Cost-Effectiveness of Apixaban Versus Other New Oral Anticoagulants for Stroke Prevention in Atrial Fibrillation

Background

Apixaban (5 mg BID), dabigatran (available as 150 mg and 110 mg BID in Europe), and rivaroxaban (20 mg once daily) are 3 novel oral anticoagulants (NOACs) currently approved for stroke prevention in patients with atrial fibrillation (AF).

Objective

The objective of this study was to evaluate the cost-effectiveness of apixaban against other NOACs from the perspective of the United Kingdom National Health Services.

Methods

A Markov model was developed to evaluate the pharmacoeconomic impact of apixaban versus other NOACs over a lifetime. Pair-wise indirect treatment comparisons were conducted against other NOACs by using ARISTOTLE (Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation), RE-LY (Randomized Evaluation of Long-Term Anticoagulation Therapy), and ROCKET-AF (Rivaroxaban Once Daily Oral Direct Factor Xa Inhibition Compared With Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation) trial results for the following end points: ischemic stroke, hemorrhagic stroke, intracranial hemorrhage, other major bleeds, clinically relevant nonmajor bleeds, myocardial infarction, and treatment discontinuations. Outcomes were life-years, quality-adjusted life years gained, direct health care costs, and incremental cost-effectiveness ratios.

Results

Apixaban was projected to increase life expectancy versus other NOACs, including dabigatran (both doses) and rivaroxaban. A small increase in therapeutic management costs was observed with apixaban due to projected gains in life expectancy and lower discontinuation rates anticipated on apixaban versus other NOACs through lifetime. The estimated incremental cost-effectiveness ratio was £9611, £4497, and £5305 per quality-adjusted life-year gained with apixaban compared with dabigatran 150 mg BID, dabigatran 110 mg BID, and rivaroxaban 20 mg once daily, respectively. Sensitivity analyses indicated that results were robust over a wide range of inputs.

Conclusions

Although our analysis was limited by the absence of head-to-head trials, based on the indirect comparison data available, our model projects that apixaban may be a cost-effective alternative to dabigatran 150 mg BID, dabigatran 110 mg BID, and rivaroxaban 20 mg once daily for stroke prevention in AF patients from the perspective of the United Kingdom National Health Services.     

A review of apixaban for stroke prevention in atrial fibrillation: insights from ARISTOTLE

Atrial fibrillation (AF) is associated with significant mortality and morbidity, and stroke represents the most-feared complication. Consequently, AF treatment has focused on thromboprophylaxis, with warfarin as the mainstay of therapy. However, concerns over ease of use and safety have limited its use. Three novel oral anticoagulants have been approved for use in stroke prevention in AF based on randomized data: 1) dabigatran, studied in Randomized Evaluation of Long-term Anticoagulation Therapy (RE-LY); 2) rivaroxaban, studied in Rivaroxaban Once-daily, Oral, Direct Factor Xa Inhibition Compared with Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation (ROCKET AF); and 3) apixaban, studied inApixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation (ARISTOTLE). In this review, we focus on apixaban and discuss subgroup analyses that have been performed in the three trials comparing novel oral anticoagulants with warfarin. We conclude with recommendations regarding further investigations.     

Novel Oral Anticoagulants for Stroke Prevention in Atrial Fibrillation: Focus on Apixaban

Stroke prevention in atrial fibrillation (AF) has been challenging over decades, mostly due to a number of difficulties associated with oral vitamin K antagonists (VKAs), which have been the most effective stroke prevention treatment for a long time. The oral direct thrombin inhibitors (e.g., dabigatran) and oral direct inhibitors of factor Xa (e.g., rivaroxaban, apixaban) have emerged recently as an alternative to VKAs for stroke prevention in AF. These drugs act rapidly, and have a predictable and stable dose-related anticoagulant effect with a few clinically relevant drug-drug interactions. The novel oral anticoagulants are used in fixed doses with no need for regular laboratory monitoring of anticoagulation intensity. However, each of these drugs has distinct pharmacological properties that could influence optimal use in clinical practice. The following phase 3 randomized trials with novel oral anticoagulants versus warfarin for stroke prevention in AF have been completed: the Randomized Evaluation of Long-term Anticoagulant therapy (RE-LY) trial with dabigatran, the Rivaroxaban Once daily oral direct Factor Xa inhibition Compared with vitamin K antagonism for prevention of stroke and Embolism Trial in Atrial Fibrillation (ROCKET-AF) trial with rivaroxaban, and the Apixaban for Reduction of Stroke and Other Thromboembolism Events in Atrial Fibrillation (ARISTOTLE) trial with apixaban. Moreover, the Apixaban Versus Acetylsalicylic Acid to prevent Strokes (AVERROES) trial included patients with AF who have failed or were unsuitable for warfarin, and compared apixaban versus aspirin for stroke prevention in AF. Overall, apixaban has two large trials for stroke prevention in AF showing benefits not only over warfarin, but also over aspirin among those patients who have failed or refused warfarin. In the ARISTOTLE trial, apixaban was superior to warfarin in the reduction of stroke or systemic embolism, major bleeding, intracranial hemorrhage, and all-cause mortality, with a similar reduction in the rate of ischemic stroke and better tolerability. When compared with aspirin in the AVERROES trial, apixaban was associated with more effective reduction of stroke, a similar risk of major bleeding, and better tolerability. In this review article, the authors summarize the current knowledge on novel oral anticoagulants and discuss the clinical aspects of their use for stroke prevention in AF, with particular emphasis on apixaban.     

心房颤动抗凝治疗进展

心房颤动是临床上最常见的心律失常,增加卒中风险。华法林抗凝效果虽已受到广泛的肯定,但同时存在出血风险、治疗窗狭窄、需要长期监测国际标准化比率以调整药量等缺点。新型口服抗凝药的应用如达比加群、利伐沙班、阿哌沙班可有效预防卒中及血栓栓塞。经皮左心耳封堵术亦可成为预防心房颤动血栓事件的有效替代治疗方式。     

Personalizing oral anticoagulant treatment in patients with atrial fibrillation

For decades, warfarin has remained the standard oral anticoagulation for stroke prevention in atrial fibrillation (AF). Three novel oral anticoagulants (NOACs) have been recently approved for stroke prevention in non-valvular AF: dabigatran, rivaroxaban and apixaban. Better pharmacological and clinical profiles make these newcomers a preferable alternative over warfarin. Current AF guidelines do not endorse NOACs over warfarin, or one NOAC over another. Indeed, choice of the anticoagulation regimen should be personalized based on the relative efficacy and safety of different agents across subgroups stratified by thrombotic and bleeding risk, as well as on other clinical factors, including anticoagulation control on warfarin, drug interactions, compliance and need for coagulation monitoring. This review appraises i) the randomized evidence on approved NOACs versus warfarin in AF across subgroups stratified by risk factors of stroke and bleeding and by the anticoagulation level reached on warfarin; and ii) clinical factors impacting on the anticoagulation regimen selection.     

Treatment Discontinuations With New Oral Agents for Long-term Anticoagulation: Insights From a Meta-analysis of 18 Randomized Trials Including 101,801 Patients

ObjectiveTo systematically examine discontinuation rates with new US Food and Drug Administration–approved oral anticoagulants (NOACs) in patients with various indications for long-term anticoagulation.Patients and MethodsPoor adherence to medications is considered a potential and frequent cause of treatment failure. We searched the PubMed, Cochrane Central Register of Controlled Trials, EMBASE, EBSCO, Web of Science, and CINAHL databases for articles published from January 1, 2001, through September 15, 2013. The following Medical Subject Heading terms and/or keywords were used for our database searches: rivaroxaban, dabigatran, apixaban, new oral anticoagulants, oral thrombin inhibitors, and oral factor Xa inhibitors. Articles in English that focused on randomized controlled trials (RCTs) comparing NOACs (apixaban, dabigatran, and rivaroxaban) with conventional therapy or placebo were abstracted. Independent extraction of relevant data was performed by 2 authors. The primary end point of interest was discontinuation due to all causes. Other end points of interest were discontinuation due to adverse events, consent withdrawal, and nonadherence.ResultsEighteen RCTs including a total of 101,801 patients were included for analysis. Total study drug discontinuation rates were not statistically different with NOACs in comparison to pharmacologically active comparators for treatment of venous thromboembolism/pulmonary embolism (risk ratio [RR], 0.91; 95% CI, 0.74-1.13; P=.40) and for NOACs in comparison to warfarin and aspirin for prevention of stroke in patients with atrial fibrillation (RR, 1.01; 95% CI, 0.87-1.17; P=.92). In contrast, in acute coronary syndromes, total study drug discontinuation with NOACs was significantly higher than with placebo (RR, 1.40; 95% CI, 1.07-1.83; P=.01). Overall discontinuations were comparable to those with active comparators.ConclusionStudy drug discontinuations with NOACs were not significantly different from those with conventional drugs in treatment of venous thromboembolism/pulmonary embolism and prevention of stroke in patients with atrial fibrillation but were worse in acute coronary syndromes as noted in evidence from contemporary RCTs.     

Pharmacological and Non-pharmacological Treatments for Stroke Prevention in Patients with Atrial Fibrillation

Atrial fibrillation (AF) is associated with significant risk of stroke and other thromboembolic events, which can be effectively prevented using oral anticoagulation (OAC) with either vitamin K antagonists (VKAs) or non-VKA oral anticoagulants (NOACs) dabigatran, rivaroxaban, apixaban, or edoxaban. Until recently, VKAs were the only available means for OAC treatment. NOACs had similar efficacy and were safer than or as safe as warfarin with respect to reduced rates of hemorrhagic stroke or other intracranial bleeding in the respective pivotal randomized clinical trials (RCTs) of stroke prevention in non-valvular AF patients. Increasing “real-world” evidence on NOACs broadly confirms the results of the RCTs. However, individual patient characteristics including renal function, age, or prior bleeding should be taken into account when choosing the OAC with best risk–benefit profile. In patients ineligible for OACs, surgical or interventional stroke prevention strategies should be considered. In patients undergoing cardiac surgery for other reasons, the left atrial appendage excision, ligation, or amputation may be the best option. Importantly, residual stumps or insufficient ligation may result in even higher stroke risk than without intervention. Percutaneous left atrial appendage occlusion, although requiring minimally invasive access, failed to demonstrate reduced ischemic stroke events compared to warfarin. In this review article, we summarize current treatment options and discuss the strengths and major limitations of the therapies for stroke risk reduction in patients with AF.     

Mixed Treatment Comparison Meta-Analysis of Aspirin,Warfarin, and New Anticoagulants for Stroke Prevention in Patients With Nonvalvular Atrial Fibrillation

Background

Warfarin and aspirin are used to prevent stroke in patients with atrial fibrillation (AF). There are inherent challenges with both treatments, including variable and inconsistent benefit and increased bleeding risks. The availability of new anticoagulants offers some alternatives.

Objective

A mixed treatment comparison meta-analysis to evaluate direct and indirect treatment data including aspirin, warfarin apixaban, dabigatran, edoxaban, and rivaroxaban for the prevention of primary or secondary stroke in patients with AF.

Methods

A comprehensive, systematic literature search was conducted to identify randomized trials comparing aspirin, warfarin, apixaban, dabigatran, edoxaban, and rivaroxaban in patients with AF requiring treatment for stroke prevention. Open-label and blinded designs were included if they evaluated any stroke or any bleeding event. Data on stroke and bleeding events were abstracted, verified, evaluated, scored, and entered into Aggregate Data Drug Information System version 1.16 to generate a mixed treatment comparison meta-analysis. Direct and indirect comparisons were evaluated, and we looked for inconsistency in closed loop structures. Data are reported as rate ratios with 95% credible intervals. In addition, we reviewed variance statistics and explored variance with node-splitting models.

Results

Our literature search yielded 30 articles, 21 of which were included. All treatments except aspirin reduced the risk of any stroke compared with placebo. Warfarin (0.43 [0.33–0.57]), apixaban (0.37 [0.27–0.54]), dabigatran (0.34 [0.21–0.57]), rivaroxaban (0.36 [0.22–0.60]), and aspirin with clopidogrel (0.73 [0.53–0.99]) were more protective than aspirin alone. Warfarin and the new anticoagulants were similar in the reduction of stroke, vascular death, and mortality. There was no difference in major bleeding between any treatment group. There were more nonmajor bleeding events when comparing warfarin and apixaban (1.83 [1.05–4.03]); no other differences between warfarin and the other new anticoagulants were found.

Conclusions

This mixed treatment comparison meta-analysis found similarity between warfarin and the new anticoagulants with the exception of one comparison, in which warfarin was associated with more non-major bleeding than apixaban. Thus, the new anticoagulants are therapeutically comparable when warfarin is inappropriate.     

Cost-effectiveness of Dabigatran Compared With Rivaroxaban for Prevention of Stroke and Systemic Embolism in Patients With Atrial Fibrillation in China

PurposeIn China, dabigatran and rivaroxaban are the only approved non–vitamin K antagonist oral anticoagulants for the treatment of atrial fibrillation (AF). The goal of this article was to assess the cost-effectiveness of dabigatran versus rivaroxaban for the prevention of stroke and systemic embolism in Chinese patients with AF from the perspective of the Chinese health care system.MethodsA Markov model was constructed to estimate the cost-effectiveness of dabigatran versus rivaroxaban. Clinical events were modeled for a lifetime horizon, based on clinical efficacy data from indirect treatment comparisons. The weighted average of the most recent prices of these 2 drugs was used as the drug acquisition cost. Other costs, including follow-up costs and event costs, were collected by using a survey from a panel of local experts. Utility inputs (health state utilities, clinical event disutilities, and event history utility) were obtained from published literature. Sensitivity analyses that included scenario analyses and a probabilistic sensitivity analysis were conducted to examine the robustness of the economic model.FindingsOver a lifetime, patients treated with dabigatran experienced fewer ischemic strokes (2.14 dabigatran vs 2.61 rivaroxaban) and fewer intracranial hemorrhage (0.48 vs 0.94) per 100 patient-years. In the base case analysis, dabigatran had an incremental cost of ¥28,128 but with higher life years (10.38 vs 10.14) and quality-adjusted life years (QALYs) (7.95 vs 7.70). The resulting incremental cost-effectiveness ratio of ¥112,910 per QALY gained and net monetary benefit of ¥12,214 versus rivaroxaban showed that dabigatran was a cost-effective alternative to rivaroxaban. Extensive sensitivity analyses indicated that the results were robust over a wide range of inputs. The probabilistic sensitivity analysis indicated that dabigatran was cost-effective in 84.2% of the 10,000 Monte Carlo simulations compared with rivaroxaban.ImplicationsDabigatran reduced the occurrence of clinical events and increased QALYs compared with rivaroxaban. The use of dabigatran for the prevention of stroke and systemic embolism is a cost-effective option compared with rivaroxaban among patients with AF in China.     

Oral Anticoagulation Therapy for Venous Thromboembolism in Norway: Time Trends and Treatment Patterns

PurposeData describing treatment patterns of patients with venous thromboembolism (VTE) patients in Scandinavia are scarce. This study sought to address this scarcity by describing demographic and clinical characteristics, trends in the use of oral anticoagulants (OACs), and treatment patterns in patients treated for VTE in Norway between 2013 and 2017.MethodsUsing data from Norway's nationwide registries, a cohort study included patients newly (after 2008) treated OACs who were diagnosed with VTE between January 2013 and December 2017 and were dispensed an OAC (warfarin, apixaban, rivaroxaban, dabigatran, or edoxaban) within 30 days. Patient characteristics and the percentage of patients with VTE who initiated treatment with each OAC for each calendar year were reported. Initial therapy persistence was assessed using Kaplan-Meier curves and compared between the OAC groups using the log-rank test.FindingsThe comorbidity burden was similar between patients taking warfarin and those taking apixaban but lower among patients taking rivaroxaban. Direct oral anticoagulant (DOAC) use increased from 33.2% to 93.6% during the study period, whereas warfarin use decreased. Persistence was higher in the apixaban cohort compared with the warfarin cohort, with the difference mostly apparent after 6 months, whereas persistence was similar between the patients taking rivaroxaban and those taking warfarin.ImplicationsBetween 2013 and 2017, DOAC use among patients with VTEs increased markedly in Norway, whereas the use of warfarin decreased. Patients taking apixaban had higher persistence compared with those taking warfarin, whereas patients taking warfarin and those taking rivaroxaban had similar persistence. Further studies with longer follow-up are required to examine the use of extended OAC treatment for VTE.     

Phase III studies on novel oral anticoagulants for stroke prevention in atrial fibrillation: a look beyond the excellent results

Summary. In this overview we address the three phase III studies that compared new oral anticoagulants (dabigatran, rivaroxaban and apixaban) with warfarin in the setting of stroke prevention in atrial fibrillation. Strengths and weaknesses of the studies were examined in detail through indirect comparison. We analyze and comment the inclusion and exclusion criteria, the characteristics of randomized patients, the primary efficacy and safety end points and side effects. All new oral anticoagulants resulted in being non‐inferior to vitamin K antagonists in reducing stroke or systemic embolism in patients with atrial fibrillation. Dabigatran 150 mg and apixaban were superior to vitamin K antagonists. Importantly, new oral anticoagulants significantly reduced hemorrhagic stroke in all three studies. Major differences among new oral anticoagulants include the way they are eliminated and side effects. Both dabigatran and apixaban were tested in low‐ to moderate‐risk patients (mean CHADS2 [Congestive heart failure, Hypertension, Age, Diabetes, Stroke] score = 2.1–2.2) whereas rivaroxaban was tested in high‐risk patients (mean CHADS2 score = 3.48) and at variance with dabigatran and apixaban was administered once daily. Apixaban significantly reduced mortality from any cause. The choice of a new oral anticoagulant should take into account these and other differences between the new drugs.     

Anticoagulant-related gastrointestinal bleeding—could this facilitate early detection of benign or malignant gastrointestinal lesions?

Abstract

Introduction. The higher incidence of gastrointestinal (GI) bleeding with the non-vitamin K oral anticoagulants (NOACs) may be related to pre-existing malignancies; diagnostic measures triggered by these bleedings could lead to early detection of these malignancies.

Methods. We retrieved the preferred terms on GI bleeding and GI cancer reported as adverse events (AEs) from phase III studies in patients with atrial fibrillation for each NOAC on ClinicalTrials.gov. We also analyzed the RE-LY trial database.

Results. From ClinicalTrials.gov, AE-GI bleeding incidence was: dabigatran 110 mg b.i.d. (D110: 1.42% versus 1.37%), dabigatran 150 mg b.i.d. (D150: 1.93% versus 1.37%), rivaroxaban (3.52% versus 2.68%), and apixaban (1.93% versus 1.59%), compared with warfarin, respectively. The incidence of AE-GI cancer was similar between the NOACs (D110 [0.79%], D150 [0.61%], rivaroxaban [0.83%], and apixaban [0.69%]), but numerically higher compared with warfarin (0.37%; 0.73%; 0.57%, respectively). In the RE-LY database, the same pattern was seen for dabigatran, with an association between GI bleeding and GI cancer diagnosis.

Conclusion. Anticoagulant-related GI bleeding may represent the unmasking of pre-existing malignancies leading to increased detection of GI cancer. This may be especially in the first month of treatment and could explain the numerically higher numbers of GI malignancies observed with NOACs.     

Approach to the new oral anticoagulants in family practice: Part 1: comparing the options

Objective

To compare key features of the new oral anticoagulants (NOACs)—dabigatran, rivaroxaban, and apixaban—and to address questions that arise when comparing the NOACs.

Sources of information

PubMed was searched for recent (January 2008 to week 32 of 2013) clinical studies relating to NOAC use for stroke prevention in atrial fibrillation (AF) and for the treatment of acute venous thromboembolism (VTE).

Main message

All NOACs are at least as effective as warfarin for stroke prevention in patients with nonvalvular AF, and are at least as safe in terms of bleeding risk according to 3 large trials. Meta-analyses of these trials have shown that, compared with warfarin therapy, NOACs reduced total mortality, cardiovascular mortality, and intracranial bleeding, and there was a trend toward less overall bleeding. Practical advantages of NOACs over warfarin include fixed once- or twice-daily oral dosing without the need for coagulation monitoring, and few known or defined drug or food interactions. Potential drawbacks of NOACs include a risk of bleeding that might be increased in patients older than 75 years, increased major gastrointestinal bleeding with high-dose dabigatran, increased dyspepsia with dabigatran, the lack of a routine laboratory test to reliably measure anticoagulant effect, and the lack of an antidote for reversal. No direct comparisons of NOACs have been made in randomized controlled trials, and the choice of NOAC is influenced by individual patient characteristics, including risk of stroke or VTE, risk of bleeding, and comorbidity (eg, renal dysfunction).

Conclusion

The NOACs represent important alternatives in the management of patients with AF and VTE, especially for patients who have difficulty accessing regular coagulation monitoring. The companion to this article addresses common “what if” questions that arise in the long-term clinical follow-up and management of patients receiving NOACs.     

Fitting the right non-vitamin K antagonist oral anticoagulant to the right patient with non-valvular atrial fibrillation: an evidence-based choice

Atrial fibrillation (AF) is the most prevalent arrhythmia and is associated with an increased risk of ischemic stroke (IS) and systemic embolism (SE). Stroke prevention is a key element for the overall management of AF patients. The non-vitamin K antagonist oral anticoagulants (NOACs), such as dabigatran, rivaroxaban, apixaban and edoxaban, are at least as effective as warfarin in reducing IS/SE with a lower rate of major bleeding. Various analyses from the large Phase III randomized trials demonstrated different efficacy and safety of NOACs in specific subgroups of patients. The randomized trials are supplemented by effectiveness and safety data from real-world observational cohorts following the availability of these drugs for use in everyday clinical practice. Given the clinical heterogeneity of AF patients, the available data from trials and real-world studies allow us to fit the right NOAC to the particular patient’s characteristics, with the aim of optimizing outcomes for the individual patient. This review article aims to provide a summary of the evidence on the performance of NOACs in AF patients with specific clinical characteristics. Evidence-based suggestions are presented to provide a simple and viable strategy for clinicians for the choice of a particular NOAC.

• KEY MESSAGE

• Given the different performance of the new-oral anticoagulants in patients with the different clinical situation, evidence-based choice of fitting the right new-oral anticoagulants to the patients is provided in this review article.

     

Idarucizumab for Intravenous Thrombolysis and Endovascular Thrombectomy in Acute Stroke: A Case Report

BackgroundNon–vitamin K antagonist oral anticoagulants (NOACs), such as dabigatran, are widely used to prevent ischemic stroke in patients with nonvalvular atrial fibrillation. Nonetheless, stroke occurs in 1–2% of patients, and the use of NOACs may increase the bleeding risk for patients who are receiving acute treatment of intravenous thrombolysis (IVT) or endovascular thrombectomy (EVT). Idarucizumab, a monoclonal antibody developed to bind dabigatran, has been proven safe and effective for patients with uncontrolled bleeding or for patients planning to receive emergent procedures. It is now accepted that patients taking dabigatran with recurrent stroke may benefit from IVT after idarucizumab. However, there are limited data regarding idarucizumab use in patients planning to have EVT.Case ReportWe present the case of a male patient taking dabigatran who had a stroke and who was treated with idarucizumab followed by combined IVT and EVT. The patient had immediate recanalization of the occluded vessel and near total recovery of function after 3 months.Why Should an Emergency Physician be Aware of This?Our case report supports the evidence that patients presenting with acute ischemic stroke (AIS) despite being under dabigatran therapy should be evaluated for reversal by idarucizumab which can contribute to the eligibility for IVT as well as EVT. It has also been proved to provide better outcomes for patients with AIS. The availabilities of specific reversal agents for NOACs will probably alter the current management of patients with AIS.     

Non-vitamin K antagonist oral anticoagulants in atrial fibrillation patients with bioprosthetic valves

Introduction: The non-vitamin K antagonist oral anticoagulants (NOACs), which include dabigatran, apixaban, edoxaban and rivaroxaban, are preferred over vitamin K antagonists for stoke prevention in most patients with non-valvular atrial fibrillation. The NOACs are contraindicated in atrial fibrillation patients with rheumatic mitral stenosis or mechanical heart valves. There is evidence that bioprosthetic heart valves are less thrombogenic than mechanical heart valves, but it is unknown whether the risk of thromboembolism in atrial fibrillation patients with bioprosthetic valves differs from that in patients without such valves.

Areas covered: The authors present a review of the efficacy and safety evidence surrounding the use of NOACs for stroke prevention in atrial fibrillation patients with bioprosthetic heart valves.

Expert commentary: While the data is limited, there is no significant difference in thromboembolic, and bleeding outcomes in patients with AF and bioprosthetic heart valves treated with NOAC therapy. Future studies are required before definitive conclusions can be drawn regarding the safety and efficacy of NOAC therapy in AF patients bioprosthetic heart valves.     

Phase III Trials of New Oral Anticoagulants in the Acute Treatment and Secondary Prevention of VTE: Comparison and Critique of Study Methodology and Results

The traditional treatment of venous thromboembolism (VTE) has been use of heparin and vitamin K antagonists (VKA), and although shown to be effective, they have numerous limitations. New oral anticoagulants (NOACs) including direct thrombin (factor IIa) inhibitors (dabigatran) and selective factor Xa inhibitors (rivaroxaban, apixaban and edoxaban) have emerged as promising alternatives with the potential to overcome the limitations of traditional treatments. Clinical trials have been performed with a view to making significant changes to the acute, long-term and extended treatment of VTE. Data are now available on the efficacy and safety, including bleeding rates, of the NOACs in comparison with VKA in the acute treatment and secondary prevention of VTE as well as in comparison with placebo extended VTE treatment. This review compares and contrasts the design and results of the Phase III trials of NOACs in VTE and discusses the implications of the NOACs in terms of treatment strategies in VTE patients.     

Recommendations for the emergency management of complications associated with the new direct oral anticoagulants (DOACs), apixaban, dabigatran and rivaroxaban

Dabigatran, apixaban, and rivaroxaban have been approved for primary and secondary stroke prevention in patients with atrial fibrillation. However, questions have arisen about how to manage emergency situations, such as when thrombolysis would be required for acute ischemic stroke or for the managing intracranial or gastrointestinal bleedings. We summarize the current literature and provide recommendations for the management of these situations. Peak plasma levels of the direct oral anticoagulants (DOACs) apixaban, dabigatran, or rivaroxaban are observed about 2–4 h after intake. Elimination of dabigatran is mainly dependent on renal function. Consequently, if renal function is impaired, there is a risk of drug accumulation that is highest for dabigatran followed by rivaroxaban and then apixaban and thus dosing recommendations are different. To date, no bedside tests are available that reliably assess the anticoagulatory effect of DOACs, nor are specific antidotes available. We recommend performing the following tests if DOAC intake is unknown: dabigatran-associated bleeding risk is minimized or can be neglected if thrombin time, Hemoclot test, or Ecarin clotting time is normal. Apixaban and rivaroxaban effects can be ruled out if findings from the anti-factor Xa activity test are normal. High plasma levels of DOAC are also mostly excluded if PTT and PTZ are normal four or more hours after DOAC intake. However, normal values of global coagulation tests are not sufficient if thrombolysis is indicated for treating acute stroke. The decision for or against thrombolysis is an individual decision; in these cases, thrombolysis use is off-label. In case of bleeding, prothrombin complex concentrates seems to be the most plausible treatment. For severe gastrointestinal bleeding with life-threatening blood loss, the bleeding source needs to be identified and treated by invasive measures. Use of procoagulant drugs (antifibrinolytics) might also be considered. However, there is very limited clinical experience with these products in conjunction with DOAC.     

Implications of new anticoagulants in primary practice

Background: Effective prophylaxis and treatment of thromboembolic disorders remain suboptimal in many healthcare systems, partly owing to limitations of traditional anticoagulants. New oral anticoagulants have been developed and among these, rivaroxaban, apixaban and dabigatran etexilate are in the most advanced stage of clinical development. Method: A literature search using the PubMed and ClinicalTrials.gov databases was performed to identify English‐language publications. The search was performed up to 31 December 2011 with the terms rivaroxaban OR Xarelto, apixaban OR Eliquis and dabigatran OR Pradaxa. Ongoing, completed and published phase III randomised controlled trials were selected as the primary source of information for the clinical development programme of each drug. Results: The new oral agents demonstrate several advantages over traditional anticoagulants, including administration at fixed doses and no requirement for routine coagulation monitoring On the basis of phase III clinical trials, rivaroxaban, apixaban and dabigatran etexilate have been approved in many countries for the prevention of venous thromboembolism after hip and knee replacement surgery. Dabigatran etexilate and rivaroxaban have also been approved for the prevention of stroke and systemic embolism in patients with non‐valvular atrial fibrillation in Europe and the US. In addition, rivaroxaban has been approved in Europe for the treatment of acute deep vein thrombosis and prevention of recurrent venous thromboembolism. Approval of these agents and postapproval monitoring of their safety and efficacy will have implications for primary care. Conclusion: Rivaroxaban, apixaban and dabigatran etexilate offer the possibility of simplified prevention and treatment strategies for thromboembolic disorders in the outpatient setting.     

Evaluation of Oral Anticoagulants for the Extended Treatment of Venous Thromboembolism Using a Mixed-Treatment Comparison,Meta-Analytic Approach

Purpose

Target-specific oral anticoagulants (apixaban, rivaroxaban, and dabigatran) are widely available for the treatment of venous thromboembolism (VTE). Although analyses comparing these agents to placebo or warfarin exist, direct comparisons of these agents for extended VTE treatment have not been conducted. Therefore, this network meta-analysis aimed to evaluate the efficacy and tolerability of VKA and target-specific oral anticoagulants for extended VTE treatment using a mixed-treatment comparison, meta-analytic approach.

Methods

A comprehensive literature search of EMBASE and MEDLINE was conducted to identify relevant randomized, controlled trials published in English between 1960 and November 2013. Eligible studies investigated the extended use (≥6 months) of oral anticoagulants (apixaban, dabigatran, rivaroxaban, and/or warfarin [conventional or low dose]) and placebo in patients with confirmed VTE. Search terms included extension or extended treatment or therapy, venous thromboembolism (or VTE), deep vein thrombosis (or DVT), pulmonary embolism (or PE), and anticoagulant or anticoagulant agent. Key articles were cross-referenced for additional studies. The efficacy end points evaluated were recurrent VTE or death from any cause, DVT, and nonfatal pulmonary embolism PE. Tolerability end points included major bleeding and nonmajor or clinically relevant bleeding. The data were screened, evaluated, and entered into statistical software to generate direct and indirect comparisons of the various anticoagulants across each study. The data are reported as rate ratios and 95% credible intervals.

Findings

Ten trials were analyzed and aggregated, representing data from >14,000 patients. With respect to efficacy end points, no statistically significant between-treatment differences in the composite end point of VTE or death, nonfatal PE, or DVT were found. Major bleeding was significantly greater with warfarin versus apixaban (rate ratio, 4.24; credible interval, 1.28–25.0), and the risk for major bleeding varied somewhat with warfarin and greatly with rivaroxaban. The assessment of nonmajor or clinically relevant bleeding did not identify any meaningful differences between these agents.

Implications

The majority of the data represented in this study were derived from noninferiority trials. In the present meta-analysis, efficacy end points in the extended treatment of VTE with apixaban, dabigatran, rivaroxaban, warfarin (conventional and low dose), and placebo were not significantly different. Elevated bleeding risks were identified with rivaroxaban and warfarin; however, the wide credible intervals with rivaroxaban prevent the interpretation of these increased risks.