randomized controlled studies.

RESULTS

Thirty-two randomized controlled studies were included. LMWH provided better protection against VTE than placebo. In both TKA and THA patients, the rates of VTE were lower with factor Xa inhibitors than LMWH. In THA patients, the rate of deep vein thrombosis (DVT) was lower with factor Xa inhibitors than LMWH. In TKA patients, the rates of VTE and DVT were similar between LMWH and direct thrombin inhibitors. In THA patients, the rate of VTE was lower with direct thrombin inhibitors than with LMWH, while the DVT rates were similar. The pulmonary embolism rates were similar between all 3 classes of drugs in TKA and THR patients, as were the major bleeding rates. Nonmajor and minor bleeding rates were also similar between the 3 drug classes.

CONCLUSION

LMWH is associated with a higher rate of VTE than factor Xa inhibitors in TKA and THA patients. Direct thrombin inhibitors are associated with a lower rate of VTE in THA patients, but their effectiveness with respect to DVT and pulmonary embolism prophylaxis is similar to that of LMWH in TKA and THA patients.

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.

A prospective multicenter observational study evaluating the risk of periendoscopic events in patients using anticoagulants: the Osaka GIANT Study

Background and study aims  An increasing number of patients have been using anticoagulants including anti-vitamin K antagonists (VKAs) and direct oral anticoagulants (DOACs); however, in patients using anticoagulants, limited data are available with regard to the risks of gastrointestinal bleeding and thromboembolic events during the peri-endoscopic period. We aimed to evaluate the peri-endoscopic bleeding and thrombotic risks in patients administered VKAs or DOACs. Patients and methods  Consecutive patients using anticoagulants who underwent endoscopic biopsy, mucosal resection, or submucosal dissection were prospectively enrolled across 11 hospitals. The primary outcome assessed was difference in incidence of post-procedural gastrointestinal bleeding in patients using VKAs and DOACs. Duration of hospitalization and peri-procedural thromboembolic events were also compared. Results  We enrolled 174 patients using VKAs and 37 using DOACs. In total, 16 patients using VKA were excluded from the analysis because of cancellation of endoscopic procedures and contraindications to the use of DOACs; 128 (81 %) patients using VKAs and 17 (46 %) using DOACs received heparin-bridging therapy (HB). The rate of post-procedural gastrointestinal bleeding in DOAC users was similar to that in VKA users (16.2 % vs. 16.4 %, P  = 1.000). Duration of hospitalization was significantly longer in patients using VKAs than in those using DOACs (median 15 vs. 7 days, P  < 0.0001). Myocardial infarction occurred during pre-endoscopic HB in one patient using VKAs. Conclusion  DOAC administration showed similar post-procedural gastrointestinal bleeding risk to VKA administration in patients undergoing endoscopic procedures, but it shortened the hospital stay.

Clinical Impact of Coagulation and Fibrinolysis Markers for Predicting Postoperative Venous Thromboembolism in Total Joint Arthroplasty Patients

One common complication after joint arthroplasty is venous thromboembolism (VTE). Therefore, it is essential to measure the changes in coagulation and fibrinolysis in order to predict VTE among patients who underwent joint arthroplasty. This study aimed to identify potential useful biomarkers for prognosing to VTE. This was a prospective cohort study enrolling 83 patients who underwent joint arthroplasty. The levels of d-dimer, thrombin-antithrombin complex (TAT), plasmin-α2-antiplasmin complex (PIC), soluble thrombomodulin, and tissue plasminogen activator inhibitor complex were measured on day 0 (before surgery) and days 1, 3, and 6 after surgery. Ultrasound examination was used to diagnose VTE on preoperative day 0 and postoperative day 6. A total of 35 patients developed VTE after surgery. Patients with VTE exhibited significantly higher levels of d-dimer and TAT on postoperative days 3 and 6 (all P < .05). The area under curves (AUC) of receiver operating characteristic (ROC) were 0.65 and 0.68 and 0.68 and 0.74 for d-dimer and TAT levels on postoperative days 3 and 6, respectively. The level of TAT/PIC ratio on postoperative day 6 was significantly increased among patients with VTE compared to non-VTE patients (P < .0001). In addition, the AUC of ROC, cutoff level, sensitivity, specificity, positive-predictive value, and negative-predictive value of TAT/PIC ratio were 0.78, 4.03 ng/TU, 97.14%, 33.33%, 51.52%, and 94.12%, respectively. The high sensitivity and negative predictive value of TAT/PIC ratio make it a potential prognostic index for diagnosing VTE during the early phase of postoperative joint arthroplasty.

Comparison of efficiency and safety of rivaroxaban, apixaban and enoxaparin for thromboprophylaxis after arthroplastic surgery: a meta-analysis

OBJECTIVE

To compare the efficacy and safety of rivaroxaban, apixaban and enoxaparin for thromboprophylaxis after arthroplastic surgery.

METHODS

We conducted a meta-analysis containing a wide range of randomized controlled trials about efficiency and safety of rivaroxaban, apixaban and enoxaparin for thromboprophylaxis after arthroplastic surgery in the recent decade from January 2006 to June 2018. The present study separately analyzed the following key components: the different efficiency and safety for rivaroxaban and enoxaparin; apixaban and enoxaparin; and enoxaparin and other new developed anticoagulants.

RESULTS

Sixteen studies containing 58885 patients were included. In results of efficacy outcomes, total events occurred in 4.89% patients of rivaroxaban group and 9.55% patients of the control group; however, no significant difference was observed in apixaban groups of their efficacy outcomes. Primary events didn't show significant difference when comparing apixaban with the control or comparing enoxaparin with the control. In analysis of safety outcomes, bleeding events occurred in 3.41% patients of rivaroxaban group compared with 2.84% patients of the control groups; bleeding events in apixaban groups were 4.09% compared with the control groups 4.64%. Bleeding events occurred in 3.51% patients of enoxaparin group, slightly lower than 5.82% of the control group.

CONCLUSION

Direct oral anticoagulant, rivaroxaban might have better efficacy outcomes in thromboprophylaxis after arthroplastic surgery; however, apixaban showed no significantly different efficacy outcomes compared with enoxaparin, and enoxaparin may have equal or even better safety outcomes compared with direct oral anticoagulants.

The Application of Thromboelastography in Understanding and Management of Ecchymosis After Total Knee Arthroplasty

BACKGROUND

Ecchymosis is a common complication after total knee arthroplasty (TKA). However, only a few studies have been conducted to determine the coagulation status of these patients. Using thromboelastography (TEG), a new technique recording the viscoelastic changes of a whole-blood sample, this study was performed to understand the ecchymosis-related coagulation status and its risk factors.

METHODS

Seventy-five patients receiving unilateral TKA were recruited in this observational study. Oral rivaroxaban was applied as prophylaxis treatment after surgery. TEG was performed 1 day before surgery and 4 days after surgery. Total blood loss and hidden blood loss were recorded and calculated. Univariate and multivariate analyses were conducted to determine risk factors.

RESULTS

Twenty-five patients (33.3%) developed ecchymosis within 2-3 days after TKA. Compared with the baseline before TKA, the α-angle (P = .032) and calculated coagulation index (CI; P = .012) were increased in non-ecchymosis group, whereas in the ecchymosis group, there was no significant difference regarding any variable of postoperative TEG evaluation. The ecchymosis group exhibited more hidden blood loss (P = .007) and total blood loss (P = .011). Value change of CI (OR = 0.666, 95% confidence interval = [0.496, 0.895], P = .007) and hidden blood loss (OR = 1.008, 95% confidence interval = [1.002, 1.013], P = .004) were recognized as the independent risk factors for postoperative ecchymosis.

CONCLUSION

In TEG evaluation, the value change of CI and hidden blood loss are independent risk factors of ecchymosis. In view of the relative hypocoagulation status, it is reasonable to stop anticoagulation therapy in patients with excessive ecchymosis. Personalized anticoagulation therapy may be helpful for managing ecchymosis after TKA.

Low molecular weight heparin versus other anti-thrombotic agents for prevention of venous thromboembolic events after total hip or total knee replacement surgery: a systematic review and meta-analysis

Background

Venous thromboembolism (VTE) is an important complication following total hip replacement (THR) and total knee replacement (TKR) surgeries. Aim of this study was to comprehensively compare the clinical outcomes of low-molecular-weight heparin (LMWH) with other anticoagulants in patients who underwent TKR or THR surgery.

Methods

Medline, Cochrane, EMBASE, and Google Scholar databases were searched for eligible randomized controlled studies (RCTs) published before June 30, 2017. Meta-analyses of odds ratios were performed along with subgroup and sensitivity analyses.

Results

Twenty-one RCTs were included. In comparison with placebo, LMWH treatment was associated with a lower risk of VTE and deep vein thrombosis (DVT) (P values < 0.001) but similar risk of pulmonary embolism (PE) (P = 0.227) in THR subjects. Compared to factor Xa inhibitors, LMWH treatment was associated with higher risk of VTE in TKR subjects (P < 0.001), and higher DVT risk (P < 0.001) but similar risk of PE and major bleeding in both THR and TKR. The risk of either VTE, DVT, PE, or major bleeding was similar between LMWH and direct thrombin inhibitors in both THR and TKR, but major bleeding was lower with LMWH in patients who underwent THR (P = 0.048).

Conclusion

In comparison with factor Xa inhibitors, LMWH may have higher risk of VTE and DVT, whereas compared to direct thrombin inhibitors, LMWH may have lower risk of major bleeding after THR or TKR.

Electronic supplementary material

The online version of this article (10.1186/s12891-018-2215-3) contains supplementary material, which is available to authorized users.

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.

Direct Oral Anticoagulants Vs. Enoxaparin for Prevention of Venous Thromboembolism Following Orthopedic Surgery: A Dose-Response Meta-analysis

We carried out a dose–response model‐based meta‐analysis to assess venous thromboembolism (VTE) and bleeding with factor Xa (FXa) inhibitors (apixaban, edoxaban, rivaroxaban) and a thrombin inhibitor (dabigatran) compared with European (EU) (40 mg q.d.) and North American (NA) (30 mg Q12H) dose regimens of a low molecular weight heparin (enoxaparin) following orthopedic surgery. Statistically significant differences in both VTE and bleeding outcomes were found between the NA and EU doses of enoxaparin, with odds ratios (95% confidence interval) for the NA vs. EU dose of 0.73 (0.71–0.76) and 1.20 (1.14–1.29) for total VTE and major bleeding, respectively. At approved doses, estimated odds ratios vs. both doses of enoxaparin for the three FXa inhibitors (range: 0.35–0.75 for VTE; 0.76–1.09 for bleeding) compared with those for dabigatran (range: 0.66–1.21 for VTE; 1.10–1.38 for bleeding) suggested generally greater efficacy and less bleeding for the FXa inhibitors.

Primary Joint Arthroplasty Surgery: Is the Risk of Major Bleeding Higher in Elderly Patients? A Retrospective Cohort Study

BACKGROUND

Increased risk of bleeding after major orthopedic surgery (MOS) has been widely documented in general population. However, this complication has not been studied in elderly patients. The purpose of this study is to determine whether the risk of major bleeding after MOS is higher in elderly patients, compared with those operated at a younger age.

METHODS

This retrospective cohort study included total hip and total knee arthroplasty patients operated during 5 consecutive years. The main outcome was the occurrence of major bleeding. Patients with other causes of bleeding were excluded. Relative risks (RRs) and confidence intervals (CIs) were calculated, and a multivariate analysis was performed.

RESULTS

A total of 1048 patients were included, 56% of patients were hip arthroplasties. At the time of surgery, 553 (53%) patients were older than 70 years. Patients aged >70 years showed an increased risk of major bleeding (RR: 2.42 [95% CI: 1.54-3.81]). For hip arthroplasty, the RR of bleeding was 2.61 (95%CI: 1.50-4.53) and 2.25 (95% CI: 1.03-4.94) for knee arthroplasty. After multivariate analysis, age was found to be independently associated with higher risk of major bleeding.

CONCLUSION

According to European Medicines Agency criteria, patients aged ≥70 years are at a higher risk of major bleeding after MOS, result of a higher frequency of blood transfusions in this group of patients. Standardized protocols for blood transfusion in these patients are still required.

Rivaroxaban for thromboprophylaxis after total hip or knee arthroplasty: a meta-analysis with trial sequential analysis of randomized controlled trials

Venous thromboembolism (VTE) is the most widespread severe complication after total hip arthroplasty (THA) and total knee arthroplasty (TKA). We conducted this meta-analysis to further validate the benefits and harms of rivaroxaban use for thromboprophylaxis after THA or TKA. We thoroughly searched PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials. Trial sequential analysis (TSA) was applied to test the robustness of our findings and to obtain a more conservative estimation. Of 316 articles screened, nine studies were included. Compared with enoxaparin, rivaroxaban significantly reduced symptomatic VTE (P = 0.0001) and symptomatic deep vein thrombosis (DVT; P = 0.0001) but not symptomatic pulmonary embolism (P = 0.57). Furthermore, rivaroxaban was not associated with an increase in all-cause mortality, clinically relevant non-major bleeding and postoperative wound infection. However, the findings were accompanied by an increase in major bleeding (P = 0.02). The TSA demonstrated that the cumulative z-curve crossed the traditional boundary but not the trial sequential monitoring boundary and did not reach the required information size for major bleeding. Rivaroxaban was more beneficial than enoxaparin for preventing symptomatic DVT but increased the risk of major bleeding. According to the TSA results, more evidence is needed to verify the risk of major bleeding with rivaroxaban.

Venous thromboembolism: identifying patients at risk and establishing prophylaxis

Venous thromboembolism (VTE) is a major cause of morbidity and mortality and is associated with substantial healthcare costs. Identification of patients at risk of developing VTE enables appropriate thromboprophylaxis to be implemented. Although no predisposing risk factors can be identified in many patients in whom VTE develops, most have at least one underlying risk factor which can be categorized according to whether it confers low, moderate, or high risk. Clinical trials have demonstrated the effectiveness of thromboprophylaxis, both non-pharmacological and pharmacological, in a host of medical settings and there is sufficient evidence to support routine prophylaxis in many groups of patients. The implementation of decision making tools based on risk factor assessment improves the prescription of appropriate VTE prophylaxis. Nonetheless, thromboprophylaxis is often inadequate, with haphazard risk assessment and application of guidelines, leading to easily preventable instances of VTE. The most commonly used agents for pharmacological thromboprophylaxis of VTE are low dose unfractionated heparin; a low molecular weight heparin such as dalteparin, enoxaparin or tinzaparin; fondaparinux; warfarin; or aspirin. However, these have a number of drawbacks, principally the need for parenteral administration (with heparins) and frequent coagulation monitoring (with warfarin). The optimal anticoagulant would be orally administered, with a wide therapeutic window, rapid onset of action, predictable pharmacodynamics and pharmacokinetics, minimal interactions with food and other drugs, an ability to inhibit free and clot-bound coagulation factors, low, non-specific binding, and no requirement for routine coagulation monitoring or dose adjustment. A number of novel, single-target oral anticoagulants have been developed that appear to fulfill many of these requirements. This narrative review discusses the use of guidelines and risk assessment tools to identify patients at risk of VTE; it provides an overview of appropriate prophylaxis strategies in these patients with a summary of clinical trial results with novel oral anticoagulants.

New oral anticoagulants in severe trauma patients: enemy at the gates?

The high incidence of trauma, especially in elderly people anticoagulated with new oral anticoagulants (NOAs), has become a major challenge, particularly in critical situations with life-threatening bleeding. Under these circumstances, urgent NOA reversion becomes mandatory. Prothrombin complex has become a frequent indication in critical situations in which rapid reversal of anticoagulation is needed and where the use of fresh frozen plasma is limited. This study offers our point of view regarding the usefulness of NOAs, not only in the prevention of cardioembolic events but also as regards their emergent reversion in cases of severe bleeding associated to trauma.

Rivaroxaban: an oral factor Xa inhibitor

BACKGROUND

Currently available anticoagulants utilized for venous thromboembolism (VTE) treatment and prevention and stroke prevention in patients with atrial fibrillation (AF) have proven effectiveness but are not optimally utilized because of barriers such as the need for subcutaneous administration and requisite routine laboratory monitoring. Rivaroxaban, a novel oral Xa inhibitor, is an alternative to standard therapies utilized for VTE prevention after elective orthopedic surgery, primary and secondary stroke prevention in nonvalvular AF, VTE treatment after an acute VTE event, and secondary prevention after the acute coronary syndromes (ACS).

OBJECTIVE

This article reviews the pharmacology, efficacy, and tolerability of rivaroxaban for VTE prophylaxis in post-orthopedic surgery and medically ill patients, stroke prevention in nonvalvular AF, adjunctive therapy in patients with ACS, and VTE treatment.

METHODS

International Pharmaceutical Abstracts and EMBASE were searched for English-only clinical trials and reviews published between 1970 and March 15, 2012. PubMed was searched for articles published between 1970 and June 30, 2012. Additional trials and reviews were identified from the citations of published articles.

RESULTS

Eighty-nine publications were identified: 10 clinical trials and 1 meta-analysis were used to obtain efficacy and tolerability data, and 1 analysis of pooled data from the clinical trials was included; 17 pharmacokinetic, pharmacodynamic, and drug-drug interaction studies were included; and 5 cost-analyses were reviewed. These data showed rivaroxaban to be noninferior to enoxaparin for thromboprophylaxis of VTE after total knee and total hip replacement surgery. It was also shown to be noninferior to vitamin K antagonist therapy for primary and recurrent stroke prevention in nonvalvular AF as well as for the treatment of VTE after an acute deep vein thrombosis or pulmonary embolism. It also showed benefit in lowering the risk for major adverse cardiovascular events after ACS. Differences in major bleeding rates were not statistically significant between rivaroxaban and comparators across the various studies, with the exception of ACS, in which there were higher rates of non-coronary artery bypass graft surgery related bleeding and intracranial hemorrhage.

CONCLUSIONS

Based on the findings of the studies reported in this review, rivaroxaban is an effective option for the prevention of VTE after orthopedic surgery, stroke prevention for nonvalvular AF, and treatment of VTE. At this time, rivaroxaban cannot be recommended for secondary risk reduction after ACS because of the increased bleeding risk.

New oral anticoagulants increase risk for gastrointestinal bleeding: a systematic review and meta-analysis

BACKGROUND & AIMS

A new generation of oral anticoagulants (nOAC), which includes thrombin and factor Xa inhibitors, has been shown to be effective, but little is known about whether these drugs increase patients' risk for gastrointestinal bleeding (GIB). Patients who require OAC therapy frequently have significant comorbidities and may also take aspirin and/or thienopyridines. We performed a systematic review and meta-analysis of the risk of GIB and clinically relevant bleeding in patients taking nOAC.

METHODS

We queried MEDLINE, EMbase, and the Cochrane library (through July 2012) without language restrictions. We analyzed data from 43 randomized controlled trials (151,578 patients) that compared nOAC (regardless of indication) with standard care for risk of bleeding (19 trials on GIB). Odds ratios (ORs) were estimated using a random-effects model. Heterogeneity was assessed with the Cochran Q test and the Higgins I(2) test.

RESULTS

The overall OR for GIB among patients taking nOAC was 1.45 (95% confidence interval [CI], 1.07-1.97), but there was substantial heterogeneity among studies (I2, 61%). Subgroup analyses showed that the OR for atrial fibrillation was 1.21 (95% CI, 0.91-1.61), for thromboprophylaxis after orthopedic surgery the OR was 0.78 (95% CI, 0.31-1.96), for treatment of venous thrombosis the OR was 1.59 (95% CI, 1.03-2.44), and for acute coronary syndrome the OR was 5.21 (95% CI, 2.58-10.53). Among the drugs studied, the OR for apixaban was 1.23 (95% CI, 0.56-2.73), the OR for dabigatran was 1.58 (95% CI, 1.29-1.93), the OR for edoxaban was 0.31 (95% CI, 0.01-7.69), and the OR for rivaroxaban was 1.48 (95% CI, 1.21-1.82). The overall OR for clinically relevant bleeding in patients taking nOAC was 1.16 (95% CI, 1.00-1.34), with similar trends among subgroups.

CONCLUSIONS

Studies on treatment of venous thrombosis or acute coronary syndrome have shown that patients treated with nOAC have an increased risk of GIB, compared with those who receive standard care. Better reporting of GIB events in future trials could allow stratification of patients for therapy with gastroprotective agents.

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

BACKGROUND

In the past 10 years, new anticoagulants (NACs) have been studied for venous thromboembolism (VTE) prophylaxis.

OBJECTIVE

To evaluate the risk/benefit profile of NACs versus enoxaparin for VTE prophylaxis in major orthopedic surgery.

METHODS

A systematic review of double-blind randomized phase III studies was performed. The search strategy was run from 2000 to 2011 in the main medical electronic databases in any language. Independent extraction of articles was performed by 2 authors using predefined data fields, including study quality indicators.

RESULTS

Fifteen published clinical trials evaluating fondaparinux, rivaroxaban, dabigatran, and apixaban were included. Primary efficacy (any deep vein thrombosis [DVT], nonfatal pulmonary embolism, or all-cause mortality) favored fondaparinux (relative risk [RR] 0.50; 95% CI, 0.39, 0.63) and rivaroxaban (RR, 0.50; 95% CI, 0.34, 0.73) over enoxaparin, although significant heterogeneity was observed in both series. The primary efficacy of dabigatran at 220 mg, apixaban, and bemiparin were similar, with RRs of 1.02 (95% CI, 0.86, 1.20), 0.63 (95% CI, 0.39, 1.01), and 0.87 (95% CI, 0.65, 1.17), respectively. The primary efficacy of dabigatran at 150 mg (RR, 1.20; 95% CI, 1.03, 1.41), was inferior to enoxaparin. The incidence of proximal DVT favored apixaban (RR, 0.45; 95% CI, 0.27, 0.75) only. Rivaroxaban (RR, 0.45; 95% CI, 0.27, 0,77) and apixaban (RR, 0.38; 95% CI, 0.16, 0.90) produced significantly lower frequencies of symptomatic DVT. The incidence of major VTE favored rivaroxaban (RR, 0.44; 95% CI, 0.25, 0.81), only. Bleeding risk was similar for all NACs, except fondaparinux (RR, 1.27; 95% CI, 1.04, 1.55), which exhibited a significantly higher any-bleeding risk compared with enoxaparin, and apixaban (RR, 0.88; 95% CI, 0.79, 0.99), which was associated with a reduced risk of any bleeding. Alanine amino transferase was significantly lower with 220 mg of dabigatran, (RR, 0.67; 95% CI, 0.79, 0.99) than with enoxaparin.

CONCLUSIONS

NACs can be considered alternatives to conventional thromboprophylaxis regimens in patients undergoing elective major orthopedic surgery, depending on clinical characteristics and cost-effectiveness. The knowledge of some differences concerning efficacy or safety profile, pointed out in this systematic review, along with the respective limitations, may be useful in clinical practice.

Prevention of venous thromboembolism in patients admitted to Australian hospitals: summary of National Health and Medical Research Council clinical practice guideline

Each year in Australia, about 1 in 1000 people develop a first episode of venous thromboembolism (VTE), which approximates to about 20,000 cases. More than half of these episodes occur during or soon after a hospital admission, which makes them potentially preventable. This paper summarises recommendations from the National Health and Medical Research Council's 'Clinical Practice Guideline for the Prevention of Venous Thromboembolism in Patients Admitted to Australian Hospitals' and describes the way these recommendations were developed. The guideline has two aims: to provide advice on VTE prevention to Australian clinicians and to support implementation of effective programmes for VTE prevention in Australian hospitals by offering evidence-based recommendations which local hospital guidelines can be based on. Methods for preventing VTE are pharmacological and/or mechanical, and they require appropriate timing, dosing and duration and also need to be accompanied by good clinical care, such as promoting mobility and hydration whilst in hospital. With some procedures or injuries, the risk of VTE is sufficiently high to require that all patients receive an effective form of prophylaxis unless this is contraindicated; in other clinical settings, the need for prophylaxis requires individual assessment. For optimal VTE prevention, all patients admitted to hospital should have early and formal assessments of: (i) their intrinsic VTE risk and the risks related to their medical conditions; (ii) the added VTE risks resulting from surgery or trauma; (iii) bleeding risks that would contraindicate pharmacological prophylaxis; (iv) any contraindications to mechanical prophylaxis, culminating in (v) a decision about prophylaxis (pharmacological and/or mechanical, or none). The most appropriate form of prophylaxis will depend on the type of surgery, medical condition and patient characteristics. Recommendations for various clinical circumstances are provided as summary tables with relevance to orthopaedic surgical procedures, other types of surgery and medical inpatients. In addition, the tables indicate the grades of supporting evidence for the recommendations (these range from Grade A which can be trusted to guide practice, to Grade D where there is more uncertainty; Good Practice Points are consensus-based expert opinions).

Venous thromboembolism: diagnosis and current anticoagulation strategies for deep vein thrombosis and pulmonary embolism

The diagnosis and treatment of venous thromboembolic events represents a significant source of medical spending, both domestically and worldwide. Advances in medical imaging and pharmacology continue to alter and improve established treatment paradigms. In this article, we discuss venous thromboembolism etiology, diagnosis, and rationale for current and future treatment strategies.

Breakthroughs in anticoagulation: advent of the oral direct factor Xa inhibitors

The oral direct factor Xa inhibitors include rivaroxaban and apixaban that recently have been evaluated comprehensively in multiple randomized clinical trials. Based on the efficacy and safety data from these trials, these novel anticoagulants are disseminating throughout clinical practice for thromboprophylaxis in major lower-extremity joint replacement, acute medical illness, atrial fibrillation, and acute coronary syndromes. The advantages of the xabans over vitamin K antagonists include no requirement for routine anticoagulation monitoring as well as a fast and reliable onset of action. The first perioperative limitation of the xabans is the lack of a routine coagulation test for monitoring their anticoagulant effect in scenarios, such as the timing of surgical procedures, the reversal of xaban-related bleeding, and the conduct of regional anesthesia. A second perioperative limitation is the lack of fully validated clinical reversal agents although prothrombin complex concentrate, recombinant factor VIIa, and factor X concentrate are options for xaban reversal in life-threatening bleeding scenarios. Given their clinical efficacy and advantages, further xabans are in clinical development, with edoxaban already in phase III clinical trials. Although the xabans have ushered in a new paradigm for clinical anticoagulation, further clinical trials are indicated to refine their clinical indications even further, such as anticoagulation for patients with mechanical heart valves.

Which design for which question? An exploration toward a translation table for comparative effectiveness research

In this paper, we explore the relative value that different methods offer in answering some stereotypical comparative effectiveness research questions with the goal of informing development of a ‘translation table’ – a selection tool for choosing appropriate methods for specific comparative effectiveness research questions. This paper was written as a parallel effort to Greenfield and Kaplan (also in this volume) to support the endeavor described in the manuscript by Tunis et al. (also in this volume). Originally based on four cases, the current article has been shortened to two cases for the current discussion. These cases represent research priorities proposed to orient the work of the Patient-Centered Outcomes Research Institute, comparative clinical effectiveness and comparative health services.

New anticoagulants - promising and failed developments

New direct and indirect acting factor Xa (FXa) and thrombin inhibitors are being developed to overcome the downsides of the conventional anticoagulants - unfractionated and low molecular weight heparins and vitamin K antagonists. Ximelagatran and idraparinux failed to demonstrate an acceptable safety profile. Rivaroxaban and dabigatran are approved for the post-operative prevention of thromboembolic complications after elective hip or knee replacement surgery; dabigatran is approved for the prevention of embolism in patients with atrial fibrillation in an increasing number of countries. Several novel indirect antithrombin-dependent anticoagulants as well as antithrombin-independent oral direct FXa and thrombin inhibitors are investigated in multiple indications for the prophylaxis and treatment of venous thromboembolism and the prophylaxis of arterial thrombotic disorders. Quality-adjusted life years costs and incremental cost-effectiveness ratios are relatively high at present, but may decrease after approval of more new anticoagulants for additional indications.

Apixaban and rivaroxaban safety after hip and knee arthroplasty: a meta-analysis

Direct experimental safety comparisons of Xa coagulation factor direct inhibitors, apixaban and rivaroxaban, on their approved therapeutic indications have not been identified. Due to recently raised safety concerns, a meta-analysis was carried out pooling data from studies identified on a Medline and Cochrane Library search in order to better evaluate the safety profile of both drugs. Abstracts from scientific meetings were also searched from 2003 to 2011. Primary and secondary outcome measures were major bleeding and total bleeding, respectively. Relative risks (RRs) were estimated using random effects models and statistical heterogeneity was estimated with I(2) statistics. Of the 160 screened publications, 12 clinical trials were included in which enoxaparin was the active control. For knee arthroplasty, apixaban was associated with significantly fewer major bleeding events (6496 patients, RR 0.56, 95% confidence interval [CI] 0.32-0.96) and fewer total bleeding events (6496 patients, RR 0.81, 95% CI 0.67-0.97). There were no significant differences in the incidence of major bleeding events (5699 patients, RR 1.40, 95% CI 0.56-3.52) or in the incidence of total bleeding events for rivaroxaban (5699 patients, RR 1.09, 95% CI 0.91-1.30). No differences were found when thromboprophylaxis after hip replacement was the case. Apixaban seems to be associated with a lower risk of the incidence of hemorrhagic events after total knee arthroplasty. For hip arthroplasty, no differences were found between the studied drugs.

Rivaroxaban

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New anticoagulants: moving on from scientific results to clinical implementation

Vitamin K antagonists (VKA) are the only registered oral anticoagulants for the treatment of venous thromboembolism (VTE). VKA have an unpredictable and highly variable effect on coagulation, with a high risk of under- and over-treatment. Novel anticoagulants, such as dabigatran and rivaroxaban, could be a very welcome replacement for VKA, as they show a predictable anticoagulant effect. Results of several phase II and III studies have shown the efficacy and safety of dabigatran and rivaroxaban in the prophylaxis and treatment of VTE, and for the prevention of stroke in atrial fibrillation. It remains to be shown whether these new anticoagulants have the same safety profile in daily clinical practice, where more vulnerable patients will be treated. Lack of information on the proper monitoring method or antidote in case of bleeding may also hinder the translation from science to clinical practice.

Reversal of rivaroxaban and dabigatran by prothrombin complex concentrate: a randomized, placebo-controlled, crossover study in healthy subjects

BACKGROUND

Rivaroxaban and dabigatran are new oral anticoagulants that specifically inhibit factor Xa and thrombin, respectively. Clinical studies on the prevention and treatment of venous and arterial thromboembolism show promising results. A major disadvantage of these anticoagulants is the absence of an antidote in case of serious bleeding or when an emergency intervention needs immediate correction of coagulation. This study evaluated the potential of prothrombin complex concentrate (PCC) to reverse the anticoagulant effect of these drugs.

METHODS AND RESULTS

In a randomized, double-blind, placebo-controlled study, 12 healthy male volunteers received rivaroxaban 20 mg twice daily (n=6) or dabigatran 150 mg twice daily (n=6) for 2½ days, followed by either a single bolus of 50 IU/kg PCC (Cofact) or a similar volume of saline. After a washout period, this procedure was repeated with the other anticoagulant treatment. Rivaroxaban induced a significant prolongation of the prothrombin time (15.8±1.3 versus 12.3±0.7 seconds at baseline; P<0.001) that was immediately and completely reversed by PCC (12.8±1.0; P<0.001). The endogenous thrombin potential was inhibited by rivaroxaban (51±22%; baseline, 92±22%; P=0.002) and normalized with PCC (114±26%; P<0.001), whereas saline had no effect. Dabigatran increased the activated partial thromboplastin time, ecarin clotting time (ECT), and thrombin time. Administration of PCC did not restore these coagulation tests.

CONCLUSION

Prothrombin complex concentrate immediately and completely reverses the anticoagulant effect of rivaroxaban in healthy subjects but has no influence on the anticoagulant action of dabigatran at the PCC dose used in this study. Clinical Trial Registration- URL: http://www.trialregister.nl. Unique identifier: NTR2272.

How to prevent, treat, and overcome current clinical challenges of VTE

Venous thromboembolism (VTE) is most commonly initially treated with low molecular weight heparin (LMWH), fondaparinux, or unfractionated heparin, in combination with vitamin-K antagonists (VKA) for long-term treatment. VKA have some drawbacks, however, which has led to the development of new anticoagulants. Most of these new drugs can be administered orally, and have been investigated in several phase III clinical trials. The benefits of these anticoagulants include their stable therapeutic effect, reduced interactions with other medication and food, and, therefore, the reduced need for regular monitoring. The duration of anticoagulant treatment for VTE is usually 3-12 months, but depends on the balance between the risks of recurrent thrombosis, major bleeding, and the patient's preference. Clinical decision rules to assess the risk of recurrence to tailor the duration of anticoagulant treatment are being investigated. The beneficial aspects of novel anticoagulants may prolong the duration of treatment. VTE treatment should be adjusted in special patient groups, such as in cases of malignancy, renal failure, pregnancy, or obesity. In this review, the current and future aspects of the treatment of VTE are explored.

Blood coagulation factor Xa as an emerging drug target

INTRODUCTION

Factor (F)Xa is well-known as an important player in the coagulation cascade responsible for thrombin generation. More recently, FXa emerged as an essential player in cell biology via activation of protease-activated receptors (PAR)-1 and -2. This pleiotropic role of FXa forms the basis for its potential contribution to the pathogenesis of several diseases.

AREAS COVERED

The role of FXa in pathophysiology is reviewed with special emphasis on its signal transduction properties. To this end, we first discuss the important role of FXa in the coagulation cascade, we continue with recent data on FXa induced signaling in pathophysiology with special emphasis on tissue remodeling and fibrosis and discuss the potential of FXa as an emerging drug target.

EXPERT OPINION

FXa is more than a passive intermediate in the coagulation cascade and FXa may in fact orchestrate fundamental processes during pathophysiology. Targeting FXa may be an exciting new therapeutic strategy in the treatment of (fibro)proliferative diseases for which current treatment options are limited.