Thromboprophylaxis in patients older than 75 years or with moderate renal impairment undergoing knee or hip replacement surgery [corrected]

Comparison of low molecular weight heparin, aspirin, and their combination for the prevention of thrombosis after total knee arthroplasty in obese patients

Purpose

Patients undergoing total knee arthroplasty (TKA) are at a high risk of thromboembolic events, which is higher in obese patients. Determining the appropriate prophylaxis for venous thromboembolism (VTE) in obese patients is challenging. Therefore, we aimed to compare the effects of low molecular weight heparin (LMWH) with aspirin (ASA) and their combination for the prevention of thromboembolic events after TKA in obese patients.

Methods

In a retrospective study, 245 obese patients with BMIs over 30 who underwent TKA were enroled. Eligible patients were divided into three groups: Group A was given LMWH sodium (Clexane®) for 14 days, Group B was given ASA for 14 days, and Group C was given LMWH sodium (Clexane®) for 5 days and then ASA twice daily for the days between 5 and 14 postoperatively. The primary outcome was the incidence of VTE within three months. Secondary outcomes included routine laboratory evaluations (PT, PTT, INR, Hb, Hct, platelets, BUN and Cr) and adverse effects of ASA and LMWH, such as bleeding, anaemia, thrombocytopenia, and gastrointestinal or neurological symptoms.

Results

Regarding the incidence of DVT and PTE, we did not observe significant differences between groups (p > 0.05). A total of seven symptomatic VTE was observed in six patients. We observed two cases with PE who were in the Clexane group. Moreover, five individuals had DVT in the follow-up: three cases in the Clexane group, one in the ASA group, and one in the ASA + Clexane group, which was not statistically significant (p > 0.05). There were no differences between groups regarding the risk of adverse events and complications.

Conclusion

We found that ASA is not inferior to enoxaparin in reducing VTE after TKA in obese patients. Therefore, given ASA's low cost and greater convenience, it may be considered a reasonable alternative for extended VTE prophylaxis for TKA surgery in obese patients.

Level of Evidence

Level III.

Efficacy and safety of anticoagulant for treatment and prophylaxis of VTE patients with renal insufficiency: a systemic review and meta-analysis

Patients with venous thromboembolism (VTE) comorbid renal insufficiency (RI) are at higher risk of bleeding and thrombosis. Recommendations in guidelines on anticoagulation therapy for those patients remain ambiguous. The goal of this study is to compare the efficacy and safety between different anticoagulant regimens in VTE patients comorbid RI at different stages of treatment and prophylaxis. We performed English-language searches of Pubmed, EMBASE, and Web of Science (inception to Nov 2022). RCTs evaluated anticoagulants for VTE treatment at the acute phase, extension phase, and prophylaxis in patients with RI and reported efficacy and safety outcomes were selected. The methodological quality of the studies was assessed at the outcome level using the risk-of-bias assessment tool developed by the Cochrane Bias Methods Group. A meta-analysis of twenty-five RCTs was conducted, comprising data from twenty-three articles, encompassing a total of 9,680 participants with RI. In the acute phase, the risk of bleeding was increased with novel oral anticoagulants (NOACs) compared to LMWH (RR 1.29, 95% CI 1.04-1.60). For the prophylaxis of VTE, NOACs were associated with an elevated risk of bleeding compared with placebo (RR 1.31, 95%CI 1.02-1.68). In comparison to non-RI patients, both NOACs and vitamin K antagonists (VKA) could increase the risk of bleeding among RI patients (RR 1.45, 95%CI 1.14-1.84 and RR 1.53, 95%CI 1.25-1.88, respectively) during acute phase, while NOACs may increase the incidence of VTE in RI population (RR 1.74, 95%CI 1.29-2.34). RI patients who are under routine anticoagulation have a significantly higher risk of adverse outcomes. LMWH is the most effective and safe option for VTE treatment or prophylaxis in patients with RI.

Anticoagulant for treatment and prophylaxis of venous thromboembolism patients with renal dysfunction: A systematic review and network meta-analysis

Objective

The aim of this study was to compare the efficacy and safety for particular regimen and dosage in venous thromboembolism (VTE) patients with renal insufficiency.

Methods

English language searches of PubMed, Embase, and Web of Science (inception to May 2021). RCTs evaluating anticoagulants for VTE treatment at acute phase, extension phase, and VTE prophylaxis in patients with renal insufficiency and reporting efficacy (death, recurrence, or occurrence of VTE) and safety (bleeding) outcomes were selected. The methodological quality of each study included was assessed at the outcome level using the risk-of-bias assessment tool developed by the Cochrane Bias Methods Group.

Results

Twenty-one trials that involved 76,574 participants and 8,972 (11.7%) patients with renal insufficiency were enrolled, including 10 trials on VTE treatment in acute phase (3–12 months), four trials on VTE treatment in extension phase (6–36 months), and seven trials for VTE prophylaxis. For acute VTE treatment, compared with dabigatran etexilate, apixaban (RR 5.90, 95%CI 1.00–34.60) and rivaroxaban (RR 6.18, 95%CI 1.17–32.75) were significantly associated with increased risk of death or recurrence. For extension treatment of VTE, aspirin had the highest probability of the most effective and safest treatment, followed by apixaban. For VTE prophylaxis, compared with enoxaparin, desirudin was associated with lower risk of VTE occurrence (RR 0.56, 95% CI 0.34–0.91), but had higher risk of bleeding than dabigatran etexilate.

Conclusion

The network meta-analysis informs the optimal choice of anticoagulants and their particular dosage for treatment and prophylaxis of VTE patients comorbid renal insufficiency.

Systematic review registration

www.crd.york.ac.uk/prospero/, identifier: CRD42021254086.

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.

The use of direct oral anticoagulants in chronic kidney disease

Increasing use of direct oral anticoagulants (DOACs) has made management of non-valvular atrial fibrillation and venous thromboembolism easier in most patients. But the presence of co-existing renal impairment could render the use of DOACs problematic because all of these drugs have varying degrees of renal excretion. In this paper we address misconceptions about the safety and efficacy of DOACs in moderate-severe renal impairment by presenting a summary of the literature from phase III trials and real-world studies. It also addresses the important consideration of correct estimate of renal function for DOAC dosing. It is hoped that the review will serve as a valuable resource for clinicians involved in anticoagulation decision-making in patients with renal impairment to guide the choice of most suitable agent. Accurate dosing is of particular relevance as registry data suggests it is done inconsistently and may be resulting in avoidable thromboembolic and bleeding events.

Length of hospitalization and mortality for bleeding during treatment with warfarin, dabigatran, or rivaroxaban

Background

Different outcomes among patients hospitalized for bleeding after starting anticoagulation could influence choice of anticoagulant. We compared length of hospitalization, proportion of Intensive Care Unit (ICU) admissions, ICU length of stay, and 30- and 90-day mortality for adults with atrial fibrillation hospitalized for bleeding after starting warfarin, dabigatran, or rivaroxaban.

Methods

An US commercial database of 38 million members from 1 November 2010 to 31 March 2014 was used to examine adults with atrial fibrillation hospitalized for bleeding after starting warfarin (2,446), dabigatran (442), or rivaroxaban (256). Outcomes included difference in mean total length of hospitalization, proportion of ICU admissions, mean length of ICU stay, and all-cause 30- and 90-day mortality.

Results

Warfarin users were older and had more comorbidities. Multivariable regression modeling with propensity score weighting showed warfarin users were hospitalized 2.0 days longer (95% CI 1.8–2.3; p < 0.001) than dabigatran users and 2.6 days longer (95% CI 2.4–2.9; p < 0.001) than rivaroxaban users. Dabigatran users were hospitalized 0.6 days longer (95% CI 0.2–1.0; p = 0.001) than rivaroxaban users. There were no differences in the proportion of ICU admissions. Among ICU admissions, warfarin users stayed 3.0 days (95% CI 1.9–3.9; p < 0.001) longer than dabigatran users and 2.4 days longer (95% CI 0.9–3.7; p = 0.003) than rivaroxaban users. There was no difference in ICU stay between dabigatran and rivaroxaban users. There were no differences in 30- and 90-day all-cause mortality.

Conclusions

Rivaroxaban and dabigatran were associated with shorter hospitalizations; however, there were no differences in 30- and 90-day mortality. These findings suggest bleeding associated with the newer agents is not more dangerous than bleeding associated with warfarin.

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.

An open-label study of the pharmacokinetics and pharmacodynamics of dabigatran etexilate 150mg once daily in Caucasian patients with moderate renal impairment undergoing primary unilateral elective total knee or hip replacement surgery

BACKGROUND

In adults with moderate renal impairment (creatinine clearance [CrCl] 30-50mL/min) undergoing total hip or knee replacement (THR/TKR), the recommended dose of dabigatran etexilate is 150mg once daily (qd). We investigated the steady state pharmacokinetics, pharmacodynamics and safety in these patients.

METHODS

Single-arm, open-label phase 4 study (NCT01184989) in Caucasian patients receiving dabigatran etexilate 75mg 1-4h after surgery and 150mg qd on days 2-10 (TKR) or days 2-35 (THR). Plasma total dabigatran concentrations (day 6±1) were determined by high-performance liquid chromatography tandem mass spectrometry and indirectly using the commercially available diluted thrombin time (dTT) assay (Hemoclot® Thrombin Inhibitors).

RESULTS

Of 112 patients (mean CrCl 42.5mL/min, age 79.1years, 69.6% female), 100 completed the study. Geometric mean trough and peak dabigatran concentrations were 47.5ng/mL (10th-90th percentile 19.7-120) and 166ng/mL (49.1-364), respectively. There were four major bleeding events and no venous thromboembolic events. Dabigatran concentrations determined from dTT (and falling within the assay range of 50-500ng/mL) underestimated actual values by 7.6% (90% confidence interval 5.3, 9.9), which is within the acceptance limits of ±15%.

CONCLUSIONS

These findings in Caucasians with moderate renal impairment undergoing THR or TKR support the use of the 150mg qd dose of dabigatran etexilate. With adequate set-up, calibration and quality control the dTT assay might be appropriate for situations, such as serious bleeding or a need for urgent surgery, where determination of dabigatran levels would be helpful.

New oral pharmacotherapeutic agents for venous thromboprophylaxis after total hip arthroplasty

Patients undergoing total hip arthroplasty (THA) are at high risk for developing venous thromboembolism and, therefore, require short term prophylaxis with antithrombotic agents. Recently, target specific oral anticoagulants (TSOA) including the direct thrombin inhibitor, dabigatran, and the factor Xa inhibitors rivaroxaban, apixaban, and edoxaban have been approved for THA thrombopropylaxis in various countries. The TSOAs provide a rapid acting, oral alternative to parenteral agents including low-molecular weight heparins (LMWH) and fondaparinux; and compared to warfarin, they do not require routine laboratory monitoring and possess much fewer drug-drug interactions. Based on phase III clinical studies, TSOAs have established themselves as an effective and safe option for thromboprophylaxis after THA compared to LMWH, particularly enoxaparin, but require additional evaluation in specific populations such as the renally impaired or elderly. The ability to monitor and reverse these TSOAs in the case of bleeding complications or suspected sub- or supra-therapeutic anticoagulation is of importance, but remains investigational. This review will focus on the drug-specific characteristics, efficacy, safety, and economic impact of the TSOAs for thromboprophylaxis following THA, as well as the aspects of therapeutic monitoring and anticoagulation reversal in the event of bleeding complications or a need for urgent reversal.

Advantages and limitations of the new anticoagulants

During recent years, three new anticoagulants (dabigatran, rivaroxaban and apixaban) have been introduced to the market, probably with one more anticoagulant (edoxaban) in the next 2 years. This review is not intended to compare the efficacy and risks of these new agents, but rather to detail the advantages and limitations. The pharmacokinetic characteristics of these drugs have few drug and food interactions, predictable dose responses, and rapid onset and offset, thus resulting in simplified management of the patient requiring anticoagulant therapy. No routine laboratory monitoring is required. A somewhat unexpected, but exciting observation involving the new anticoagulants, is the uniform reduction in intracranial bleeding by one-half compared with warfarin. The potential limitations of the new anticoagulants include uncertainty regarding assessment of drug levels, safe drug levels for major surgery, management of major bleeding, renal dependence, multiple dose regimens, adherence in the absence of frequent monitoring and unknown, rare side effects that were not captured in the trials. This review should clarify some of these concerns.

The necessity of pharmacological prophylaxis against venous thromboembolism in major joint arthroplasty

PURPOSE

Venous thromboembolism (VTE) is a recognised post-operative complication of major lower limb joint arthroplasty. Current National Institute for Health and Clinical Excellence (NICE) guidelines suggest the use of both mechanical and pharmacological prophylaxis following hip and knee replacement. Since the introduction of enhanced recovery programmes following hip and knee arthroplasty the requirement for routine pharmacological VTE prophylaxis has been questioned. The purpose of this study was to assess the efficacy of pharmacological prophylaxis against symptomatic VTE in patients undergoing hip and knee arthroplasty under an enhanced recovery programme.

METHODS

Symptomatic VTE incidence was audited in 1,100 patients undergoing primary or revision total hip or knee arthroplasty at the same hospital with only mechanical prophylaxis from 2007 to 2009. Following addition of chemical prophylaxis (enoxaparin) symptomatic VTE incidence in 522 patients undergoing primary or revision total hip or knee arthroplasty from 2011 to 2012 was re-audited.

RESULTS

In the mechanical prophylaxis group incidence of DVT was 0.73 % [95 % confidence interval (CI) 0.37-1.43 %] and incidence of pulmonary embolism (PE) 0.91 % (95 % CI 0.49-1.67 %). Following addition of pharmacological prophylaxis incidence of DVT was 0.57 % (95 % CI 0.20-1.68 %) and incidence of PE 1.15 % (95 % CI 0.53-2.48 %).

CONCLUSIONS

We found no statistically significant difference in symptomatic VTE incidence following the addition of enoxaparin. We question whether routine pharmacological prophylaxis still has a role following total hip and knee arthroplasty. Peri-operative optimisation, including post-operative analgesia and mobility, with current enhanced recovery programmes may be sufficient. As anticoagulants carry increased risk of post-operative bleeding and wound ooze, in addition to significant cost implications, their role remains controversial.

Antithrombotic prophylaxis in major orthopaedic surgery: an historical overview and update of current recommendations

The risk of venous thromboembolism following major orthopaedic procedures, such as joint arthroplasty and hip fracture surgery, are well recognised and represent one of the major challenges in orthopaedic practice, having in mind the increasing number of arthroplasties of the hip and knee done worldwide per year and their successful outcome. This potentially fatal complication remains a challenge in orthopaedic practice. The percentage of patients in whom antithrombotic prophylaxis has not been administrated or has been inadequate may reach 50%. Until recently, anticoagulant prophylaxis with low molecular weight heparins (LMWHs) has been a "gold standard". LMWHs are indirect inhibitors of the clotting factors Xa and thrombin and are administered by daily subcutaneous injection. Their efficacy has been proven in numerous clinical trials and the rate of complications with their use is relatively low. However these compounds are associated with a failure rate and are inconvenient to administer, requiring subcutaneous injection, leading to inadequate compliance. For these reasons postoperative thrombembolism continues to occur in up to 10% of this patient population. Recently, novel oral anticoagulants have been introduced into practice for thromboprophylaxis after joint arthroplasy and hip fracture surgery. These drugs are direct thrombin inhibitors (dabigatran) or direct factor Xa inhibitors (rivaroxaban, apixaban and edoxaban). These oral drugs have the same efficacy as the LMWHs with the same or slightly more clinically significant haemorrhage as their main side effect. Their ease of administration and favourable clinical profile makes them an important addition to the therapeutic armamentarium available for venous thromboprophylaxis. In this paper we review the aetiology and pathogenesis of venous thromboembolism and present the various alternatives for its prevention after major orthopaedic surgical procedures with emphasis on the new oral drugs.

A systematic review of venous thromboembolism prophylaxis strategies in patients with renal insufficiency, obesity, or on antiplatelet agents

BACKGROUND

There is uncertainty about optimal strategies for venous thromboembolism (VTE) prophylaxis among select populations such as patients with renal insufficiency, obesity, or patients taking antiplatelet drugs including aspirin. Their physiologies make prophylaxis particularly challenging.

PURPOSE

We performed a comparative effectiveness review of the literature on efficacy and safety of VTE prophylaxis in these populations.

DATA SOURCES

We searched MEDLINE, EMBASE, SCOPUS, CINAHL, International Pharmaceutical Abstracts, clinicaltrial.gov, and the Cochrane Library through August 2012. Eligible studies included controlled trials and observational studies.

DATA EXTRACTION

Two reviewers evaluated studies for eligibility, serially abstracted data, and independently evaluated the risk of bias and strength of evidence supporting interventions to prevent VTE in these populations.

RESULTS

After a review of 30,902 citations, we identified 9 controlled studies, 5 of which were trials, and the other 4 were observational studies. Five articles addressed prophylaxis of patients with renal insufficiency, 2 addressed obese patients, and 2 addressed patients on antiplatelet agents. No study tested prophylaxis in underweight patients or those with liver disease. The majority of observational studies had a high risk of bias. The strength of evidence ranged from low to insufficient regarding the comparative effectiveness and safety of VTE prophylaxis among these patients.

CONCLUSION

The current evidence is insufficient regarding optimal VTE prophylaxis for patients with renal insufficiency, obesity, or those who are on antiplatelet drugs including aspirin. High-quality studies are needed to inform clinicians about the best VTE prophylaxis for these patients.

Anticoagulation; New Pharmacologic Methods to Prevent Venous Thromboembolism in Older Adults: A Meta-Analysis

OBJECTIVE

To conduct a meta-analysis of randomized controlled trials that used newly approved drugs to prevent venous thromboembolism (VTE) in older adults.

DATA SOURCES

PubMed, EMBASE, and International Pharmaceutical Abstracts (through July 2012).

STUDY SELECTION AND DATA EXTRACTION

Full-text clinical trial reports were included if they (1) had a randomized controlled design, (2) used a pharmacologic method approved or anticipated to be approved in the US, (3) enrolled at least 300 subjects, (4) enrolled subjects with a mean age of 65 years or older or performed a subgroup analysis in adults in that population, and (5) scored at least 7 of 8 on quality criteria for clinical trials. Twenty unique studies met the inclusion criteria.

DATA SYNTHESIS

The most common indications for pharmacologic VTE prophylaxis in the identified studies were orthopedic procedures involving the lower extremities and general surgery. Only 2 studies enrolled acutely ill patients admitted to hospital medical services. Fondaparinux (5 studies) was more effective than enoxaparin in preventing VTE (OR 0.5, 95% CI 0.37–0.67; p < 0.00001) but had more bleeding (OR 1.48, 95% CI 1.05–2.08; p = 0.03). Dabigatran 150 mg once daily (3 studies) was less effective than enoxaparin in preventing VTE (OR 1.30, 95% CI 1.09–1.56; p = 0.004) with a similar bleeding risk (OR 0.74, 95% CI 0.46–1.22; p = 0.24). Dabigatran 220 mg once daily (4 studies) was as effective as enoxaparin in preventing VTE (OR 1.02, 95% CI 0.83–1.26; p = 0.84) and had similar bleeding (OR 1.08, 95% CI 0.66–1.76; p = 0.76). Rivaroxaban (4 studies) was more effective than enoxaparin in preventing VTE (OR 0.38, 95% CI 0.23–0.61; p < 0.0001) with a trend toward a higher rate of bleeding (OR 1.8, 95% CI 0.90–3.60; p = 0.09). Apixaban (5 studies) was more effective than enoxaparin in preventing VTE (OR 0.64, 95% CI 0.43–0.96; p = 0.0002) and had a similar rate of bleeding (OR 0.71, 95% CI 0.42–1.21; p = 0.21).

CONCLUSIONS

When compared to enoxaparin, newer drugs exhibit slightly different safety and efficacy profiles when used for VTE prevention in older adults undergoing major orthopedic surgery. There are insufficient data for other indications. The benefits and risks of new pharmacologic methods of VTE prevention are unclear in the oldest old (age ≥85 years) and in those admitted to a hospital for an acute medical illness or to a skilled nursing facility.

The discovery of dabigatran etexilate

Thromboembolic disease is a major cause of mortality and morbidity in the developed world and is caused by an excessive stimulation of coagulation. Thrombin is a key serine protease in the coagulation cascade and numerous efforts have been made to develop safe and effective orally active direct thrombin inhibitors (DTIs). Current anticoagulant therapy includes the use of indirect thrombin inhibitors (e.g., heparins, low-molecular-weight-heparins) and vitamin K antagonists such as warfarin. However there are several caveats in the clinical use of these agents including narrow therapeutic window, parenteral delivery, and food- and drug-drug interactions. Dabigatran is a synthetic, reversible DTI with high affinity and specificity for its target binding both free and clot-bound thrombin, and offers a favorable pharmacokinetic profile. Large randomized clinical trials have demonstrated that dabigatran provides comparable or superior thromboprophylaxis in multiple thromboembolic disease indications compared to standard of care. This minireview will highlight the discovery and development of dabigatran, the first in a class of new oral anticoagulant agents to be licensed worldwide for the prevention of thromboembolism in the setting of orthopedic surgery and stroke prevent in atrial fibrillation.

Acute management of bleeding in patients on novel oral anticoagulants

Novel oral anticoagulants that directly inhibit thrombin (dabigatran) or factor Xa (rivaroxaban, apixaban) are currently available for prevention of venous thromboembolism (VTE) after orthopaedic surgery, treatment of acute VTE, and prevention of arterial thromboembolism in non-valvular atrial fibrillation. These agents offer advantages over VKAs, including rapid onset, shorter half-lives, fewer drug interactions, and lack of need for routine monitoring. However, there are no established agents to reverse their anticoagulant effect. We review the risk of bleeding with the novel oral anticoagulants and the limitations of conventional coagulation assays for measuring anticoagulant effect. We provide an approach to the management of patients with bleeding complications with evidence for various interventions for reversal, where available.

Dabigatran etexilate: a review of its use for the prevention of venous thromboembolism after total hip or knee replacement surgery

Dabigatran etexilate (Pradaxa®, Pradax™, Prazaxa®) is indicated for the primary prevention of venous thromboembolic (VTE) events in adults who have undergone elective total hip replacement (THR) or total knee replacement (TKR) surgery. This article reviews the clinical efficacy and tolerability of oral dabigatran etexilate in patients undergoing major orthopaedic surgery, as well as summarizing its pharmacological properties and results of a cost-utility analysis. The discussion of clinical trial data focuses on comparative trials with the EU approved dosage regimen of once-daily subcutaneous enoxaparin sodium 40 mg. Dabigatran etexilate is an oral prodrug of the potent, rapidly acting, reversible, competitive inhibitor of thrombin, dabigatran. Dabigatran has predictable and consistent anticoagulant effects and does not require routine coagulation monitoring or dose titration. In the large, randomized, double-blind, phase III, noninferiority trials, RE-MODEL, RE-NOVATE and RE-NOVATE II, oral dabigatran etexilate, at dosages of 150 and 220 mg once daily, initiated postoperatively was shown to be noninferior to subcutaneous enoxaparin sodium 40 mg once daily (initiated prior to surgery) with regard to the incidence of the composite of total VTE events and all-cause mortality in patients undergoing TKR or THR surgery. In general, oral dabigatran etexilate was well tolerated in clinical trials of patients undergoing major orthopaedic surgery. There were no significant between-group differences in bleeding complications, including major bleeding, clinically relevant non-major bleeding or minor bleeding between the dabigatran etexilate or enoxaparin sodium groups. In addition, a cost-utility analysis from the perspective of the UK National Health Service indicated that dabigatran etexilate 220 mg once daily is dominant (i.e. more effective and less costly) to enoxaparin sodium 40 mg once daily in patients undergoing THR or TKR. Additional head-to-head comparisons would be beneficial to more definitively position dabigatran etexilate relative to other available oral treatment options for VTE prophylaxis, such as rivaroxaban and apixaban. In the meantime, dabigatran etexilate offers a convenient, effective and generally well tolerated treatment option for the prophylaxis of VTE in patients undergoing TKR and THR surgery.

Type of anaesthesia and the safety and efficacy of thromboprophylaxis with enoxaparin or dabigatran etexilate in major orthopaedic surgery: pooled analysis of three randomized controlled trials

Background

There has been a shift towards greater use of neuraxial over general anaesthesia for patients undergoing total hip or knee arthroplasty. Furthermore, suggestions that peripheral nerve block may reduce adverse effects have recently been put forward. Although older studies showed a reduction in venous thromboembolism (VTE) with neuraxial compared with general anaesthesia, this difference has not been confirmed in studies using effective current thromboprophylaxis. We used a large data set to investigate the pattern of anaesthesia usage, and whether anaesthesia type affects efficacy and bleeding outcomes of thromboprophylaxis overall, within each treatment group, or for the novel oral anticoagulant dabigatran etexilate versus enoxaparin.

Methods

Three previously reported trials compared 220 mg and 150 mg dabigatran etexilate once daily with enoxaparin after knee or hip arthroplasty. A pooled analysis was performed in patients receiving general or neuraxial anaesthesia, or the combination of either with peripheral nerve block (n = 8062). Outcome measures were major VTE plus VTE-related mortality, major bleeding and major plus clinically relevant bleeding events.

Results

General, neuraxial and combination anaesthesia were used in 29%, 52% and 19% of patients, respectively. Differences in efficacy and safety between anaesthesia subgroups were small and not significant, except for a slightly higher rate of major VTE and VTE-related mortality with general versus neuraxial anaesthesia (odds ratio: 1.40; 95% confidence interval: 1.03–1.90; p = 0.035) in the overall population. There were no significant effects of anaesthesia type on efficacy or safety of dabigatran etexilate versus enoxaparin.

Conclusions

Anaesthesia type did not greatly affect efficacy and safety outcomes in the pooled population of all three treatment groups. The efficacy and safety of dabigatran etexilate was comparable with enoxaparin, regardless of type of anaesthesia.

Trial registration

ClinicalTrials.gov identifiers: NCT00168805, NCT00168818, NCT00152971.

Dabigatran, rivaroxaban, or apixaban versus enoxaparin for thromboprophylaxis after total hip or knee replacement: systematic review, meta-analysis, and indirect treatment comparisons

OBJECTIVE

To analyse clinical outcomes with new oral anticoagulants for prophylaxis against venous thromboembolism after total hip or knee replacement.

DESIGN

Systematic review, meta-analysis, and indirect treatment comparisons.

DATA SOURCES

Medline and CENTRAL (up to April 2011), clinical trials registers, conference proceedings, and websites of regulatory agencies.

STUDY SELECTION

Randomised controlled trials of rivaroxaban, dabigatran, or apixaban compared with enoxaparin for prophylaxis against venous thromboembolism after total hip or knee replacement. Two investigators independently extracted data. Relative risks of symptomatic venous thromboembolism, clinically relevant bleeding, deaths, and a net clinical endpoint (composite of symptomatic venous thromboembolism, major bleeding, and death) were estimated using a random effect meta-analysis. RevMan and ITC software were used for direct and indirect comparisons, respectively.

RESULTS

16 trials in 38,747 patients were included. Compared with enoxaparin, the risk of symptomatic venous thromboembolism was lower with rivaroxaban (relative risk 0.48, 95% confidence interval 0.31 to 0.75) and similar with dabigatran (0.71, 0.23 to 2.12) and apixaban (0.82, 0.41 to 1.64). Compared with enoxaparin, the relative risk of clinically relevant bleeding was higher with rivaroxaban (1.25, 1.05 to 1.49), similar with dabigatran (1.12, 0.94 to 1.35), and lower with apixaban (0.82, 0.69 to 0.98). The treatments did not differ on the net clinical endpoint in direct or indirect comparisons.

CONCLUSIONS

A higher efficacy of new anticoagulants was generally associated with a higher bleeding tendency. The new anticoagulants did not differ significantly for efficacy and safety.