Apixaban or enoxaparin for thromboprophylaxis after knee replacement

Comparison of Postoperative Bleeding in Total Hip and Knee Arthroplasty Patients Receiving Rivaroxaban, Enoxaparin, or Aspirin for Thromboprophylaxis

BACKGROUND

Guidelines recommend the use of multiple pharmacologic agents and/or mechanical compressive devices for prevention of venous thromboembolism, but preference for any specific agent is no longer given in regard to safety or efficacy.

OBJECTIVE

To compare postoperative bleeding rates in patients receiving enoxaparin, rivaroxaban, or aspirin for thromboprophylaxis after undergoing elective total hip arthroplasty or total knee arthroplasty.

METHODS

This retrospective cohort analysis evaluated patients who received thromboprophylaxis with either enoxaparin, rivaroxaban, or aspirin. All data were collected from the electronic medical record. The primary outcome was any postoperative bleeding.

RESULTS

A total of 1244 patients were included with 366 in the aspirin, 438 in the enoxaparin, and 440 in the rivaroxaban arms. Those who received aspirin or enoxaparin were less likely to experience any bleeding compared to those patients who received rivaroxaban ( P < .05). There was also a lower rate of major bleeding in these groups, but the differences were not significant.

CONCLUSIONS

Aspirin and enoxaparin conferred similar bleeding risks, and both exhibited less bleeding than patients who received rivaroxaban.

Population Pharmacokinetics of Apixaban in Subjects With Nonvalvular Atrial Fibrillation

This analysis describes the population pharmacokinetics (PPK) of apixaban in nonvalvular atrial fibrillation (NVAF) subjects, and quantifies the impact of intrinsic and extrinsic factors on exposure. The PPK model was developed using data from phase I-III studies. Apixaban exposure was characterized by a two-compartment PPK model with first-order absorption and elimination. Predictive covariates on apparent clearance included age, sex, Asian race, renal function, and concomitant strong/moderate cytochrome P450 (CYP)3A4/P-glycoprotein (P-gp) inhibitors. Individual covariate effects generally resulted in < 25% change in apixaban exposure vs. the reference NVAF subject (non-Asian, male, aged 65 years, weighing 70 kg without concomitant CYP3A4/P-gp inhibitors), except for severe renal impairment, which resulted in 55% higher exposure than the reference subject. The dose-reduction algorithm resulted in a ~27% lower median exposure, with a large overlap between the 2.5-mg and 5-mg groups. The impact of Asian race on apixaban exposure was < 15% and not considered clinically significant.

Direct Oral Anticoagulants vs Low-Molecular-Weight Heparin for Thromboprophylaxis in Nonoperative Pelvic Fractures

BACKGROUND

Patients with pelvic fractures are prone to venous thromboembolic (VTE) complications. Recent literature shows superiority of direct oral anticoagulants (DOACs) over low-molecular-weight heparin (LMWH) for thromboprophylaxis in patients undergoing orthopaedic operations. The aim of our study was to compare in-hospital outcomes for DOACs vs LMWH in patients with nonoperative pelvic fractures.

STUDY DESIGN

We performed a 2-year (2015 to 2016) analysis of the American College of Surgeons-Trauma Quality Improvement Program (ACS-TQIP) database. We included all adult patients with isolated blunt pelvic fractures who were managed nonoperatively and received thromboprophylaxis with either LMWH or DOACs (Factor-Xa inhibitor or direct thrombin inhibitor). Patients were divided into 2 groups based on receipt of DOACs vs LMWH and were propensity-score-matched in a 1:2 ratio to control for possible confounding factors. Primary outcomes were deep venous thrombosis (DVT) and/or pulmonary embolism (PE). Secondary outcomes were pRBC transfusions, intervention for hemorrhage control, and in-hospital mortality after initiation of thromboprophylaxis.

RESULTS

We identified 20,692 patients with pelvic fractures. There were 7,312 patients with isolated pelvic fractures included, 852 of whom were matched (DOACs: 284; LMWH: 568). Mean age was 43.2 ± 15 years, median Injury Severity Score was 14 (range 10 to 18). Matched groups were similar in demographics, vital signs, injury parameters, and timing of initiation of thromboprophylaxis. Overall, 5.2% of patients had DVT, 1.4% PE, and 1.3% died. Patients who received DOACs were less likely to develop DVT (1.8% vs 6.9%, p < 0.01) compared with LMWH. There was no difference in PE (p = 0.85) or in-hospital mortality (p = 0.79) between the 2 groups. Similarly, there was no difference in post-prophylaxis blood transfusion, and post-prophylaxis intervention for hemorrhage control.

CONCLUSIONS

In patients with nonoperative pelvic fractures, DOACs were associated with a reduced rate of DVT vs LMWH without increasing the risk of bleeding complications. No association was found between the type of thromboprophylactic agent and rates of PE or in-hospital mortality.

Meta-Analysis Comparing the Efficacy, Safety, and Cost-Benefit of Direct Acting Oral Anticoagulants Versus Enoxaparin Thromboprophylaxis to Prevent Venous Thromboembolism Among Hospitalized Patients

Venous thromboembolism (VTE) is a potentially fatal complication of hospitalization. Thromboprophylaxis using subcutaneous low molecular weight heparin (LMWH) can result in local irritation, pain, and ecchymoses, leading to nonadherence. Direct acting oral anticoagulants (DOACs) are an alternative, but their efficacy and safety for short-term inpatient-only use versus LMWH, in medically hospitalized patients, has not been rigorously assessed. We performed a systematic review with meta-analyses and exploratory cost effectiveness analysis of Phase III randomized controlled trials comparing DOACs to LMWH for VTE prophylaxis to determine the risk and benefit of each. The primary efficacy end point (composite of total VTE and any-cause mortality) occurred in 1,321 of 10,978 (11.4%) of patients receiving DOAC prophylaxis and 1,084 of 10,600 (10.2%) with LMWH (odds ratio [OR] 0.84; 95% confidence interval [CI] 0.63 to 1.13). The primary safety end point (composite of major bleeding and clinically relevant bleeding) occurred in 519 of 16,131 (3.2%) of patients receiving DOACs and 381 of 14,616 (2.6%) with LMWH (OR 1.12; 95%CI 0.83 to 1.53). Subgroup analyses for efficacy (n = 9,233) and safety (n = 12,584) was conducted on patients randomized to Apixaban or LMWH. The primary efficacy end point occurred in 294 of 4618 (6.4%) patients on Apixaban and 383 of 4615 (8.3%) on Enoxaparin (OR 0.82; 95% CI 0.55 to 1.24). Major and clinically relevant bleeding occurred in 157 of 6278 (2.50%) and 185 of 6,306 (2.9%), respectively (OR 0.86; 95% CI 0.58 to 1.26). Exploratory cost effectiveness analysis suggested that Apixaban compared with Enoxaparin thromboprophylaxis could result in long-term cost savings. In conclusion, this systematic review of randomized controlled trials and meta-analysis, stratified by type of patients and drug, indicates noninferiority of DOACs in efficacy, safety, and cost for short-term VTE thromboprophylaxis among patients hospitalized for medical illness.

Bleeding in patients receiving non-vitamin K oral anticoagulants: clinical trial evidence

In optimizing anticoagulation therapy, it is essential to balance treatment efficacy with the major adverse effect of anticoagulant treatment, bleeding risk. This narrative review examines the efficacy and safety of the non-vitamin K antagonist oral anticoagulants (NOACs) dabigatran, rivaroxaban, apixaban, and edoxaban compared with standard anticoagulation or placebo. NOAC therapies provide equivalent to superior protection versus standard therapy, with similar or superior safety, and potential benefits in convenience. We will review the phase III evidence for each of the available NOACs in different antithrombotic indications, including atrial fibrillation (in the absence of significant mitral stenosis or mechanical heart valves); prophylaxis of venous thromboembolism (VTE) in patients undergoing orthopedic surgery; and acute and long-term treatment of VTE. Further, we will illustrate scenarios in which the evidence is stronger for a particular agent in the context of the overall positive safety and efficacy profile of NOACs in general. Limitations of the factor Xa inhibitors include the lack of a specific antidote in case of a bleeding emergency (an approved agent is available for reversing the effect of the direct thrombin inhibitor). We discuss the options for mitigating bleeding and describe the ongoing developments towards specific reversal agents. In conclusion, the available data for efficacy and safety, together with reliable pharmacokinetics obviating the need for regular monitoring, indicate that NOACs may offer substantial benefits for patients with nonvalvular atrial fibrillation or VTE.

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.

Pulmonary Embolism While on Aspirin for Venous Thromboembolism Prophylaxis After Total Knee Arthroplasty

A 62-year-old Caucasian man with past medical history significant for coronary artery disease, status post drug eluting stent to the left anterior descending artery 10 years prior, was admitted for elective total right knee arthroplasty. His intraoperative course was uneventful, and he was discharged on hospital day 2 on aspirin 325 mg twice daily for 6 weeks for venous thromboembolism (VTE) prophylaxis. Three weeks later the patient developed chest pain shortly after an approximately 1-hour flight and presented to a local emergency department where computed tomography angiogram showed pulmonary emboli involving segmental and subsegmental pulmonary arteries bilaterally. He was transitioned from aspirin 325 mg twice a day to rivaroxaban 15 mg twice daily for 21 days, with a plan to transition to 20 mg daily to complete a 3-month course. He returned to his primary care physician 6 days after discharge with questions about his current anticoagulation therapy as well as the regimen he was on prior to the pulmonary embolism. Two major organizations, The American Academy of Orthopedic Surgeons and The American College of Chest Physicians, provide recommendations for VTE prophylaxis, but they differ regarding the preferred pharmacologic modality and duration. Although the goal is to provide optimal patient care, lack of guideline consensus may lead to different postoperative recommendations. It is important for clinicians to discuss with their patients the pharmacologic options available for VTE prophylaxis, how organizations differ in their recommendations, and the limitations of these pharmacologic agents.

Pharmacokinetic drug interactions of the non-vitamin K antagonist oral anticoagulants (NOACs)

The use of warfarin, the most commonly prescribed oral anticoagulant, is being questioned by clinicians worldwide due to warfarin several limitations (a limited therapeutic window and significant variability in dose-response among individuals, in addition to a potential for drug-drug interactions). Therefore, the need for non-vitamin K antagonist oral anticoagulants (NOACs) with a rapid onset of antithrombotic effects and a predictable pharmacokinetic (PK) and pharmacodynamic (PD) profile led to the approval of five new drugs: the direct factor Xa (F-Xa) inhibitors rivaroxaban, apixaban, edoxaban and betrixaban (newly approved by FDA) and the direct thrombin (factor-IIa) inhibitor dabigatran etexilate. The advantages of NOACs over warfarin are a fixed-dosage, the absence of the need for drug monitoring for changes in anti-coagulation and fewer clinically significant PK and PD drug-drug interactions. NOACs exposure will likely be increased by the administration of strong P-glycoprotein (P-gp) and cytochrome P450 (CYP) 3A4-inhibitors and may increase the risk of bleeds. On the contrary, P-gp inducers could significantly decrease the NOACs plasma concentration with an associated reduction in their anticoagulant effects. This manuscript gives an overview of NOACs PK profiles and their drug-drug interactions potential. This is meant to be of help to physicians in choosing the best therapeutic approach for their patients.

A systematic review and Bayesian network meta-analysis of risk of intracranial hemorrhage with direct oral anticoagulants

Essentials Risk of intracranial hemorrhage (ICH) may differ between direct oral anticoagulants (DOACs). We compared the risk of ICH between DOACs using network meta-analysis. Dabigatran 110 mg and 150 mg were safer than rivaroxaban on Bayesian analysis. Dabigatran 110 mg ranked as the safest DOAC while rivaroxaban ranked last.

SUMMARY

Background The comparative risk of intracranial hemorrhage (ICH) among direct oral anticoagulants (DOACs) (dabigatran, rivaroxaban, apixaban and edoxaban) remains unclear. Objective To determine the difference in risk of ICH between DOACs Methods Seventeen randomized controlled trials (RCTs) were selected using PubMed/MEDLINE, EMBASE and CENTRAL (Inception, 31 December 2017). Estimates were reported as odds ratio (OR) with 95% credible interval (CR.I) in Bayesian network meta-analysis (NMA), and OR with 95% confidence interval (CI) in traditional meta-analyses. Relative ranking probability of each group was generated based on surface under the cumulative ranking curve (SUCRA). Results In NMA of 116 618 patients from 17 RCTs (apixaban = 19 495 patients, rivaroxaban = 14 157 patients, dabigatran = 16 074 patients, edoxaban = 11 652 patients, and comparator = 55 315 patients), all DOACs were safer than warfarin for risk of ICH. Dabigatran 110 mg ranked as the safest drug (SUCRA, 0.85) and reduced the risk of ICH by 56% compared to rivaroxaban (OR, 0.44; 95% Cr.I, 0.22-0.82). Pairwise meta-analysis validated these findings, showing that DOACs were safer than warfarin (OR, 0.46; 95% CI, 0.35-0.59). Subgroup analysis showed that the benefit was present when DOACs were used in non-valvular atrial fibrillation (NVAF) (OR, 0.51; 95% CI, 0.38-0.68) or venous thromboembolism (VTE) (OR, 0.32; 95% CI, 0.18-0.58). Conclusion Dabigatran 110 mg may be the safest choice among any anticoagulant regarding risk of ICH. Both dabigatran 110 mg and 150 mg were safer than rivaroxaban.

Reversal of apixaban induced alterations in haemostasis by different coagulation factor concentrates in patients after hip or knee replacement surgery

BACKGROUND

Apixaban is a direct oral anticoagulant (DOAC) with a specific inhibition of activated factor X (FXa). In case of bleeding or need of urgent surgery a direct antidote is not yet available. Off-label application of non-specific haemostatic agents, such as prothrombin complex concentrate (PCC) and recombinant FVIIa (rFVIIa), has been reported to reverse the effects of apixaban in in vitro and animal studies. The aim of this study is to measure the reversal potential of PCC and rFVIIa in patients with prophylactic apixaban concentrations.

MATERIAL AND METHODS

Whole blood from patients under prophylactic therapy with apixaban was spiked with two doses of PCC or rFVIIa. Thromboelastometry (ROTEM^®), prothrombin time (PT), and activated partial prothrombin time (aPTT) were performed.

RESULTS

Prolongations in PT and aPTT were corrected by the different concentrates with variable efficacies (PCC<rFVIIa) for all time points after medication. Compared with baseline, the reversal effects ranged from partial correction (PCC) to overcorrection of the CT-ExTEM, PT and aPTT by rFVIIa.

DISCUSSION

PCC partially reverses the effect of apixaban as measured by point-of-care coagulation testing and standard coagulation tests. Only rFVIIa reliably reverses apixaban anticoagulation.

Thromboembolism prophylaxis in orthopaedics: an update

Venous thromboembolism (VTE) is a serious complication during and after hospitalization, yet is a preventable cause of in-hospital death.

Without VTE prophylaxis, the overall VTE incidence in medical and general surgery hospitalized patients is in the range of 10% to 40%, while it ranges up to 40% to 60% in major orthopaedic surgery. With routine VTE prophylaxis, fatal pulmonary embolism is uncommon in orthopaedic patients and the rates of symptomatic VTE within three months are in the range of 1.3% to 10%.

VTE prophylaxis methods are divided into mechanical and pharmacological. The former include mobilization, graduated compression stockings, intermittent pneumatic compression device and venous foot pumps; the latter include aspirin, unfractionated heparin, low molecular weight heparin (LMWH), adjusted dose vitamin K antagonists, synthetic pentasaccharid factor Xa inhibitor (fondaparinux) and newer oral anticoagulants. LMWH seems to be more efficient overall compared with the other available agents. We remain sceptical about the use of aspirin as a sole method of prophylaxis in total hip and knee replacement and hip fracture surgery, while controversy still exists regarding the use of VTE prophylaxis in knee arthroscopy, lower leg injuries and upper extremity surgery.

Cite this article: EFORT Open Rev 2018;3:136-148. DOI: 10.1302/2058-5241.3.170018

Impact of ABCB1, ABCG2, and CYP3A5 polymorphisms on plasma trough concentrations of apixaban in Japanese patients with atrial fibrillation

OBJECTIVES

During anticoagulant therapy, major bleeding is one of the most severe adverse effects. This study aimed to evaluate the relationships between ABCB1, ABCG2, and CYP3A5 polymorphisms and plasma trough concentrations of apixaban, a direct inhibitor of coagulation factor X.

PATIENTS AND METHODS

A total of 70 plasma concentrations of apixaban from 44 Japanese patients with atrial fibrillation were analyzed. In these analyses, the plasma trough concentration/dose (C/D) ratio of apixaban was used as a pharmacokinetic index and all data were stratified according to the presence of ABCB1 (ABCB1 1236C>T, 2677G>T/A, and 3435C>T), ABCG2 (ABCG2 421C>A), and CYP3A5 (CYP3A5*3) polymorphisms. Influences of various clinical laboratory parameters (age, serum creatinine, estimated glomerular filtration rate, aspartate amino transferase, and alanine amino transferase) on the plasma trough C/D ratio of apixaban were included in analyses.

RESULTS

Although no ABCB1 polymorphisms affected the plasma trough C/D ratio of apixaban, the plasma trough C/D ratio of apixaban was significantly higher in patients with the ABCG2 421A/A genotype than in patients with the ABCG2 421C/C genotype (P<0.01). The plasma trough C/D ratio of apixaban in patients with CYP3A5*1/*3 or *3/*3 genotypes was also significantly higher than that in patients with the CYP3A5*1/*1 genotype (P<0.05). Furthermore, the plasma trough C/D ratio of apixaban decreased with increased estimated glomerular filtration rate.

CONCLUSION

These results indicate that ABCG2 421A/A and CYP3A5*3 genotypes and renal function are considered potential factors affecting trough concentrations of apixaban.

Postoperative bleeding risk of direct oral anticoagulants after oral surgery procedures: a systematic review and meta-analysis

Direct oral anticoagulants (dabigatran, rivaroxaban, apixaban and edoxaban; DOACs) have been introduced to improve safety and superior therapeutic value compared to their predecessors such as warfarin or enoxaparin. The aim of this systematic review and meta-analysis was to assess the postoperative bleeding risk of DOACs during oral surgery procedures. Systematic searches were performed in electronic databases including PubMed, Scopus, Web of Science and Cochrane Library. Thirteen studies were included in the qualitative synthesis: two retrospective case-control studies, five prospective case-control studies, three cross-sectional studies, two case series and a case report; while only six studies were statistically analysed. The risk ratio of postoperative bleeding in DOACs patients was significantly greater than in healthy patients (3.04; 95% confidence interval (CI)=1.31-7.04). This is especially true for rivaroxaban (4.13; 95% CI=1.25-13.69), and less so for dabigatran which presented a risk ratio similar to that of healthy patients (1.00; 95% CI=0.21-4.82). However, further research is required to support these results. Both apixaban and edoxaban were excluded from statistical analysis due to the lack of clinical studies.

Effect of oral factor Xa inhibitor and low-molecular-weight heparin on surgical complications following total hip arthroplasty

This prospective study was conducted to report the effect of oral factor Xa inhibitor and low-molecular-weight heparin (LMWH) on surgical complications following total hip arthroplasty (THA). The patients with an age < 60 years were randomly assigned to three groups (rivaroxaban, enoxaparin, and placebo) and the patients with an age ≥ 60 years were assigned to two groups (rivaroxaban and enoxaparin). All drug regimens started at 12 hours postoperatively and continued for two weeks after surgery. Primary measure outcome was major surgical wound complications defined as haematoma requiring any intervention, superficial wound infection, deep periprosthetic infection, and increased wound bleeding. Secondary measured outcome included minor surgical complications (swelling, drainage, erythema, and oozing), organ bleeding, and venous thromboembolic (VTE) events. A total of 184 patients aged < 60 years and 167 patients aged ≥ 60 years were included as the analysis population per group. Up to 14 days after surgery, the overall incidence of major surgical complications associated with thromboprophylaxis was 6.5 % (58/886). There were no significant differences in the rate of major surgical complications among all the three groups of the patients aged < 60 years and between two groups of the patients aged ≥ 60 years. For the patients aged < 60 years, wound oozing continued significantly longer in the pharmacological group than in the placebo group, but wound infection did not occur in any case. The VTE events were similar in all the groups.

Peri-Procedural Management of Oral Anticoagulants in the DOAC Era

Peri-procedural management of oral anticoagulants can be complex and confusing for many providers. It involves a careful balance of a patient's thromboembolic risk and bleeding risk. For every patient chronically taking an oral anticoagulant who will be undergoing an elective procedure, a four step approach may be considered when creating a plan for the oral anticoagulant. (1) Does the oral anticoagulant need to stop for the procedure? (2) If yes, when should the oral anticoagulant be stopped pre-procedure? (3) Does the patient require a "bridging" parenteral anticoagulant? (4) When should anticoagulation be re-started post procedure? Based on the unique features of warfarin versus the direct oral anticoagulants (DOAC), a unique, personalized plan should be developed and tailored to the individual patient. Anticoagulant specialists, such as anticoagulation clinic pharmacists, may help facilitate this process.

Oral anticoagulants for primary prevention, treatment and secondary prevention of venous thromboembolic disease, and for prevention of stroke in atrial fibrillation: systematic review, network meta-analysis and cost-effectiveness analysis

BACKGROUND

Warfarin is effective for stroke prevention in atrial fibrillation (AF), but anticoagulation is underused in clinical care. The risk of venous thromboembolic disease during hospitalisation can be reduced by low-molecular-weight heparin (LMWH): warfarin is the most frequently prescribed anticoagulant for treatment and secondary prevention of venous thromboembolism (VTE). Warfarin-related bleeding is a major reason for hospitalisation for adverse drug effects. Warfarin is cheap but therapeutic monitoring increases treatment costs. Novel oral anticoagulants (NOACs) have more rapid onset and offset of action than warfarin, and more predictable dosing requirements.

OBJECTIVE

To determine the best oral anticoagulant/s for prevention of stroke in AF and for primary prevention, treatment and secondary prevention of VTE.

DESIGN

Four systematic reviews, network meta-analyses (NMAs) and cost-effectiveness analyses (CEAs) of randomised controlled trials.

SETTING

Hospital (VTE primary prevention and acute treatment) and primary care/anticoagulation clinics (AF and VTE secondary prevention).

PARTICIPANTS

Patients eligible for anticoagulation with warfarin (stroke prevention in AF, acute treatment or secondary prevention of VTE) or LMWH (primary prevention of VTE).

INTERVENTIONS

NOACs, warfarin and LMWH, together with other interventions (antiplatelet therapy, placebo) evaluated in the evidence network.

MAIN OUTCOME MEASURES

Efficacy Stroke, symptomatic VTE, symptomatic deep-vein thrombosis and symptomatic pulmonary embolism. Safety Major bleeding, clinically relevant bleeding and intracranial haemorrhage. We also considered myocardial infarction and all-cause mortality and evaluated cost-effectiveness.

DATA SOURCES

MEDLINE and PREMEDLINE In-Process & Other Non-Indexed Citations, EMBASE and The Cochrane Library, reference lists of published NMAs and trial registries. We searched MEDLINE and PREMEDLINE In-Process & Other Non-Indexed Citations, EMBASE and The Cochrane Library. The stroke prevention in AF review search was run on the 12 March 2014 and updated on 15 September 2014, and covered the period 2010 to September 2014. The search for the three reviews in VTE was run on the 19 March 2014, updated on 15 September 2014, and covered the period 2008 to September 2014.

REVIEW METHODS

Two reviewers screened search results, extracted and checked data, and assessed risk of bias. For each outcome we conducted standard meta-analysis and NMA. We evaluated cost-effectiveness using discrete-time Markov models.

RESULTS

Apixaban (Eliquis^®, Bristol-Myers Squibb, USA; Pfizer, USA) [5 mg bd (twice daily)] was ranked as among the best interventions for stroke prevention in AF, and had the highest expected net benefit. Edoxaban (Lixiana^®, Daiichi Sankyo, Japan) [60 mg od (once daily)] was ranked second for major bleeding and all-cause mortality. Neither the clinical effectiveness analysis nor the CEA provided strong evidence that NOACs should replace postoperative LMWH in primary prevention of VTE. For acute treatment and secondary prevention of VTE, we found little evidence that NOACs offer an efficacy advantage over warfarin, but the risk of bleeding complications was lower for some NOACs than for warfarin. For a willingness-to-pay threshold of > £5000, apixaban (5 mg bd) had the highest expected net benefit for acute treatment of VTE. Aspirin or no pharmacotherapy were likely to be the most cost-effective interventions for secondary prevention of VTE: our results suggest that it is not cost-effective to prescribe NOACs or warfarin for this indication.

CONCLUSIONS

NOACs have advantages over warfarin in patients with AF, but we found no strong evidence that they should replace warfarin or LMWH in primary prevention, treatment or secondary prevention of VTE.

LIMITATIONS

These relate mainly to shortfalls in the primary data: in particular, there were no head-to-head comparisons between different NOAC drugs.

FUTURE WORK

Calculating the expected value of sample information to clarify whether or not it would be justifiable to fund one or more head-to-head trials.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42013005324, CRD42013005331 and CRD42013005330.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

A Practical Review of the Emerging Direct Anticoagulants, Laboratory Monitoring, and Reversal Agents

Millions of patients in the United States use anticoagulation for a variety of indications, such as the prevention of stroke in those with atrial fibrillation (AF) and the treatment and prevention of venous thrombosis. For over six decades warfarin was the only available oral anticoagulant, but now several DOACs are available and their use has become more prevalent in recent years. In spite of this increased use, many physicians remain reluctant to prescribe DOACs due to concerns about bleeding and reversibility.

Edoxaban Enhances Thromboprophylaxis by Physiotherapy After Total Knee Arthroplasty - The Randomized Controlled ESCORT-TKA Trial

BACKGROUND

The pharmacological advantage of combining physiotherapy with anticoagulants for the prevention of venous thromboembolism (VTE) after total knee arthroplasty (TKA) is not fully known. Herein we investigated the potential benefit of this combination therapy in patients undergoing TKA.

METHODS AND RESULTS

The 38 patients were randomly assigned to a physiotherapy group (n=19) or a physiotherapy plus 30 mg/day edoxaban group (n=19). The occurrence of VTE was evaluated, as were serial changes in parameters measured by the Total Thrombus-formation Analysis System, a novel system for quantitatively analyzing thrombus formation using microchips with thrombogenic surfaces (collagen plus tissue factor, atheroma [AR]-chip). Combination therapy significantly reduced the incidence of VTE after TKA compared with monotherapy (P=0.038). The area under the curve (AUC) of thrombus formation for the AR-chip (AR10-AUC30) was significantly lower in the combination group (P=0.001) on Day 7 after TKA than before TKA, but no significant change was observed with monotherapy (P=0.809). In 13 VTE-positive patients, AR10-AUC30was significantly lower in the combination group (n=3) than in the monotherapy group (n=10) on Day 7 (P=0.045).

CONCLUSIONS

The combination of physiotherapy and edoxaban significantly reduced the incidence of VTE after TKA compared with physiotherapy alone. However, it is possible that VTE occurrence after TKA is not only associated with thrombogenicity, but also rheological factors.

The Role of Intraoperative Intermittent Pneumatic Compression Devices in Venous Thromboembolism Prophylaxis in Total Hip and Total Knee Arthroplasty

Venous thromboembolism (VTE) is a common complication after total hip arthroplasty (THA) and total knee arthroplasty (TKA), occurring in up to 85% of patients who are not treated with prophylaxis. The initiation of VTE development may occur intraoperatively. This study investigated whether this gap in VTE prophylaxis can be addressed by the use of intraoperative intermittent pneumatic compression devices (IPCDs) and if intraoperative IPCDs have a meaningful benefit in preventing symptomatic VTE. The authors defined symptomatic VTE as deep venous thrombosis in either lower extremity or a pulmonary embolism. The authors evaluated the medical records of 3379 patients who underwent THA or TKA at their institution in 2014 and 2015. Effects of various factors, including age, sex, body mass index, and smoking status, were compared between these 2 cohorts. Patients who experienced a symptomatic VTE were also matched by age, sex, and procedure type with randomly selected controls. In the patient sample, 47 patients (1.4%) developed VTE. Forty (1.2%) of these patients underwent TKA, whereas 7 (0.2%) underwent THA. Venous thromboembolism occurred less frequently in patients who received intraoperative IPCDs (0.8%) than in patients who did not receive them (1.5%); however, this difference did not reach statistical significance. Total knee arthroplasty was associated with increased odds of VTE compared with THA, as was female sex. These results did not show a statistically significant benefit to the intraoperative use of IPCDs. Pneumatic compression remains a fast, easy, low-cost, low-risk, intuitive intervention that can supplement the postoperative multimodal approach and is worthy of further study. Intraoperative IPCD use should be considered for patients with a higher risk of VTE. [Orthopedics. 2018; 41(1):e98-e103.].

Direct oral anticoagulants: An update

Vitamin K antagonists were the only choice for chronic oral anticoagulation for more than half a century. Over the past few years, direct oral anticoagulants have emerged, including one direct thrombin inhibitor (dabigatran etexilate) and three factor Xa inhibitors (apixaban, edoxaban and rivaroxaban). In randomised controlled trials comparing direct oral anticoagulants with traditional vitamin K antagonists, the direct oral anticoagulants all showed a favourable benefit-risk balance in their safety and efficacy profile, in prevention of thromboembolic events in patients with atrial fibrillation and in the prevention and treatment of venous thromboembolism and acute coronary syndrome. In 2008, dabigatran was the first direct oral anticoagulant approved by the European Medicine Agency. Subsequently, rivaroxaban, apixaban and edoxaban were also authorised. This article reviews the evidence related to the use of these drugs.

Apixaban

Apixaban is a potent reversible inhibitor of the activated human coagulation factor X. This new oral anticoagulant has favourable pharmacokinetic and pharmocodynamic properties which include a concentration-dependent anticoagulant effect, good oral bioavailability, balanced elimination and excretion, infrequent drug or food interactions, and the lack of liver toxicity. Apixaban has already completed a large part of its phase 3 clinical trial programme. In the ARISTOTLE study, which focused on stroke prevention in atrial fibrillation, apixaban showed a balanced efficacy and safety profile, being superior to warfarin both in the prevention of strokes and in the risk of causing major bleeding. A further trial related to this indication, AVERROES, demonstrated the clear superiority of apixaban compared to aspirin treatment. In the primary prophylaxis of venous thromboembolism after orthopaedic surgery, apixaban successfully completed the ADVANCE study programme and was approved in Europe for patients undergoing elective hip or knee replacement. The results of the AMPLIFY and AMPLIFY- EXT studies will soon show whether the inhibitor is also effective in the treatment and secondary prophylaxis after acute deep vein thrombosis and pulmonary embolism. On the other hand, the use of apixaban in the primary prophylaxis of venous thrombosis in hospitalised medical patients, and its administration on top of antiplatelet therapy to patients who have suffered an acute coronary syndrome, have not received support by the results of ADOPT and APPRAISE-II, respectively. In conclusion, on the basis of the available evidence, apixaban appears to be a valuable therapeutic option for the prevention of venous thrombosis and embolic stroke.

Anticoagulants

Anticoagulants are effective in the prevention and treatment of a variety of arterial and venous thrombotic disorders but are associated with an increased risk of serious bleeding complications. Based on well documented studies of patients using vitamin K antagonists the incidence of major bleeding is 0.5%/year and the incidence of intracranial bleeding is 0.2%/year, however, in real life practice this incidence may be even higher. Risk factors for bleeding are the intensity of anticoagulation, the management strategy to keep the anticoagulant effect in the desired range, and patient characteristics. Recently, a new generation of anticoagulants have been developed and is currently evaluated in clinical trials. Initial results show a similar or superior efficacy over conventional anticoagulant agents with a good safety profile. In case of serious bleeding complications in a patient who uses vitamin K antagonists, this anticoagulant treatment can be quickly reversed by administration of vitamin K or coagulation factor concentrates. For the newer anticoagulants, quick reversal strategies are more cumbersome, although some interventions, including prothrombin complex concentrates, show promising results in initial experimental studies.

Indirect comparison meta-analysis of two enoxaparin regimens in patients undergoing major orthopaedic surgery

Two enoxaparin dosage regimens are used as comparators to evaluate new anticoagulants for thromboprophylaxis in patients undergoing major orthopaedic surgery, but so far no satisfactory direct comparison between them has been published. Our objective was to compare the efficacy and safety of enoxaparin 3,000 anti-Xa IU twice daily and enoxaparin 4,000 anti-Xa IU once daily in this clinical setting by indirect comparison meta-analysis, using Bucher’s method. We selected randomised controlled trials comparing another anticoagulant, placebo (or no treatment) with either enoxaparin regimen for venous thromboembolism prophylaxis after hip or knee replacement or hip fracture surgery, provided that the second regimen was assessed elsewhere versus the same comparator. Two authors independently evaluated study eligibility, extracted the data, and assessed the risk of bias. The primary efficacy outcome was the incidence of venous thomboembolism. The main safety outcome was the incidence of major bleeding. Overall, 44 randomised comparisons in 56,423 patients were selected, 35 being double-blind (54,117 patients). Compared with enoxaparin 4,000 anti-Xa IU once daily, enoxaparin 3,000 anti-Xa IU twice daily was associated with a reduced risk of venous thromboembolism (relative risk [RR]: 0.53, 95% confidence interval [CI]: 0.40 to 0.69), but an increased risk of major bleeding (RR: 2.01, 95% CI: 1.23 to 3.29). In conclusion, when interpreting the benefit-risk ratio of new anticoagulant drugs versus enoxaparin for thromboprophylaxis after major orthopaedic surgery, the apparently greater efficacy but higher bleeding risk of the twice-daily 3,000 anti-Xa IU enoxaparin regimen compared to the once-daily 4,000 anti-Xa IU regimen should be taken into account.

Persistent Pulmonary Embolism Rates Following Total Knee Arthroplasty Even With Prophylactic Anticoagulants

BACKGROUND

Symptomatic pulmonary embolism (PE), a significant and life-threatening complication following total knee arthroplasty (TKA), has been described as a "never event." Despite a number of advancements in care, PE continues to occur following TKA. This study evaluates symptomatic PE rates over time in TKA patients enrolled in multicenter randomized clinical trials assessing the efficacy of venous thromboembolism prophylaxis regimens.

METHODS

The MEDLINE and Cochrane Central Register of Controlled Trials were searched to identify clinical trials assessing prophylactic anticoagulation in patients undergoing TKA between January 1995 and December 2016. A random effect model was used to combine PE rates across studies. The pooled proportion of symptomatic PEs was calculated and heterogeneity was quantified with the I² statistic. A 95% prediction interval was constructed to examine what the expected range in the proportion of symptomatic PEs would be in future studies. Meta-regression was used to explore the effect of time on the rate of symptomatic PEs.

RESULTS

A total of 18 studies representing 27,073 patients were included in the meta-analysis. The symptomatic PE rate was 0.37% (95% confidence interval, 0.24%-0.52%). There was significant heterogeneity across studies, I² = 66%. Between 1996 and 2010, the proportion of PEs did not change in the regression analysis. The 95% prediction interval was 0.0002 to 0.0106, indicating that in similar future studies, the true proportion of symptomatic PEs would range from 0.02% to 1.06%.

CONCLUSION

Over a 14-year period, the symptomatic PE rate after TKA was relatively constant even when patients received potent anticoagulation. These results suggest that some patients may have a genetic predisposition to develop a PE and more effective risk stratification protocols need to be developed to make sure patients receive appropriate anticoagulation.

Thromboprophylaxis with enoxaparin and direct oral anticoagulants in major orthopedic surgery and acutely ill medical patients: a meta-analysis

Subjects undergoing major orthopedic surgery and acutely ill hospitalized medical patients represent a population at medium-high risk for venous thromboembolism (VTE). They are treated with low molecular weight heparin (LMWH) and direct oral anticoagulants [DOACs] for VTE prevention. We conducted a meta-analysis of phase III randomized clinical trials evaluating LMWH enoxaparin versus DOACs for prophylaxis of VTE by combining studies including patients undergoing elective total hip and knee replacement surgery, and acutely ill hospitalized medical subjects. Studies were searched using PubMed, MEDLINE, and EMBASE databases until December 2016. Differences in clinical outcomes for efficacy and safety endpoints between treatment groups were expressed as risk differences with 95% confidence intervals (95% CI), using random effects regression models. Fourteen RCTs were considered (60,467 subjects). Overall mortality, symptomatic deep venous thrombosis, non-fatal pulmonary embolism (PE) major bleeding (MB) and clinically relevant non-major bleeding (CRNMB) are not different between treatment regimens. Treatment with LMWH enoxaparin is associated with a lower risk of fatal PE plus VTE-related death compared therapy with DOACs (RD = 0.040%, 95% CI 0.001-0.080%, p = 0.0434). Subgroup analysis shows an incidence of MB (RD = 0.181%, 95% CI 0.029-0.332%, p = 0.0033) and CRNMB (RD = 0.546%, 95% CI 0.009-1.082%, p = 0.0462) in patients treated with 40 mg OD enoxaparin compared to DOACs. In major orthopedic surgery and acutely ill hospitalized medical patients, DOACs do not offer clear advantages in terms of clinical efficacy compared to enoxaparin. The advantage of the latter in terms of major and CRNMB, when used at a dose of 40 mg, is statistically significant, but small in terms of clinical relevance.

Venous Thromboembolism Prophylaxis in Total Hip Arthroplasty and Total Knee Arthroplasty Patients: From Guidelines to Practice

Venous thromboembolism (VTE) prophylaxis is recommended for all patients undergoing total hip arthroplasty or total knee arthroplasty. The selection of an appropriate prophylaxis regimen represents a balance between efficacy and safety. To help orthopaedic surgeons select an appropriate VTE prophylaxis regimen for their patients, the American Academy of Orthopaedic Surgeons and the American College of Chest Physicians have developed guidelines. These guidelines do not recommend an optimal regimen, however. Rather, an individualized prophylaxis regimen that balances efficacy and safety is recommended for each patient, based on various risk factors. Because of a paucity of data and a lack of adequately powered head-to-head trials, implementing these guidelines can be challenging for the orthopaedic surgeon. Knowledge of the prophylaxis options and the VTE risk factors is paramount for developing an effective VTE prophylaxis algorithm for the surgeon's practice.

Anticoagulation strategies for venous thromboembolism: moving towards a personalised approach

Four non-vitamin K antagonist oral anticoagulants (NOACs) have now been evaluated in clinical trials, providing new therapeutic options for the treatment of venous thromboembolism (VTE). Recent position statements call for a move towards tailored recommendations for the treatment of VTE, to better define in whom and under what conditions a particular anticoagulant may improve clinical outcomes. Here we review the phase III data on NOAC trials for the treatment of VTE, assessing the favourability of agents for particular patient subgroups and aetiologies. Where the data permit, individualised risks of recurrent VTE events and bleeding are presented.

Interpretation of endpoints in a network meta-analysis of new oral anticoagulants following total hip or total knee replacement surgery

New oral anticoagulant (NOAC) regimens [dabigatran 150 mg (D150) and 220 mg (D220), rivaroxaban 10 mg (R20), and apixaban 2.5 mg bid (A5)] were effective and safe compared to enoxaparin for the prevention of venous thromboembolism (VTE) following elective total knee (TKR) or hip replacement (THR) surgery. First a cluster analysis was used to identify homogeneous studies for the trial programs of each NOAC. Second, only studies reporting VTE and VTE-related death, major bleeding, and mortality were included. The odds ratio (OR) and 95% confidence interval (CI) were calculated for each NOAC regimen versus the comparator. Third, these data were used for the indirect comparison between NOACs. Cluster analysis identified duration of treatment (10 ± 5 and 34 ± 5 days) as the only homogeneous parameter across all NOAC programs (p>0.05) except for A5 and VTE over 10 ± 5 days (analysis not performed). The results of the calculated OR and 95% CI of the four NOAC regimens over 10 ± 5 and 34 ± 5 days showed inferiority of D150 and D220 compared to R10 for VTE (p<0.01, p<0.001). Comparisons of major bleeding and mortality were not different for all indirect comparisons. Despite the lack of standard definitions for VTE and bleeding outcomes, cluster analysis seems to be an appropriate tool to identify homogeneity across trial programs and to perform an indirect comparison for NOACs for prevention of VTE following TKR and THR surgery.

Benefit-to-harm ratio of thromboprophylaxis for patients undergoing major orthopaedic surgery

Surgeons consider the benefit-to-harm ratio when making decisions regarding the use of anticoagulant venous thromboembolism (VTE) prophylaxis. We evaluated the benefit-to-harm ratio of the use of newer anticoagulants as thromboprophylaxis in patients undergoing major orthopaedic surgery using the likelihood of being helped or harmed (LHH), and assessed the effects of variation in the definition of major bleeding on the results. A systematic literature search was performed to identify phase II and phase III studies that compared regulatory authority-approved newer anticoagulants to the low-molecularweight heparin enoxaparin in patients undergoing major orthopaedic surgery. Analysis of outcomes data estimated the clinical benefit (number-needed-to-treat [NNT] to prevent one symptomatic VTE) and clinical harm (number-needed-to-harm [NNH] or the NNT to cause one major bleeding event) of therapies. We estimated each trial’s benefitto-harm ratio from NNT and NNH values, and expressed this as LHH = (1/NNT)/(1/NNH) = NNH/NNT. Based on reporting of efficacy and safety outcomes, most studies favoured enoxaparin over fondaparinux, and rivaroxaban over enoxaparin. However, when using the LHH metric, most trials favoured enoxaparin over both fondaparinux and rivaroxaban when they included surgical-site bleeding that did not require reoperation in the definition of major bleeding. The exclusion of bleeding at surgical site which did not require reoperation shifted the benefit-to-harm ratio in favour of the newer agents. Variations in the definitions of major bleeding may change the benefit-to-harm ratio and subsequently affect its interpretation. Clinical trials should attempt to improve the consistency of major bleeding reporting.

Benefit–risk profile of non-vitamin K antagonist oral anticoagulants in the management of venous thromboembolism

The prevention and treatment of venous thromboembolism (VTE) remains a clinical challenge, primarily owing to drawbacks associated with the use of heparins and vitamin K antagonists (VKAs). These and other factors, including a growing elderly population, mean that VTE presents a continuing burden to patients and physicians. Anticoagulant therapy is a fundamental approach for VTE management. Non- VKA oral anticoagulants, including the factor Xa inhibitors apixaban, edoxaban and rivaroxaban, and the thrombin inhibitor dabigatran, have been studied in phase III trials across a spectrum of thromboembolic disorders. These agents offer simplified care, with similar or improved efficacy and safety outcomes compared with heparins and vitamin K antagonists. There are several factors a physician must consider when prescribing an anticoagulant. An important consideration with all anticoagulant use is bleeding risk, especially in high-risk groups such as the elderly or those with renal impairment or cancer. In orthopaedic patients, other risks include a need for surgical revision or blood transfusion, or wound complications. Therefore, the clinical benefits of an anticoagulant should ideally be balanced with any risks associated with the therapy. Quantitative benefit–risk assessments are lacking, and owing to differences in trial design the non-VKA oral anticoagulants cannot be compared directly. Based on trial and “reallife” data, this review will summarise the clinical data for the non-VKA oral anticoagulants in the prevention and treatment of VTE, focusing on the balance between the benefits and risks of anticoagulation with these drugs, and their potential impact on VTE management.

New oral anticoagulants in venous thromboembolism prophylaxis in orthopaedic patients: Are they really better?

Prophylaxis against venous thromboembolism (VTE) is considered standard of care. Appropriate chemoprophylaxis for VTE has been mandated by the United States government agencies and consumer groups. However, controversies exist regarding the most clinically relevant and safe chemoprophylaxis protocols in patients undergoing joint replacement surgery. Thus, this paper reviews the clinical efficacy and safety of newer oral anticoagulants. A literature search was performed for oral anticoagulants in advanced stages of development using PubMed and abstracts from thrombosis meetings. Most clinical trial data have demonstrated equal or superior efficacy in venographic endpoints in comparison to low-molecular-weight heparins (LMWH). However, bleeding complications have been reported to occur with oral anticoagulants as frequently as or more frequently than with LMWH. Other potential complications reported include liver enzyme elevation and cardiac irregularities. It remains to be established whether newer oral anticoagulants will be better alternatives to the current standard-ofcare in real-life medical clinical practice.

The perioperative management of new direct oral anticoagulants: a question without answers

New direct oral anticoagulant agents (DOAC) are currently licensed for thromboprophylaxis after hip and knee arthroplasty and for longterm prevention of thromboembolic events in non-valvular atrial fibrillation as well as treatment and secondary prophylaxis of venous thromboembolism. Some other medical indications are emerging. Thus, anaesthesiologists are increasingly likely to encounter patients on these drugs who need elective or emergency surgery. Due to the lack of experience and data, the management of DOAC in the perioperative period is controversial. In this article, we review available information and recommendations regarding the periprocedural management of the currently most clinically developed DOAC, apixaban, dabigatran, and rivaroxaban. We discuss two trends of managing patients on DOAC for elective surgery. The first is stopping the DOAC 1–5 days before surgery (depending on the drug, patient and bleeding risk) without bridging. The second is stopping the DOAC 5 days preoperatively and bridging with low-molecular-weight heparin. The management of patients on DOAC needing emergency surgery is also reviewed. As no data exist for the use of haemostatic products for the reversal of the anticoagulant effect in these cases, rescue treatment recommendations are proposed.

Mandatory contrast-enhanced venography to detect deep-vein thrombosis (DVT) in studies of DVT prophylaxis: upsides and downsides

The introduction of venography into patient care was a major advance because it was the first accurate method for the diagnosis of DVT. Compression ultrasound has since become the preferred test for patients with suspected DVT because, unlike venography, it is simple, non-invasive and widely available. Venography has facilitated the development and approval of new anticoagulants and remains widely used as an efficacy outcome in trials of venous thromboembolism prevention. Most thrombi detected by screening venography are, however, small and unimportant for patients. In order to calculate the trade-off between an asymptomatic thrombus and a bleed we require an estimate of the number of asymptomatic thrombi that must be prevented to avoid a patient-important thrombus. A credible estimate of this ratio is not available. Therefore when used as a measure of efficacy in trials of thromboprophylaxis, venography has limitations for comparing the relative effects of alternative antithrombotic agents on outcomes important to patients.

Risk of Gastrointestinal Bleeding in Patients Taking Non-Vitamin K Antagonist Oral Anticoagulants: A Systematic Review and Meta-analysis

BACKGROUND & AIMS

Non-vitamin K antagonist oral anticoagulants (NOACs) are convenient and effective in the prevention and treatment of venous thromboembolism and the prevention of stroke in patients with atrial fibrillation. However, these drugs have been associated with an increased risk of gastrointestinal (GI) bleeding. We conducted a systematic review and meta-analysis to determine the risk of GI bleeding in patients receiving these drugs.

METHODS

We searched the EMBASE, Medline, Cochrane, and ISI Web of knowledge databases through January 2016 for randomized trials that compared NOACs with conventional anticoagulants for approved indications. We conducted a meta-analysis, reporting odds ratios (ORs) with 95% confidence intervals (CIs). The primary outcome was major GI bleeding. Secondary outcomes included clinically relevant nonmajor bleeding and upper and lower GI bleeding. We performed a priori subgroup analyses by individual drug.

RESULTS

Our analysis included a total of 43 randomized trials, comprising 166,289 patients. There was no difference between NOACs and conventional anticoagulants in the risk of major bleeding (1.5% vs 1.3%, respectively; OR, 0.98; 95% CI, 0.80-1.21), clinically relevant nonmajor bleeding (0.6% vs 0.6%, respectively; OR, 0.93; 95% CI, 0.64-1.36), upper GI bleeding (1.5% vs 1.6%, respectively; OR, 0.96; 95% CI, 0.77-1.20), or lower GI bleeding (1.0% vs 1.0%, respectively; OR, 0.88; 95% CI, 0.67-1.15). Dabigatran (2.0% vs 1.4%, respectively; OR, 1.27; 95% CI, 1.04-1.55) and rivaroxaban (1.7% vs 1.3%, respectively; OR, 1.40; 95% CI, 1.15-1.70) were associated with increased odds of major GI bleeding compared with conventional anticoagulation, whereas no difference was found for apixaban (0.6% vs 0.7%, respectively; OR, 0.81; 95% CI, 0.64-1.02) or edoxaban (1.9% vs 1.6%, respectively; OR, 0.93; 95% CI, 0.78-1.11). These subgroup findings were not observed in other sensitivity analyses.

CONCLUSIONS

In a systematic review and meta-analysis, we found risk of major GI bleeding to be similar between NOACs and conventional anticoagulation. Dabigatran and rivaroxaban, however, may be associated with increased odds of major GI bleeding. Further high-quality studies are needed to characterize GI bleeding risk among NOACs.

Effects of different anticoagulant drugs on the prevention of complications in patients after arthroplasty: A network meta-analysis

BACKGROUND

After arthroplasty treatment, some complications commonly occur, such as early revision, infection/dislocation, and venous thromboembolism (VTE). This study aims to use a network meta-analysis to compare effects of 9 anticoagulant drugs (edoxaban, dabigatan, apixaban, rivaroxaban, warfarin, heparin, bemiparin, ximelagatran, and enoxaparin) in preventing postoperative complications in arthroplasty patients.

METHODS

After retrieving PubMed, Embase, and Cochrane Library database from the inception to November 2016, randomized controlled trials were enrolled. The integration of direct and indirect evidences was performed to calculate odd ratios and the surface under the cumulative ranking curves. Nineteen eligible randomized controlled trials were included.

RESULTS

The network meta-analysis results showed that compared with warfarin, edoxaban, apixaban, and rivaroxaban had a lower incidence rate in asymptomatic deep venous thrombosis, which indicated that edoxaban, apixaban, and rivaroxaban had better effects on prevention. Similarly, in comparison to enoxaparin, edoxaban and rivaroxaban had better effect; rivaroxaban was better than ximelagatran in preventive effects. Compared with apixaban, edoxaban, dabigatan, rivaroxaban, and enoxaparin had a higher incidence rate in clinically relevant non-major bleeding, which showed that preventive effects were relatively poor. In addition, the results of the surface under the cumulative ranking curves showed that rivaroxaban and bemiparin worked best on symptomatic deep venous thrombosis and pulmonary embolism. In terms of bleeding, apixaban and warfarin had better preventive effects.

CONCLUSION

Our findings suggested that rivaroxaban may work better in terms of symptomatic deep venous thrombosis and pulmonary embolism, whereas apixaban had better preventive effects in bleeding.

Rendering factor Xa zymogen-like as a therapeutic strategy to treat bleeding

PURPOSE OF REVIEW

New therapies are needed to control bleeding in a range of clinical conditions. This review will discuss the biochemical properties of zymogen-like factor Xa, its preclinical assessment in different model systems, and future development prospects.

RECENT FINDINGS

Underlying many procoagulant therapeutic approaches is the rapid generation of thrombin to promote robust clot formation. Clinically tested prohemostatic agents (e.g., factor VIIa) can provide effective hemostasis to mitigate bleeding in hemophilia and other clinical situations. Over the past decade, we explored the possibility of using zymogen-like factor Xa variants to rapidly improve clot formation for the treatment of bleeding conditions. Compared to the wild-type enzyme, these variants adopt an altered, low activity, conformation which enables them to resist plasma protease inhibitors. However, zymogen-like factor Xa variants are conformationally dynamic and ligands such as its cofactor, factor Va, stabilize the molecule rescuing procoagulant activity. At the site of vascular injury, the variants in the presence of factor Va serve as effective prohemostatic agents. Preclinical data support their use to stop bleeding in a variety of clinical settings. Phase 1 studies suggest that zymogen-like factor Xa is safe and well tolerated, and a phase 1b is ongoing to assess safety in patients with intracerebral hemorrhage.

SUMMARY

Zymogen-like factor Xa is a unique prohemostatic agent for the treatment of a range of bleeding conditions.

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.

Comparison of postoperative complications after total hip arthroplasty among patients receiving aspirin, enoxaparin, warfarin, and factor Xa inhibitors

Optimal prophylaxis for prevention of venous thromboembolism (VTE) after total joint arthroplasty (TJA) remains debated. The purpose of this study was to compare postoperative complications in patients receiving different VTE chemoprophylactic regimens. Using a nationwide healthcare database, 72,670 THA patients without a history of VTE were identified. Study cohorts received VTE prophylaxis within 30 days postoperatively. Odds ratios and 95% confidence intervals were used to assess 30-day and 90-day postoperative complications (hematoma, hemorrhage, transfusion, pulmonary embolism (PE), VTE, prosthetic joint infection (PJI), and incision/drainage (I&D)). Of the 72,670 THA patients, 25,966 received single medication VTE prophylaxis; 551 (2.12%) aspirin, 6791 (26.15%) enoxaparin, 12,008 (46.25%) warfarin, 5403 (20.81%) rivaroxaban, 876 (3.37%) fondaparinux and 337 (1.30%) apixaban. 30-day complications included; aspirin: I&D; warfarin: I&D, hematoma, hemorrhage, transfusion, PJI, PE and DVT; apixaban: hematoma and hemorrhage. 90-day complications included; aspirin: I&D; warfarin: I&D, hematoma, hemorrhage, transfusion, PJI, PE and DVT. Warfarin was the only anticoagulant associated with a higher risk for DVT, and the highest risk for 30-day and 90-day complications. Aspirin had the highest risk for I&D. Despite three times increased 30-day risk for bleeding, apixaban was effective in preventing VTE during the high-risk 3-month-period. Enoxaparin had the lowest risk for PE and DVT while rivaroxaban had the lowest risk for PJI, hematoma, I&D, hemorrhage and transfusion.

Neuromuscular electrical stimulation for the prevention of venous thromboembolism

Objective Venous thromboembolism, encompassing deep vein thrombosis and pulmonary embolism, is a significant cause of morbidity and mortality, affecting one in 1000 adults per year. Neuromuscular electrical stimulation is the transcutaneous application of electrical impulses to elicit muscle contraction, preventing venous stasis. This review aims to investigate the evidence underlying the use of neuromuscular electrical stimulation in thromboprophylaxis. Methods The Medline and Embase databases were systematically searched, adhering to PRISMA guidelines, for articles relating to electrical stimulation and thromboprophylaxis. Articles were screened according to a priori inclusion and exclusion criteria. Results The search strategy identified 10 randomised controlled trials, which were used in three separate meta-analyses: five trials compared neuromuscular electrical stimulation to control, favouring neuromuscular electrical stimulation (odds ratio of deep vein thrombosis 0.29, 95% confidence interval 0.13-0.65; P = .003); three trials compared neuromuscular electrical stimulation to heparin, favouring heparin (odds ratio of deep vein thrombosis 2.00, 95% confidence interval 1.13-3.52; P = .02); three trials compared neuromuscular electrical stimulation as an adjunct to heparin versus heparin only, demonstrating no significant difference (odds ratio of deep vein thrombosis 0.33, 95% confidence interval 0.10-1.14; P = .08). Conclusion Neuromuscular electrical stimulation significantly reduces the risk of deep vein thrombosis compared to no prophylaxis. It is inferior to heparin in preventing deep vein thrombosis and there is no evidence for its use as an adjunct to heparin.

Apixaban pharmacodynamic activity in umbilical cord, paediatric, and adult plasma

The objective was to characterise apixaban pharmacodynamic (PD) activity in umbilical cord (UC), paediatric, and adult plasma. Plasma was obtained from blood samples from six UC donors, 70 paediatric (neonates [birth-≤1 month], infants [>1-≤6 months], toddlers [>6 months-≤2 years], young children [>2-≤6 years], children [>6-≤12 years], adolescents [>12-≤18 years]), and six adult (19-45 years) subjects. Plasma spiked with apixaban 0 (baseline), 30, or 110 ng/ml was analysed for anti-factor Xa activity, factor X levels, prothrombin time (PT), and modified PT (mPT). Apixaban had similar concentration-related effects on anti-factor Xa activity across groups (30 ng/ml: 0.223-0.295 IU/ml; 110 ng/ml: 1.212-1.474 IU/ml). Endogenous baseline factor X levels were 43 %-68 % lower in plasma from UC and subjects ≤6 months versus adults. Factor Xa inhibition (percentage change from baseline in apparent factor X levels) was similar for both apixaban concentrations across groups, except UC, neonate, and infant groups, which showed greater inhibition vs adults for apixaban 110 ng/ml. Baseline PT and mPT were similar across groups. Apixaban had no effect on PT at the concentrations tested. Apixaban 110 ng/ml prolonged mPT similarly across groups (44.4-53.2 s to 64.5-70.0 s); no prolongation was found with apixaban 30 ng/ml. Apixaban demonstrated consistent concentration-related effects on other PD endpoints in plasma samples from all age groups, except factor Xa inhibition.

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.

Management of Direct-Acting Oral Anticoagulants Surrounding Dental Procedures With Low-to-Moderate Risk of Bleeding

The purpose of this article is to review the available evidence regarding how to safely manage direct-acting oral anticoagulant (DOAC) therapy in patients requiring dental procedures with low-to-moderate risk of bleeding. A literature search was performed using MEDLINE and PubMed. Each author performed an independent search to ensure all pertinent articles were identified. The reference sections of each article were also reviewed. Pertinent articles were evaluated by each author for inclusion. Articles were eligible for inclusion if the participants were taking DOAC therapy surrounding a dental procedure known to have low-to-moderate risk of bleeding. Studies could be prospective or retrospective and included case reports, case series, and clinical trials. Articles were excluded if they assessed dental procedures known to carry a high risk of bleeding or were review articles. Twenty-five articles were identified, 5 of which met inclusion criteria including 2 case series, 1 retrospective study, and 2 prospective trials. Variation in the management of DOAC therapy surrounding these procedures was found. Among patients undergoing low-to-moderate risk dental procedures while receiving DOAC therapy, bleeding rates were low regardless of whether the DOAC was held or continued surrounding the procedure. Documented bleeding was mild and easily controlled by local hemostatic measures. Patients can safely continue DOAC therapy surrounding these dental procedures.

Thromboprophylaxis With Apixaban in Patients Undergoing Major Orthopedic Surgery: Meta-Analysis and Trial-Sequential Analysis

BACKGROUND

Venous thromboembolism (VTE) is a potentially fatal complication of orthopedic surgery, and until recently, few antithrombotic compounds were available for postoperative thromboprophylaxis. The introduction of the non–vitamin K antagonists oral anticoagulants (NOAC), including apixaban, has extended the therapeutic armamentarium in this field. Therefore, estimation of NOAC net clinical benefit in comparison with the established treatment is needed to inform clinical decision making.

OBJECTIVES

Systematic review to assess the efficacy and safety of apixaban 2.5 mg twice a day versus low-molecular-weight heparins (LMWH) for thromboprophylaxis in patients undergoing knee or hip replacement.

DATA SOURCES

MEDLINE, Embase, and CENTRAL were searched from inception to September 2016, other systematic reviews, reference lists, and experts were consulted.

STUDY ELIGIBILITY CRITERIA, PARTICIPANTS, AND INTERVENTION

All major orthopedic surgery randomized controlled trials comparing apixaban 2.5 mg twice daily with LMWH, reporting thrombotic and bleeding events.

DATA EXTRACTION

Two independent reviewers, using a predetermined form.

STUDY APPRAISAL AND SYNTHESIS METHODS

The Cochrane tool to assess risk bias was used by two independent authors. RevMan software was used to estimate pooled risk ratio (RR) and 95% confidence intervals (95% CI) using random-effects meta-analysis. Trial sequential analysis (TSA) was performed in statistical significant results to evaluate whether cumulative sample size was powered for the obtained effect. Overall confidence in cumulative evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) Working Group methodology.

RESULTS

Four studies comparing apixaban 2.5 mg twice daily with LMWH were included, with a total of 11.828 patients (55% undergoing knee and 45% hip replacement). The overall risk of bias across studies was low. In comparison with LMWH (all regimens), apixaban showed a significantly lower risk of VTE events and overall mortality combined (RR: 0.63, 95% CI: 0.42–0.95, I2 = 84%, n = 8346), but not of major VTE events (RR: 0.62, 95% CI: 0.32–1.19, I2 = 63%, n = 9493), or of symptomatic VTE events and VTE-related mortality combined (RR: 1.14, 95% CI: 0.68–1.90, I2 = 0%, n = 11 879). Trial sequential analysis showed that the risk reduction obtained for VTE and mortality was based on underpowered cumulative sample size and effect dimension. Subgroup analysis according to LMWH regimens showed that apixaban reduced the risk of VTE events and overall mortality, and major VTE events, when compared with LMWH once daily, without differences between apixaban and LMWH twice daily.

CONCLUSIONS

There is low to moderate evidence that in patients undergoing knee or hip replacement, apixaban seems equally effective and safe to LMWH twice a day. When compared with LMWH once a day, apixaban seems a superior thromboprophylaxis option. However, the results are underpowered which precludes definite answers regarding the true net clinical benefit of apixaban versus LMWH in this clinical context.

Economic Evaluations of New Oral Anticoagulants for the Prevention of Venous Thromboembolism After Total Hip or Knee Replacement: A Systematic Review

BACKGROUND

Total hip replacement (THR) and total knee replacement (TKR) surgeries are being performed with increasing regularity and are associated with a high risk of developing a venous thromboembolism (VTE). New oral anticoagulants (NOACs) may be more effective at preventing VTEs but are associated with more bleeding events versus traditional anticoagulants.

OBJECTIVE

The objective of this systematic review was to identify published economic analyses of NOACs for primary VTE prophylaxis following THR and TKR surgeries, and to summarise the modelling techniques used and the cost-effectiveness results.

METHODS

Electronic searches of MEDLINE, EconLit and The Cochrane Library were performed from January 2008 to February 2015. Reference lists of included articles and reviews were examined for relevant studies.

RESULTS

Sixteen relevant economic analyses were identified, all of which used decision-tree structures to model acute events after surgery; 13 included a chronic-phase Markov module to capture long-term complications of VTE and recurrent VTE events. All studies included prophylaxis-related major bleeding events and captured both symptomatic and asymptomatic VTE-related events; nine studies distinguished between distal and proximal deep vein thrombosis events. Overall, rivaroxaban dominated enoxaparin in eight of 11 studies and dalteparin in one study, dabigatran dominated enoxaparin in five of seven studies and apixaban dominated enoxaparin in two of two studies. Rivaroxaban dominated dabigatran in four of four studies, apixaban dominated dabigatran in two of two studies and rivaroxaban dominated apixaban in one study.

CONCLUSIONS

The economic analyses showed reasonable consistency in the model structures used and the events captured. The results strongly suggested that NOACs are cost effective alternatives to low molecular-weight heparin. Dabigatran appeared to be the least cost effective NOAC. More research is needed to assess the cost effectiveness of apixaban and edoxaban.

Evolving Treatments for Arterial and Venous Thrombosis: Role of the Direct Oral Anticoagulants

The direct oral anticoagulants (DOACs) represent a major advance in oral anticoagulant therapy and have replaced the vitamin K antagonists as the preferred treatment for many indications. By simplifying long-term anticoagulant therapy and improving its safety, the DOACs have the potential to reduce the global burden of thrombosis. Postmarketing studies suggest that the favorable results achieved with DOACs in the randomized controlled trials can be readily translated into practice, but highlight the need for appropriate patient, drug and dose selection, and careful follow-up. Leveraging on their success to date, ongoing studies are assessing the utility of DOACs for the prevention of thrombosis in patients with embolic stroke of unknown source, heart failure, coronary artery disease, peripheral artery disease, antiphospholipid syndrome, and cancer. The purpose of this article is to (1) review the pharmacology of the DOACs, (2) describe the advantages of the DOACs over vitamin K antagonists, (3) summarize the experience with the DOACs in established indications, (4) highlight current challenges and limitations, (5) highlight potential new indications; and (6) identify future directions for anticoagulant therapy.

Direct oral anticoagulants and venous thromboembolism

Venous thromboembolism (VTE), consisting of deep vein thrombosis and pulmonary embolism, is a major clinical concern associated with significant morbidity and mortality. The cornerstone of management of VTE is anticoagulation, and traditional anticoagulants include parenteral heparins and oral vitamin K antagonists. Recently, new oral anticoagulant drugs have been developed and licensed, including direct factor Xa inhibitors (e.g. rivaroxaban, apixaban and edoxaban) and thrombin inhibitors (e.g. dabigatran etexilate). This narrative review focusses on the characteristics of these direct anticoagulants and the main results of published clinical studies on their use in the prevention and treatment of VTE.

[Posttraumatic thromboembolic complications: Incidence, risk factors, pathophysiology and prevention]

Venous thromboembolism (VTE) remains a major challenge in critically ill patients. Subjects admitted in intensive care unit (ICU), in particular trauma patients, are at high-risk for both deep vein thrombosis (DVT) and pulmonary embolism (PE). The rate of symptomatic PE in injured patients has been reported previously ranging from 1 to 6%. The high incidence of posttraumatic venous thromboembolic events is well known. In fact, major trauma is a hypercoagulable state. Several factors placing the individual patient at a higher risk for the development of DVT and PE have been suggested: high ISS score, meningeal hemorrhage and spinal cord injuries have frequently been reported as a significant risk factor for VTEs after trauma. Posttraumatic pulmonary embolism traditionally occurs after a period of at least 5 days from trauma. The prevention can reduce the incidence and mortality associated with the pulmonary embolism if it is effective. There is no consensus is now available about the prevention of venous thromboembolism in trauma patients.

Anticoagulation therapy and proximal femoral fracture treatment: An update

Hip fractures in the elderly population have become a 'disease' with increasing incidence.Most of the geriatric patients are affected by a number of comorbidities.Coagulopathies continue to be a special point of interest for the orthopaedic trauma surgeon, with the management of this high-risk group of patients a hot topic of debate among the orthopaedic community.While a universal consensus on how to manage thromboprophylaxis for this special cohort of patients has not been reached, multiple attempts to define a widely accepted protocol have been published. Cite this article: Ktistakis I, Giannoudis V, Giannoudis PV. Anticoagulation therapy and proximal femoral fracture treatment: an update. EFORT Open Rev 2016;1:310-315. DOI: 10.1302/2058-5241.1.160034.