Efficacy and safety of the oral direct factor Xa inhibitor apixaban for symptomatic deep vein thrombosis. The Botticelli DVT dose-ranging study

Apixaban Use in Patients with Kidney Impairment: A Review of Pharmacokinetic, Interventional, and Observational Study Data

Chronic kidney disease (CKD) remains a significant global health issue and is a leading cause of mortality worldwide. Patients with CKD have an increased risk of developing atrial fibrillation (AF) and venous thromboembolism (VTE). While direct oral anticoagulants (DOACs) have become a standard of care for anticoagulation (AC) in patients with AF and VTE, the appropriate use of these agents in comorbid kidney impairment warrants detailed discussion. This scientific narrative review summarizes the effectiveness and safety of apixaban use in patients with renal dysfunction by assessing the current published pharmacokinetic, interventional, observational, and guideline data. Apixaban is a highly selective, orally active, direct inhibitor of factor Xa, with well-established pharmacokinetics and consistent clinical outcomes across a broad range of patient populations, including those with kidney impairment. Overall, the scientific literature has shown that apixaban has a favorable clinical efficacy and safety profile compared with vitamin K antagonists for patients with AF or VTE and comorbid kidney impairment. These data support the approved label dosing strategy of apixaban in reducing the risk of stroke/systemic embolism in patients with nonvalvular AF and in treating VTE across all ranges of kidney function. Both clinician experience and knowledge of patient-specific factors may be required in the management of comorbid patients with advanced CKD or those requiring dialysis, as data on these patients are limited.

Oral direct thrombin inhibitors or oral factor Xa inhibitors versus conventional anticoagulants for the treatment of pulmonary embolism

BACKGROUND

Pulmonary embolism (PE) is a potentially life-threatening condition in which a clot can migrate from the deep veins, most commonly in the leg, to the lungs. Conventional treatment of PE used unfractionated heparin (UFH), low molecular weight heparin (LMWH), fondaparinux, and vitamin K antagonists (VKAs). Recently, two forms of direct oral anticoagulants (DOACs) have been developed: oral direct thrombin inhibitors (DTIs) and oral factor Xa inhibitors. DOACs have characteristics that may be favourable to conventional treatment, including oral administration, a predictable effect, no need for frequent monitoring or re-dosing, and few known drug interactions. This review reports the efficacy and safety of these drugs in the long-term treatment of PE (minimum duration of three months). This is an update of a Cochrane Review first published in 2015.  OBJECTIVES: To assess the efficacy and safety of oral DTIs and oral factor Xa inhibitors versus conventional anticoagulants for the long-term treatment of PE.

SEARCH METHODS

The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase and CINAHL databases, the World Health Organization International Clinical Trials Registry Platform and the ClinicalTrials.gov trials registers to 2 March 2022. We checked the reference lists of relevant articles for additional studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) in which people with a PE confirmed by standard imaging techniques were allocated to receive an oral DTI or an oral factor Xa inhibitor compared with a conventional anticoagulant or compared with each other for the long-term treatment of PE (minimum duration three months).

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our primary outcomes were recurrent PE, recurrent venous thromboembolism (VTE), and deep vein thrombosis (DVT). Secondary outcomes were all-cause mortality, major bleeding, and health-related quality of life. We used GRADE to assess the certainty of evidence for each outcome.

MAIN RESULTS

We identified five additional RCTs with 1484 participants for this update. Together with the previously included trials, we have included ten RCTs with a total of 13,073 participants. Two studies investigated an oral DTI (dabigatran) and eight studies investigated oral factor Xa inhibitors (three rivaroxaban, three apixaban, and two edoxaban). The studies were of good methodological quality overall.  Meta-analysis showed no clear difference in the efficacy and safety of oral DTI compared with conventional anticoagulation in preventing recurrent PE (odds ratio (OR) 1.02, 95% confidence interval (CI) 0.50 to 2.04; 2 studies, 1602 participants; moderate-certainty evidence), recurrent VTE (OR 0.93, 95% CI 0.52 to 1.66; 2 studies, 1602 participants; moderate-certainty evidence), DVT (OR 0.79, 95% CI 0.29 to 2.13; 2 studies, 1602 participants; moderate-certainty evidence), and major bleeding (OR 0.50, 95% CI 0.15 to 1.68; 2 studies, 1527 participants; moderate-certainty evidence). We downgraded the certainty of evidence by one level for imprecision due to the low number of events. There was also no clear difference between the oral factor Xa inhibitors and conventional anticoagulation in the prevention of recurrent PE (OR 0.92, 95% CI 0.66 to 1.29; 3 studies, 8186 participants; moderate-certainty evidence), recurrent VTE (OR 0.83, 95% CI 0.66 to 1.03; 8 studies, 11,416 participants; moderate-certainty evidence), DVT (OR 0.77, 95% CI 0.48 to 1.25; 2 studies, 8151 participants; moderate-certainty evidence), all-cause mortality (OR 1.16, 95% CI 0.79 to 1.70; 1 study, 4817 participants; moderate-certainty evidence) and major bleeding (OR 0.71, 95% CI 0.36 to 1.41; 8 studies, 11,447 participants; low-certainty evidence); the heterogeneity for major bleeding was significant (I2 = 79%). We downgraded the certainty of the evidence to moderate and low because of imprecision due to the low number of events and inconsistency due to clinical heterogeneity. None of the included studies measured health-related quality of life.

AUTHORS' CONCLUSIONS

Available evidence shows there is probably little or no difference between DOACs and conventional anticoagulation in the prevention of recurrent PE, recurrent VTE, DVT, all-cause mortality, and major bleeding. The certainty of evidence was moderate or low. Future large clinical trials are required to identify if individual drugs differ in effectiveness and bleeding risk, and to explore effect differences in subgroups, including people with cancer and obesity.

Oral direct thrombin inhibitors or oral factor Xa inhibitors versus conventional anticoagulants for the treatment of deep vein thrombosis

BACKGROUND

Deep vein thrombosis (DVT) is a condition in which a clot forms in the deep veins, most commonly of the leg. It occurs in approximately one in 1000 people. If left untreated, the clot can travel up to the lungs and cause a potentially life-threatening pulmonary embolism (PE). Previously, a DVT was treated with the anticoagulants heparin and vitamin K antagonists. However, two forms of direct oral anticoagulants (DOACs) have been developed: oral direct thrombin inhibitors (DTIs) and oral factor Xa inhibitors, which have characteristics that may be favourable compared to conventional treatment, including oral administration, a predictable effect, lack of frequent monitoring or dose adjustment and few known drug interactions. DOACs are now commonly being used for treating DVT: recent guidelines recommended DOACs over conventional anticoagulants for both DVT and PE treatment. This Cochrane Review was first published in 2015. It was the first systematic review to measure the effectiveness and safety of these drugs in the treatment of DVT. This is an update of the 2015 review.  OBJECTIVES: To assess the effectiveness and safety of oral DTIs and oral factor Xa inhibitors versus conventional anticoagulants for the long-term treatment of DVT.

SEARCH METHODS

The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase and CINAHL databases and the World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov trials registers to 1 March 2022.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) in which people with a DVT, confirmed by standard imaging techniques, were allocated to receive an oral DTI or an oral factor Xa inhibitor compared with conventional anticoagulation or compared with each other for the treatment of DVT.  DATA COLLECTION AND ANALYSIS: We used standard Cochrane methods. Our primary outcomes were recurrent venous thromboembolism (VTE), recurrent DVT and PE. Secondary outcomes included all-cause mortality, major bleeding, post-thrombotic syndrome (PTS) and quality of life (QoL). We used GRADE to assess the certainty of evidence for each outcome.

MAIN RESULTS

We identified 10 new studies with 2950 participants for this update. In total, we included 21 RCTs involving 30,895 participants. Three studies investigated oral DTIs (two dabigatran and one ximelagatran), 17 investigated oral factor Xa inhibitors (eight rivaroxaban, five apixaban and four edoxaban) and one three-arm trial investigated both a DTI (dabigatran) and factor Xa inhibitor (rivaroxaban). Overall, the studies were of good methodological quality. Meta-analysis comparing DTIs to conventional anticoagulation showed no clear difference in the rate of recurrent VTE (odds ratio (OR) 1.17, 95% confidence interval (CI) 0.83 to 1.65; 3 studies, 5994 participants; moderate-certainty evidence), recurrent DVT (OR 1.11, 95% CI 0.74 to 1.66; 3 studies, 5994 participants; moderate-certainty evidence), fatal PE (OR 1.32, 95% CI 0.29 to 6.02; 3 studies, 5994 participants; moderate-certainty evidence), non-fatal PE (OR 1.29, 95% CI 0.64 to 2.59; 3 studies, 5994 participants; moderate-certainty evidence) or all-cause mortality (OR 0.66, 95% CI 0.41 to 1.08; 1 study, 2489 participants; moderate-certainty evidence). DTIs reduced the rate of major bleeding (OR 0.58, 95% CI 0.38 to 0.89; 3 studies, 5994 participants; high-certainty evidence).   For oral factor Xa inhibitors compared with conventional anticoagulation, meta-analysis demonstrated no clear difference in recurrent VTE (OR 0.85, 95% CI 0.71 to 1.01; 13 studies, 17,505 participants; moderate-certainty evidence), recurrent DVT (OR 0.70, 95% CI 0.49 to 1.01; 9 studies, 16,439 participants; moderate-certainty evidence), fatal PE (OR 1.18, 95% CI 0.69 to 2.02; 6 studies, 15,082 participants; moderate-certainty evidence), non-fatal PE (OR 0.93, 95% CI 0.68 to 1.27; 7 studies, 15,166 participants; moderate-certainty evidence) or all-cause mortality (OR 0.87, 95% CI 0.67 to 1.14; 9 studies, 10,770 participants; moderate-certainty evidence). Meta-analysis showed a reduced rate of major bleeding with oral factor Xa inhibitors compared with conventional anticoagulation (OR 0.63, 95% CI 0.45 to 0.89; 17 studies, 18,066 participants; high-certainty evidence).  AUTHORS' CONCLUSIONS: The current review suggests that DOACs may be superior to conventional therapy in terms of safety (major bleeding), and are probably equivalent in terms of efficacy. There is probably little or no difference between DOACs and conventional anticoagulation in the prevention of recurrent VTE, recurrent DVT, pulmonary embolism and all-cause mortality. DOACs reduced the rate of major bleeding compared to conventional anticoagulation. The certainty of evidence was moderate or high.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Severe Bleeding Risks of Direct Oral Anticoagulants in the Prevention and Treatment of Venous Thromboembolism: A Network Meta-Analysis of Randomised Controlled Trials

OBJECTIVE

The aim of this study was to determine the severe bleeding safety of direct oral anticoagulants (DOACs) for the prevention and treatment of venous thromboembolism (VTE).

METHODS

PubMed, EMBASE, Web of Science, and the Cochrane Library databases were searched up to 6 January 2021. The incidence of severe bleeding (major, gastrointestinal [GI], intracranial, and fatal) was investigated. Using frequentist network meta-analysis, interventions that were not compared directly could be compared indirectly by the 95% confidence interval (CI), making the search results more intuitive. Based on surface under the cumulative ranking curves (SUCRA), the relative ranking probability of each group was generated.

RESULTS

Thirty-one randomised controlled trials (76 641 patients) were included. For the treatment of VTE, the risk of major bleeding with apixaban was significantly lower than dabigatran (odds ratio [OR] 2.10, 95% CI 1.07 - 4.12) and edoxaban (OR 2.64, 95% CI 1.36 - 5.15). The safety of the drugs was ranked from highest to lowest as follows: major bleeding: apixaban (SUCRA 98.0), rivaroxaban (SUCRA 69.6), dabigatran (SUCRA 50.7), edoxaban (SUCRA 26.5), and vitamin K antagonists (VKAs; SUCRA 5.1); GI bleeding: apixaban (SUCRA 80.7), rivaroxaban (SUCRA 66.8), edoxaban (SUCRA 62.3), VKAs (SUCRA 34.4), and dabigatran (SUCRA 5.8); intracranial bleeding: rivaroxaban (SUCRA 74.4), edoxaban (SUCRA 70.4), dabigatran (SUCRA 58.2), apixaban (SUCRA 44.4), and VKAs (SUCRA 5.6); fatal bleeding: edoxaban (SUCRA 82.7), rivaroxaban (SUCRA 59.2), dabigatran (SUCRA 48.6), apixaban (SUCRA 43.0), and VKAs (SUCRA 16.3). For the prevention of VTE, the risk of major bleeding with apixaban was significantly lower than rivaroxaban (OR 2.14, 95% CI 1.02 - 4.52). Among the four types of bleeding, apixaban had the lowest bleeding risk among DOACs (major bleeding: SUCRA 81.6; GI bleeding: SUCRA 75.4; intracranial bleeding: SUCRA 64.1; fatal bleeding: SUCRA 73.6).

CONCLUSIONS

For the treatment of VTE, in terms of major bleeding and GI bleeding, apixaban had the lowest bleeding risk; in terms of intracranial bleeding, rivaroxaban had the lowest bleeding risk; in terms of fatal bleeding, edoxaban had the lowest bleeding risk. For the prevention of VTE, apixaban had the lowest bleeding risk.

Thromboprophylaxis across orthopaedic surgery: Bibliometric analysis of the most cited articles

PURPOSE

One of the most common adverse events after orthopaedic surgery, with a potential for subsequent serious morbidity and mortality is venous thromboembolism (VTE). Bibliometric analysis has been performed regarding many topics and across orthopaedics. As DVT prophylaxis is a major component of both orthopaedic surgery considerations and research, a bibliometric analysis in this area would prove beneficial in not only in understanding the research done in the field thus far, but would also direct future research efforts.

METHODS

The Web of Science (WoS) database from the Institute of Scientific Information (ISI) was used to compile articles for bibliometric analysis using Boolean search: ((Orthopaedic∗ OR Orthopaedic∗) AND (thromboprophylaxis OR Thromboembolism OR Deep vein thrombosis OR thrombus OR embolism OR anticoagulation OR Embolus OR prophylaxis)).

RESULTS

The Top 100 cited articles included in the final list generated a total of 21,099 citations. The highest cited article was Prevention of venous thromboembolism by Geerts et al. published in Chest, which had a total of 2802 on WoS, and a calculated citation density of 215.54 of citations/years since publication. Comparing the overall citation against the year of publication there was a slight positive trend favoring more recent publications (R-value: 0.142; adjusted R-squared: 0.01; p = 0.16). Analysis of an articles Level of Evidence (LOE), 17 were grade with a level of I.

CONCLUSIONS

Orthopaedic thromboprophylaxis is an ever-changing field that is at the forefront of orthopaedic literature. The significant trend favoring high quality research within orthopaedic thromboprophylaxis demonstrates the importance of this topic and there was a need for a guide to best understand the evolution of DVT prophylaxis.

Twice- or Once-Daily Dosing of Direct Oral Anticoagulants, a systematic review and meta-analysis

AIM

The direct oral anticoagulants (DOAC) have similar half-lives, but the dosing regimen varies between once daily (QD) or twice daily (BID). For some prescribers, the QD regimen improves compliance. Others prefer BID regimens to promote better stability of plasma concentrations, particularly in the event of missed doses. Limited level of evidence provides guidance about the best treatment strategy. The purpose of this study was to compare the treatment effect of QD vs. BID administration of DOACs in major orthopedic surgery (MOS), non-valvular atrial fibrillation (NVAF), venous thromboembolism (VTE), and acute coronary syndrome (ACS).

METHODS

We conducted a systematic review up to April 2020. We included phase II clinical trials comparing DOAC QD vs BID with same daily dose. We extracted data for the occurrence of major thrombosis (proximal deep vein thrombosis, pulmonary embolism, myocardial infarction, ischemic stroke) and major hemorrhage (ISTH criteria and recommendations of the European Medicines Agency for surgical patients). Relative risks (RR) were combined using a fixed and random effects weighted meta-analysis.

RESULTS

Twelve randomized, controlled, phase II trials were included (10,716 patients), representing 24 dosing regimen comparisons of apixaban, darexaban, edoxaban, rivaroxaban, letaxaban, and dabigatran. There was no difference for major thrombotic event (RR_BID/QD = 1.06, 95%IC 0.86-1.30) nor for major bleeding (RR_BID/QD = 1.02, 95%IC 0.84-1.23) between the BID vs QD regimens, without heterogeneity (I² = 0%).

CONCLUSION

Our study does not support a global difference in term of efficacy and safety of the BID and QD regimens of DOAC in MOS, NVAF, VTE and ACS.

American Society of Hematology 2020 guidelines for management of venous thromboembolism: treatment of deep vein thrombosis and pulmonary embolism

BACKGROUND

Venous thromboembolism (VTE), which includes deep vein thrombosis (DVT) and pulmonary embolism (PE), occurs in ∼1 to 2 individuals per 1000 each year, corresponding to ∼300 000 to 600 000 events in the United States annually.

OBJECTIVE

These evidence-based guidelines from the American Society of Hematology (ASH) intend to support patients, clinicians, and others in decisions about treatment of VTE.

METHODS

ASH formed a multidisciplinary guideline panel balanced to minimize potential bias from conflicts of interest. The McMaster University GRADE Centre supported the guideline development process, including updating or performing systematic evidence reviews. The panel prioritized clinical questions and outcomes according to their importance for clinicians and adult patients. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used to assess evidence and make recommendations, which were subject to public comment.

RESULTS

The panel agreed on 28 recommendations for the initial management of VTE, primary treatment, secondary prevention, and treatment of recurrent VTE events.

CONCLUSIONS

Strong recommendations include the use of thrombolytic therapy for patients with PE and hemodynamic compromise, use of an international normalized ratio (INR) range of 2.0 to 3.0 over a lower INR range for patients with VTE who use a vitamin K antagonist (VKA) for secondary prevention, and use of indefinite anticoagulation for patients with recurrent unprovoked VTE. Conditional recommendations include the preference for home treatment over hospital-based treatment for uncomplicated DVT and PE at low risk for complications and a preference for direct oral anticoagulants over VKA for primary treatment of VTE.

[Evaluation of direct oral anticoagulants (DOACs) prescriptions in geriatric hospital over 3 years]

INTRODUCTION

Direct oral anticoagulants (DOACs) are an attractive choice for patients in need of anticoagulant therapy, but available data on their specific use in real life conditions in elderly patients are limited. The purpose of this study is to describe the characteristics and evolution of the prescriptions in geriatric hospital.

PATIENTS AND METHODS

The prescriptions of patients treated with DOACs in two university geriatric hospitals were analyzed retrospectively over 3 years. Co-treatment and hemorrhagic and thrombotic complications were studied.

RESULTS

A total of 399 patients were included, including 10 in 2015, 110 in 2016 and 279 in 2017. The average age was 85 years old, 40% of patients had a weight of less than 60kg, and more than 50% had an estimated creatinine clearance of less than 50mL/min. The most common indication was atrial fibrillation in 85%. In 32% of cases, the dosage of DOACs was not adapted to official recommendations. Underdosages accounted for approximately 60% of dosage errors. Twelve patients (3% of the cohort) had a thrombotic event under DOACs, associated with an underdosing in 50% of them. 41 patients, or 10% of the cohort, had a hemorrhagic event under DOACs, with 12 patients (29%) having a pharmacologic risk factor (10 overdoses and 2 drug interactions).

CONCLUSION

The prescription of DOACs in elderly patients has increased considerably in recent years. However, dosing errors remain frequent (overdoses as underdoses), associated with hemorrhagic or thrombotic events. Similarly, drug interactions should be known as they are a risk factor for avoidable under- or overdose. Improving prescriptions of DOACs in geriatrics needs to respect the rules of good practice, to regularly reassess renal function, and to transmit observations of adverse effects to pharmacovigilance centers.

Comparative Effects Between Direct Oral Anticoagulants for Acute Venous Thromboembolism: Indirect Comparison From Randomized Controlled Trials

Background: There is no direct comparison from clinical trials amongst the direct oral anticoagulants (DOACs) in patients with acute venous thromboembolism (VTE), leaving an evidence gap in decision-making regarding the choice of a DOAC.

Methods: We performed a systematic review for an indirect comparison from randomized controlled trials (RCTs) for comparative effects amongst DOACs in the patients with acute VTE.

Results: A total of 16 RCTs were included for analyses, among which three for dabigatran (n = 7,963 patients), six rivaroxaban (n = 17,935), five apixaban (n = 12,823), and two edoxaban (n = 9,286). There was no significant difference in risk of recurrent VTE (evidence quality: low) and major bleeding (evidence quality: very low) for treatment effects between the four DOACs. Albeit non-significantly, apixaban seemed to have a lowest risk of major bleeding while rivaroxaban had a smallest risk of VTE. Although in general all the included trials were comparable, data from the included trials indicated that the assumption of transitivity may be challenged. Further methodological research including simulation studies, using a net-benefit or benefit-harm approach, running ranking probability analysis, and developing decision aids with machine-learning may be a worthwhile endeavor to help with the choice of DOACs in patients with acute VTE.

Conclusions: To conclude, based on results from the indirect comparison no significant difference in the efficacy and safety was found among the DOACs in patients with acute VTE. More evidence from direct comparative trials is needed to further inform the choice of DOACs in patients with acute VTE.

Risk of Major Gastrointestinal Bleeding With New vs Conventional Oral Anticoagulants: A Systematic Review and Meta-analysis

BACKGROUND & AIMS

There is controversy over whether use of non-vitamin K antagonist oral anticoagulants (NOACs) associates with increased risk of major gastrointestinal bleeding (GIB) compared with conventional therapies (such as vitamin K antagonists or anti-platelet agents). We performed a systematic review and meta-analysis of data from randomized controlled trials and high-quality real-world studies.

METHODS

We performed a systematic search of the MEDLINE, EMBASE, Cochrane Library, and ClinicalTrials.gov Website databases (through Oct 12, 2018) for randomized controlled trials and high-quality real-world studies that reported major GIB events in patients given NOACs or conventional therapy. Relative risks (RRs) for randomized controlled trials and adjusted hazard ratios (aHRs) for real-world studies were calculated separately using random-effects models.

RESULTS

We analyzed data from 43 randomized controlled trials (183,752 patients) and 41 real-world studies (1,879,428 patients). The pooled major rates of GIB for patients on NOACs (1.19%) vs conventional treatment (0.92%) did not differ significantly (RR from randomized controlled trials, 1.09; 95% CI, 0.91-1.31 and aHR from real-world studies, 1.02; 95% CI, 0.94-1.10; P_interaction=.52). Rivaroxaban, but not other NOACs, was associated with an increased risk for major GIB (RR from randomized controlled trials, 1.39; 95% CI, 1.17-1.65 and aHR from real-world studies, 1.14; 95% CI, 1.04-1.23; P_interaction = .06). Analyses of subgroups, such as patients with different indications, dosage, or follow-up time, did not significantly affect results. Meta-regression analysis failed to detect any potential confounding to impact the primacy outcome.

CONCLUSIONS

In a systematic review and meta-analysis of data from randomized controlled trials and real-world studies, we confirmed that there is no significant difference in risk of major GIB between patients receiving NOACs vs conventional treatment. Rivaroxaban users had a 39% increase in risk for major GIB.

Direct Oral Anticoagulants and Travel-related Venous Thromboembolism

Travel- related thromboembolism reflects the relationship between venous thromboembolism (VTE) and long-haul flights. Although this condition is rare, it may cause significant morbidity and mortality. Therefore, travelers should be evaluated for the risks for thrombosis. Travel physicians should employ a clinical risk score and select in vestigations, prophylaxis, and treatment that are appropriate for each individual. This review summarizes current VTE clinical risk scores and patient management from various reliable guidelines. We summarized 16 reliable publications for reviewing data. Direct oral anticoagulants (DOACs) are currently the standard treatment for VTE and a prophylactic measure for VTE in orthopedic surgery. Compared with a vitamin K antagonist (VKA), DOACs show better safety and similar efficacy without the need for monitoring, and have fewer food/drug interactions. Inferred from the data on general VTE, DOACs may be used to treat travel-related VTE. Although the data are lacking, DOACs may be used off-label as VTE prophylax is. Before using DOACs, physicians must know the pharmacology of the drugs well and should realize that the availability of antidotes for bleeding complications is limited.

Use of Direct Oral Anticoagulants in Patients with Cancer: Practical Considerations for the Management of Patients with Nausea or Vomiting

Direct oral anticoagulants (DOACs) have proven efficacy and safety and are approved for use in the prevention and treatment of thromboembolic events in patients with venous thromboembolism (VTE) and those with atrial fibrillation (AF). There is no clear guidance on the use of DOACs in the significant proportion of these patients who have or will develop concomitant cancer. The occurrence of nausea and vomiting in these patients, despite implementation of guideline-recommended antiemetic strategies, is a particular concern because it may affect oral drug intake and consequently outcomes with anticoagulation therapy.Here, we review recent data on the incidence and management of cancer-associated nausea and vomiting and the current evidence and guidance relating to the use of DOACs in patients with cancer. On the basis of this evidence, an international working group of experts in the fields of cancer-associated thrombosis/hemostasis, hematology, and oncology discussed key issues related to the use of DOACs in patients with VTE or AF and cancer who are at risk of nausea and vomiting and developed some consensus recommendations. We present these consensus recommendations, which outline strategies for the use and management of anticoagulants, including DOACs, in patients with VTE or AF and cancer for whom oral drug intake may pose challenges. Guidance is provided on managing patients with gastrointestinal obstruction or nausea and vomiting that is caused by cancer treatments or other cancer-related factors.The recommendations outlined in this review provide a useful reference for health care professionals and will help to improve the management of anticoagulation in patients with VTE or AF and cancer.

IMPLICATIONS FOR PRACTICE

Direct oral anticoagulants (DOACs) offer several advantages over traditional anticoagulants, including ease of administration and the lack of need for routine monitoring. However, the management of patients with an indication for anticoagulation and concomitant cancer, who are at high risk of thromboembolic events, presents several challenges for administering oral therapies, particularly with regard to the risk of nausea and vomiting. In the absence of robust data from randomized trials and specific guidelines, consensus recommendations were developed for healthcare professionals regarding the use of DOACs in patients with cancer, with a focus on the management of patients who are at risk of nausea and vomiting.

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.

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.

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.

Darexaban (YM150) versus enoxaparin for the prevention of venous thromboembolism after total hip arthroplasty: a randomised phase IIb dose confirmation study (ONYX-3)

This double-blind, double-dummy, randomised, phase IIb study (NCT00902928) evaluated different dosing regimens of darexaban compared with enoxaparin (randomised 1:1:1:1:1 to 15 mg twice daily [bid], 30 mg once daily [qd], 30 mg bid or 60 mg qd or enoxaparin 40 mg qd) in patients undergoing elective total hip arthroplasty. Patients, investigators, pharmacists and sponsor were all blinded to treatment allocation. Darexaban administration started 6-10 hours (h) post-surgery. Enoxaparin 40 mg qd administration started 12 ± 2 h before surgery. Treatment continued for 35 days. Bilateral venography was performed on Day 10 ± 2. The primary efficacy outcome was total VTEs (composite of proximal/distal deep-vein thrombosis, pulmonary embolism) or death, at Day 12. Total VTE rates were similar across all groups. There was no apparent difference in efficacy between onceand twice-daily darexaban (odds ratio [OR] 1.00; 95% confidence interval [CI] 0.71–1.42; p=0.988), or total daily dose (30 mg/day vs 60 mg/day; OR 0.81; 95% CI 0.57–1.15; p=0.244). There was no significant difference in major and/or clinically relevant non-major bleeding between darexaban qd or bid, or between total daily doses of 30 mg or 60 mg, and also for any dosing regimen of darexaban vs enoxaparin. Darexaban was well tolerated, without signs of liver toxicity. In conclusion, darexaban, administered qd or bid, and at total daily doses of 30 mg or 60 mg, appears to be effective for VTE prevention and was well tolerated. Data suggest no significant differences between a once- or twice-daily dosing regimen.

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.

Population Pharmacokinetics, Pharmacodynamics, and Exploratory Exposure-Response Analyses of Apixaban in Subjects Treated for Venous Thromboembolism

Apixaban is approved for treatment of venous thromboembolism (VTE) and prevention of recurrence. Population pharmacokinetics, pharmacokinetics-pharmacodynamics (anti-FXa activity), and exposure-response (binary bleeding and thromboembolic endpoints) of apixaban in VTE treatment subjects were characterized using data from phase I-III studies. Apixaban pharmacokinetics were adequately characterized by a two-compartment model with first-order absorption and elimination. Age, sex, and Asian race had less than 25% impact on exposure, while subjects with severe renal impairment were predicted to have 56% higher exposure than the reference subject (60-year-old non-Asian male weighing 85 kg with creatinine clearance of 100 mL/min). The relationship between apixaban concentration and anti-FXa activity was described by a linear model with a slope estimate of 0.0159 IU/ng. The number of subjects with either a bleeding or thromboembolic event was small, and no statistically significant relationship between apixaban exposure and clinical endpoints could be discerned with a logistic regression analysis.

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.

Apixaban: A Review in Venous Thromboembolism

Apixaban (Eliquis^®) is an oral, direct factor Xa inhibitor that is available for use in the treatment and secondary prevention of venous thromboembolism (VTE). Like other direct oral anticoagulants (DOACs), apixaban has generally predictable pharmacological properties and does not require routine anticoagulation monitoring. In large phase III trials, oral apixaban was noninferior to subcutaneous enoxaparin sodium overlapped with and followed by oral warfarin (enoxaparin/warfarin) in the treatment of adults with acute VTE over 6 months with regard to the incidence of recurrent VTE or VTE-related death (AMPLIFY), and was significantly more effective than placebo in the prevention of recurrent VTE or all-cause mortality over 12 months in patients who had completed 6-12 months' anticoagulation treatment for VTE (AMPLIFY-EXT). Apixaban was generally well tolerated in these trials; the risks of major bleeding and the composite endpoint of major or clinically relevant nonmajor (CRNM) bleeding with apixaban were significantly lower than enoxaparin/warfarin in AMPLIFY and not significantly different from that of placebo in AMPLIFY-EXT. Similarly, in Japanese adults with acute VTE (AMPLIFY-J), apixaban was associated with a significantly lower risk of major or CRNM bleeding than unfractionated heparin plus warfarin, and no cases of recurrent VTE or VTE-related death over 24 weeks. Thus, apixaban is useful therapeutic alternative for the management of adults with VTE.

The effect of apixaban on the pharmacokinetics of digoxin and atenolol in healthy subjects

Purpose

Apixaban is often coadministered with treatments for cardiovascular comorbidities, which may lead to unintended drug–drug interactions (DDIs). The effects of apixaban on pharmacokinetics (PK) of multidose Lanoxin^® (digoxin) and single-dose Tenormin^® (atenolol) and the effects of single-dose atenolol on apixaban PK in healthy subjects were investigated in two Phase 1 studies.

Patients and methods

The digoxin DDI study was an open-label, multidose, two-treatment, single-sequence study in which subjects received digoxin 0.25 mg q6h on day 1, then once daily on days 2–10, followed by apixaban 20 mg and digoxin 0.25 mg once daily on days 11–20. The atenolol DDI study was an open-label, single-dose, randomized, three-period, three-treatment, crossover study in which subjects received a single oral dose of apixaban 10 mg, atenolol 100 mg, or apixaban 10 mg plus atenolol 100 mg. The 90% confidence intervals (CIs) for the ratios of geometric means of peak plasma concentration (C_max) and area under the concentration–time curve (AUC_tau), with and without apixaban were calculated. Absence of effect was concluded if the point estimates and 90% CI were within the equivalence interval of 80%–125% (digoxin) or 70%–143% (atenolol). A similar analysis was performed to assess the effect of atenolol on apixaban.

Results

Apixaban had no clinically relevant effect on the PK of either atenolol or digoxin: point estimates and 90% CI for both digoxin and atenolol C_max and AUC were entirely within their respective no-effect intervals. Apixaban C_max and AUC_inf were slightly decreased (ie, 18% and 15% lower, respectively) following atenolol coadministration. No serious or major bleeding-related adverse events were reported during either study.

Conclusion

Apixaban had no effect on the PK of digoxin and there was no clinically relevant interaction between apixaban and atenolol. Coadministration of digoxin or atenolol with apixaban in healthy subjects was generally well tolerated.

Venous Thromboembolism in Cancer: An Update of Treatment and Prevention in the Era of Newer Anticoagulants

Cancer patients are at major risk of developing venous thromboembolism (VTE), resulting in increased morbidity and economic burden. While a number of theories try to explain its pathophysiology, its risk stratification can be broadly done in cancer-related, treatment–related, and patient-related factors. Studies report the prophylactic use of thrombolytic agents to be safe and effective in decreasing VTE-related mortality/morbidity especially in postoperative cancer patients. Recent data also suggest the prophylactic use of low molecular weight Heparins (LMWHs) and Warfarin to be effective in reducing VTEs related to long-term central venous catheter use. In a double-blind, multicenter trial, a new ultra-LMWH Semuloparin has shown to be efficacious in preventing chemotherapy-associated VTE’s along with other drugs, such as Certoparin and Nadoparin. LMWHs are reported to be very useful in preventing recurrent VTEs in advanced cancers and should be preferred over full dose Warfarin. However, their long-term safety beyond 6 months has not been established yet. Furthermore, this paper discusses the safety and efficacy of different drugs used in the treatment and prevention of recurrent VTEs, including Bemiparin, Semuloparin, oral direct thrombin inhibitors, parenteral and direct oral factor Xa inhibitors.

Direct Oral Anticoagulants for the Management of Thromboembolic Disorders

Anticoagulation therapy is central to the management of thromboembolic disorders, and the use of direct oral anticoagulants offers several advantages over standard therapy with parenteral heparins and vitamin K antagonists. In phase III clinical trials, the direct oral anticoagulants (given once or twice daily) all demonstrated favorable benefit–risk profiles compared with conventional standard therapy for the treatment and secondary prevention of venous thromboembolism and for stroke prevention in patients with nonvalvular atrial fibrillation. In clinical practice, many factors may influence overall clinical outcomes in patients receiving anticoagulant therapy, including adherence and persistence to the prescribed therapy, which becomes particularly important during long-term therapy. When choosing an anticoagulant for an individual patient, the pharmacological and clinical profile of the anticoagulant, its dosing regimen, and the patient’s clinical characteristics (eg, renal function and comorbidities) and preferences should be considered. This review examines the rationale for and clinical evidence of the selected dosing regimens of the direct oral anticoagulants for the treatment of venous thromboembolism and stroke prevention in nonvalvular atrial fibrillation. The potential influence of dosing strategies (eg, once- or twice-daily dosing) and other factors on patient adherence and therapy persistence are also discussed.

Evidence-Based Development and Rationale for Once-Daily Rivaroxaban Dosing Regimens Across Multiple Indications

Background:

Rivaroxaban, a direct factor Xa inhibitor, has been developed to meet clinical needs in a broad range of indications in adults: prevention of venous thromboembolism after elective hip or knee replacement surgery, treatment and secondary prevention of venous thromboembolism, prevention of stroke and systemic embolism in patients with nonvalvular atrial fibrillation having one or more risk factors, and in Europe, prevention of atherothrombotic events after an acute coronary syndrome in patients with elevated cardiac biomarkers. However, the precise dose and regimen vary with the indication, leading to this effort to provide clarity concerning the appropriate use of rivaroxaban. This article reviews the clinical development program for rivaroxaban and summarizes the evidence for each approved, indication-specific dose regimen.

Results:

Although initially investigated for twice-daily dosing, early observations, including the finding that the pharmacodynamic effects of rivaroxaban last longer than the elimination half-life, suggested that once-daily dosing might be attainable and effective. These observations were evaluated within the extensive phase II program, which, together with pharmacology studies, provides the evidence underpinning the selection of once-daily regimens for most, but not all, of the approved clinical indications for rivaroxaban.

Conclusion:

The evidence for each dosing regimen demonstrates that although pharmacology studies are of paramount importance, dose regimens must be subjected to careful empirical validation. Once-daily dosing was shown to be clinically appropriate for most rivaroxaban indications. Furthermore, a “one size fits all” approach to dosing frequency is unlikely to result in a regimen that yields optimal patient outcomes across different indications.

Effects of age and sex on the single-dose pharmacokinetics and pharmacodynamics of apixaban

BACKGROUND AND OBJECTIVES

The effects of age and sex on apixaban pharmacokinetics and pharmacodynamics were studied.

METHODS

This was an open-label, single-dose, 2 × 2 factorial study. Healthy young (aged 18-40 years) and elderly (aged ≥ 65 years) male and female subjects received a single oral 20 mg dose of apixaban. Blood and urine samples were collected for pharmacokinetic and pharmacodynamic (blood only) analyses. Subjects were monitored for adverse events throughout the study.

RESULTS

Seventy-nine subjects were enrolled into four groups: young males (n = 20), elderly males (n = 20), young females (n = 20) and elderly females (n = 19). Age did not affect the maximum observed plasma concentration (C max). The mean area under the concentration-time curve from time zero extrapolated to infinite time (AUC∞) was 32% greater in elderly subjects than in young subjects. The mean C max and AUC∞ values were 18 and 15% higher, respectively, in females than in males. The time course of the mean international normalized ratio (INR), modified prothrombin time (mPT) and anti-Xa activity tracked the apixaban concentration-time curve. All three pharmacodynamic measures exhibited a positive linear correlation with the plasma apixaban concentration. Differences in the mean INR, mPT and anti-Xa activity between age and sex groups were small (<15% at the maximum mean values) and were generally related to pharmacokinetic differences. However, anti-Xa activity demonstrated less variability than the INR or mPT, and may have utility as a bioassay for apixaban. Apixaban was well tolerated, with no serious adverse events.

CONCLUSION

There were no clinically meaningful age- or sex-related differences in the pharmacokinetics and pharmacodynamics of apixaban that would require dose modification on the basis of age or sex alone.

Reducing the risk of venous thromboembolism using apixaban - patient perspectives and considerations. Should more attention be given to females?

BACKGROUND

New oral anticoagulant agents, such as apixaban, rivaroxaban, dabigatran, or endoxaban, have recently become for patients an alternative option to conventional treatment in the therapy of venous thromboembolism (VTE). Thus, we aimed to review the available information on adverse events (AEs) of apixaban compared to conventional therapy (heparin or vitamin K antagonists) in randomized controlled trials (RCTs) on patients treated for VTE, with a particular attention to sex subgroups.

METHODS

An electronic search in MEDLINE and Embase was performed by using the keywords "apixaban" and "venous thromboembolism". All RCTs focused on apixaban in the treatment and prevention of VTE were evaluated for the presence of AEs. AEs were classified as serious, bleeding, and cause of discontinuation. Moreover, we also searched by using the keywords "gender" and "venous thromboembolism" and "anticoagulants".

RESULTS

Considering all subjects enrolled in the eleven RCTs as a whole to investigate the occurrence of AEs, we extrapolated an events/subjects rate of 57.8% for AEs (6,445/11,144), 7.7% for serious AEs (975/12,647), 9.1% for bleeding events (1,229/13,454), and 3.2% for discontinuation of apixaban (421/13,039). The percentage of AEs was lower in subjects treated with apixaban than in those treated with conventional VTE therapy (53% vs 56.3%, respectively). However, only one study provided data on separate analysis by sex of either efficacy or safety of apixaban.

CONCLUSION

Under the patient's perspective, apixaban could represent a good choice in the treatment of VTE, due to its pharmacological, economical, and safety profile. These positive aspects are certainly present in both sexes, since the available studies include a correct percentage of women, but data with separate analyses by sex are extremely limited. Future clinical trials should include in their results on clinical impact and outcomes a stratification by sex, and studies aimed to evaluate possible sex-related differences for these drugs should be strongly encouraged.

Comparison of the Novel Oral Anticoagulants Apixaban, Dabigatran, Edoxaban, and Rivaroxaban in the Initial and Long-Term Treatment and Prevention of Venous Thromboembolism: Systematic Review and Network Meta-Analysis

Background

Anticoagulation with low molecular weight heparin and vitamin K antagonists is the current standard of care (SOC) for venous thromboembolism (VTE) treatment and prevention. Although novel oral anti-coagulants (NOACs) have been compared with SOC in this indication, no head-to-head randomised controlled trials (RCTs) have directly compared NOACs. A systematic review and network meta-analysis (NMA) were conducted to compare the efficacy and safety of NOACs for the initial and long-term treatment of VTE.

Methods

Electronic databases (accessed July 2014) were systematically searched to identify RCTs evaluating apixaban, dabigatran, edoxaban, and rivaroxaban versus SOC. Eligible patients included adults with an objectively confirmed deep vein thrombosis (DVT), pulmonary embolism (PE) or both. A fixed-effect Bayesian NMA was conducted for outcomes of interest, and results were presented as relative risks (RR) and 95% credible intervals (Crl).

Results

Six Phase III RCTs met criteria for inclusion: apixaban (one RCT; n = 5,395); rivaroxaban (two RCTs; n = 3,423/4,832); dabigatran (two RCTs; n = 2,539/2,568); edoxaban (one RCT; n = 8,240). There were no statistically significant differences between the NOACs with regard to the risk of ‘VTE and VTE-related death. Apixaban treatment was associated with the most favourable safety profile of the NOACs, showing a statistically significantly reduced risk of ‘major or clinically relevant non-major (CRNM) bleed’ compared with rivaroxaban (0.47 [0.36, 0.61]), dabigatran (0.69 [0.51, 0.94]), and edoxaban (0.54 [0.41, 0.69]). Dabigatran was also associated with a significantly lower risk of ‘major or CRNM bleed’ compared with rivaroxaban (0.68 [0.53, 0.87]) and edoxaban (0.77 [0.60, 0.99]).

Conclusions

Indirect comparisons showed statistically similar reductions in the risk of ‘VTE or VTE-related death for all NOACs. In contrast, reductions in ‘major or CRNM bleed’ for initial/long-term treatment were significantly better with apixaban compared with all other NOACs, and with dabigatran compared with rivaroxaban and edoxaban. Results from the current analysis indicate that the NOACs offer clinical benefit over conventional therapy while highlighting relative differences in their bleeding profile.

Early time courses of recurrent thromboembolism and bleeding during apixaban or enoxaparin/warfarin therapy. A sub-analysis of the AMPLIFY trial

Risks of recurrence and bleeding are highest during the first weeks of anticoagulant therapy for venous thromboembolism (VTE). We therefore examined the early time course of recurrence and major bleeding in a pre-specified sub-analysis of the AMPLIFY trial, a randomised, double-blind, six-month comparison of oral apixaban with conventional therapy (enoxaparin followed by warfarin) in 5,395 patients with symptomatic proximal deep-vein thrombosis or pulmonary embolism. Early events were of particular interest because apixaban was given without initial heparin treatment. The primary efficacy and safety outcomes were the incidences of the adjudicated composite of recurrent symptomatic VTE or death related to VTE, and of adjudicated major bleeding, respectively. This analysis reports on recurrence and bleeding after 7, 21, and 90 days of therapy, in addition to the previously reported end-of-study results. These were the times specified before statistical analysis. Recurrent VTE after 7, 21, and 90 days, and six months had occurred in 18 (0.7%), 29 (1.1%), 46 (1.8%), and 59 patients (2.3%), respectively, given apixaban, and in 23 (0.9%), 35 (1.3%), 58 (2.2%), and 71 patients (2.7%), respectively, given conventional therapy. Major bleeding had occurred during these time intervals in 3 (0.1%), 5 (0.2%), 11 (0.4%), and 15 patients (0.6%), respectively, who received apixaban, and in 16 (0.6%), 26 (1.0%), 38 (1.4%), and 49 patients (1.8%), respectively, given conventional therapy. Efficacy of apixaban was non-inferior at each time point, with no excess of early recurrences. The reduced bleeding risk associated with apixaban began early during the course of treatment.

Oral direct thrombin inhibitors or oral factor Xa inhibitors for the treatment of pulmonary embolism

BACKGROUND

Pulmonary embolism is a potentially life-threatening condition in which a clot can travel from the deep veins, most commonly in the leg, up to the lungs. Previously, a pulmonary embolism was treated with the anticoagulants heparin and vitamin K antagonists. Recently, however, two forms of direct oral anticoagulants (DOACs) have been developed: oral direct thrombin inhibitors (DTI) and oral factor Xa inhibitors. The new drugs have characteristics that may be favourable over conventional treatment, including oral administration, a predictable effect, lack of frequent monitoring or re-dosing and few known drug interactions. To date, no Cochrane review has measured the effectiveness and safety of these drugs in the long-term treatment (minimum duration of three months) of pulmonary embolism.

OBJECTIVES

To assess the effectiveness of oral DTIs and oral factor Xa inhibitors for the long-term treatment of pulmonary embolism.

SEARCH METHODS

The Cochrane Vascular Trials Search Co-ordinator searched the Specialised Register (last searched January 2015) and the Cochrane Register of Studies (last searched January 2015). Clinical trials databases were also searched for details of ongoing or unpublished studies. We searched the reference lists of relevant articles retrieved by electronic searches for additional citations.

SELECTION CRITERIA

We included randomised controlled trials in which patients with a pulmonary embolism confirmed by standard imaging techniques were allocated to receive an oral DTI or an oral factor Xa inhibitor for the long-term (minimum duration three months) treatment of pulmonary embolism.

DATA COLLECTION AND ANALYSIS

Two review authors (LR, JM) independently extracted the data and assessed the risk of bias in the trials. Any disagreements were resolved by discussion with the third author (PK). We used meta-analyses when we considered heterogeneity low. The two primary outcomes were recurrent venous thromboembolism and pulmonary embolism. Other outcomes included all-cause mortality and major bleeding. We calculated all outcomes using an odds ratio (OR) with a 95% confidence interval (CI).

MAIN RESULTS

We included five randomised controlled trials with a total of 7897 participants. Two studies tested oral DTIs (dabigatran) and three studies tested oral factor Xa inhibitors (one rivaroxaban, one edoxaban and one apixaban).Analysis showed no difference in the effectiveness of oral DTIs and standard anticoagulation in preventing recurrent pulmonary embolism (OR 1.02, 95% CI 0.50 to 2.04; two studies; 1602 participants; high quality evidence), recurrent venous thromboembolism (OR 0.93, 95% CI 0.52 to 1.66; two studies; 1602 participants; high quality evidence), deep vein thrombosis (DVT) (OR 0.79, 95% CI 0.29 to 2.13; two studies; 1602 participants; high quality evidence) and major bleeding (OR 0.50, 95% CI 0.15 to 1.68; two studies; 1527 participants; high quality evidence).For oral factor Xa inhibitors, when we combined the three included studies together in meta-analyses, there was significant heterogeneity for recurrent pulmonary embolism (OR 1.08, 95% CI 0.46 to 2.56; two studies; 4509 participants; I(2) = 58%; moderate quality evidence). The oral factor Xa inhibitors were no more or less effective in the prevention of recurrent venous thromboembolism (OR 0.85, 95% CI 0.63 to 1.15; three studies; 6295 participants; high quality evidence), DVT (OR 0.72, 95% CI 0.39 to 1.32; two studies; 4509 participants; high quality evidence), all-cause mortality (OR 1.16, 95% CI 0.79 to 1.70; one study; 4817 participants; moderate quality evidence) or major bleeding (OR 0.97, 95% CI 0.59 to 1.62; two studies; 4507 participants; high quality evidence). None of the studies measured quality of life.

AUTHORS' CONCLUSIONS

Moderate to high quality evidence suggests that there are no differences between DOACs and standard anticoagulation for the long-term treatment of pulmonary embolism, for the outcomes recurrent pulmonary embolism, recurrent venous thromboembolism, DVT, all-cause mortality and major bleeding.

Perioperative venous thromboembolic disease and the emerging role of the novel oral anticoagulants: an analysis of the implications for perioperative management

Venous thromboembolism includes 2 inter-related conditions: Deep venous thrombosis and pulmonary embolism. Heparin and low-molecular-weight heparin followed by oral anticoagulation with vitamin K agonists is the first line and current accepted standard therapy with good efficacy. However, this therapeutic strategy has many limitations including the significant risk of bleeding and drug, food and disease interactions that require frequent monitoring. Dabigatran, rivaroxaban, apixaban, and edoxaban are the novel oral anticoagulants that are available for use in stroke prevention in atrial fibrillation and for the treatment and prevention of venous thromboembolism (HYPERLINK\l ”1). Recent prospective randomized trials comparing the NOACs with warfarin have shown similar efficacy between the treatment strategies but fewer bleeding episodes with the NOACs. This paper presents an evidence-based review describing the efficacy and safety of the new anticoagulants compared to warfarin.

Risk of Fatal Bleeding in Episodes of Major Bleeding with New Oral Anticoagulants and Vitamin K Antagonists: A Systematic Review and Meta-Analysis

BACKGROUND

The reversibility of new/novel oral anticoagulants (NOAC) is not well understood, whereas the reversal strategies for bleeding associated with vitamin k antagonists (VKA), such as warfarin, is well established. It is unknown whether outcomes are different between bleeds occurring with NOAC compared to VKA use.

OBJECTIVES

This systematic review and meta-analysis of randomized controlled trials determines the relative odds of fatal bleeding given that a patient suffered a major bleed while on NOAC versus VKA therapy.

SEARCH METHODS

Data on major and fatal bleeding events was sought from randomized controlled trials of NOAC agents compared to VKAs.

MAIN RESULTS

20 trials were included in the meta-analysis. From which, 4056 first-time, major bleeding events were reported and included in the primary analysis. The summary odds ratio for the conditional odds of fatal bleeding given that a major bleeding event occurred was 0.65 [0.52, 0.81] favoring the NOAC agents (p = 0.0001). The reduced odds of fatal bleeding with NOACs was not demonstrated after controlling for bleeding location. Given that an intracranial bleeding event occurred, the summary odds ratio for the conditional odds of fatal bleeding was 0.96 [0.70, 1.32]. For extracranial bleeding events, the summary odds ratio was also statistically insignificant at 0.945 [0.66, 1.35]. AUTHOR’S CONCLUSIONS: The odds ratio calculated in this meta-analysis showed a reduced odds of death in major bleeding associated with NOAC use. This risk reduction was due to a disproportionate amount of intracranial bleeding in the VKA arms. For any given bleeding site, there was no evidence of a significant difference in fatal outcomes from bleeds associated with NOAC versus VKA use.

PROTOCOL REGISTRATION

Protocol registered on PROSPERO under CRD42014013294.

Oral direct thrombin inhibitors or oral factor Xa inhibitors for the treatment of deep vein thrombosis

BACKGROUND

Deep vein thrombosis (DVT) is a condition in which a clot forms in the deep veins, most commonly of the leg. It occurs in approximately 1 in 1,000 people. If left untreated, the clot can travel up to the lungs and cause a potentially life-threatening pulmonary embolism (PE). Previously, a DVT was treated with the anticoagulants heparin and vitamin K antagonists. However, two forms of novel oral anticoagulants (NOACs) have been developed: oral direct thrombin inhibitors (DTI) and oral factor Xa inhibitors. The new drugs have characteristics that may be favourable over conventional treatment, including oral administration, a predictable effect, lack of frequent monitoring or re-dosing and few known drug interactions. To date, no Cochrane review has measured the effectiveness and safety of these drugs in the treatment of DVT.

OBJECTIVES

To assess the effectiveness of oral DTIs and oral factor Xa inhibitors for the treatment of DVT.

SEARCH METHODS

The Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched January 2015) and the Cochrane Register of Studies (last searched January 2015). We searched clinical trials databases for details of ongoing or unpublished studies and the reference lists of relevant articles retrieved by electronic searches for additional citations.

SELECTION CRITERIA

We included randomised controlled trials in which people with a DVT confirmed by standard imaging techniques, were allocated to receive an oral DTI or an oral factor Xa inhibitor for the treatment of DVT.

DATA COLLECTION AND ANALYSIS

Two review authors (LR, JM) independently extracted the data and assessed the risk of bias in the trials. Any disagreements were resolved by discussion with the third review author (PK). We performed meta-analyses when we considered heterogeneity low. The two primary outcomes were recurrent VTE and PE. Other outcomes included all-cause mortality and major bleeding. We calculated all outcomes using an odds ratio (OR) with a 95% confidence interval (CI).

MAIN RESULTS

We included 11 randomised controlled trials of 27,945 participants. Three studies tested oral DTIs (two dabigatran and one ximelagatran), while eight tested oral factor Xa inhibitors (four rivaroxaban, two apixaban and two edoxaban). We deemed all included studies to be of high methodological quality and low risk of bias. The quality of the evidence was graded as high as the outcomes were direct and effect estimates were consistent and precise, as reflected in the narrow CIs around the ORs. Meta-analysis of three studies (7596 participants) comparing oral DTIs with standard anticoagulation groups showed no difference in the rate of recurrent VTE (OR 1.09; 95% CI 0.80 to 1.49), recurrent DVT (OR 1.08; 95% CI 0.74 to 1.58), fatal PE (OR 1.00; 95% CI 0.27 to 3.70), non-fatal PE (OR 1.12; 95% CI 0.66 to 1.90) or all-cause mortality (OR 0.82; 95% CI 0.60 to 1.13). However, oral DTIs were associated with reduced bleeding (OR 0.68; 95% CI 0.47 to 0.98). Meta-analysis of eight studies (16,356 participants) comparing oral factor Xa inhibitors with standard anticoagulation demonstrated a similar rate of recurrent VTE between the two treatments (OR 0.89; 95% CI 0.73 to 1.07). Oral factor Xa inhibitors were associated with a lower rate of recurrent DVT (OR 0.75; 95% CI 0.57 to 0.98). However, this was a weak association, heavily dependent on one study. The rate of fatal (OR 1.20; 95% CI 0.71 to 2.03), non-fatal PE (OR 0.94; 95% CI 0.68 to 1.28) and all-cause mortality (OR 0.90; 95% CI 0.65 to 1.23) was similar between the two treatment groups. Oral factor Xa inhibitors were also associated with reduced bleeding (OR 0.57; 95% CI 0.43 to 0.76). None of the included studies measured post-thrombotic syndrome or health-related quality of life.

AUTHORS' CONCLUSIONS

NOACs such as DTIs and factor Xa inhibitors may be an effective and safe alternative to conventional anticoagulation treatment for acute DVT.

Index clinical manifestation of venous thromboembolism predicts early recurrence type and frequency: a meta-analysis of randomized controlled trials

BACKGROUND

Observational studies suggest index clinical manifestation of venous thromboembolism (VTE) predicts recurrence type. Data regarding the association between index manifestation and recurrence rates are conflicting.

OBJECTIVES

To perform a meta-analysis of randomized controlled trials (RCTs) to determine the type and frequency of recurrent VTE (rVTE) in persons after an index deep vein thrombosis (DVT) or pulmonary embolism (PE).

PATIENTS/METHODS

We searched bibliographic databases for RCTs of acute (early) treatment of rVTE in persons with an index DVT or PE (±DVT), enrolling ≥ 50 subjects anticoagulated ≥ 3-months and reporting types of rVTE. We pooled (random-effects) the proportion of rVTEs that were DVTs, PEs, and fatal PEs, the proportion of recurrent PEs that were fatal, and absolute rVTE rates.

RESULTS

In nine RCTs (N = 13 640; 413 rVTEs) evaluating persons with an index PE; 66% (95% CI, 60-72%) of rVTEs were PE and 27% (95% CI, 22-33%) were fatal PE. Among 25 RCTs (N = 17 340; 692 rVTEs) evaluating persons with an index DVT, 36% (95% CI, 29-44%) experienced a recurrent PE and 10% (95% CI, 7-13%) a fatal PE. Recurrent PEs following an index PE had a higher fatality rate than after an index DVT (41%; 95% CI, 33-48% vs. 25%; 95% CI, 18-33%; P = 0.007). The rVTE rate was higher following an index DVT compared with a PE (2.6%; 95% CI, 1.6-3.8% vs. 4.9%; 95% CI, 4.0-6.0%; P = 0.002).

CONCLUSIONS

Our meta-analysis suggests most rVTEs will be the same type as the index event. While index DVTs are associated with a higher rVTE rate than index PEs; recurrent PEs are associated with high fatality.

Efficacy and Harms of Direct Oral Anticoagulants in the Elderly for Stroke Prevention in Atrial Fibrillation and Secondary Prevention of Venous Thromboembolism: Systematic Review and Meta-Analysis

BACKGROUND

Evidence regarding the use of direct oral anticoagulants (DOACs) in the elderly, particularly bleeding risks, is unclear despite the presence of greater comorbidities, polypharmacy, and altered pharmacokinetics in this age group.

METHODS AND RESULTS

We performed a systematic review and meta-analysis of randomized trials of DOACs (dabigatran, apixaban, rivaroxaban, and edoxaban) for efficacy and bleeding outcomes in comparison with vitamin K antagonists (VKA) in elderly participants (aged ≥75 years) treated for acute venous thromboembolism or stroke prevention in atrial fibrillation. Nineteen studies were eligible for inclusion, but only 11 reported data specifically for elderly participants. The efficacy in managing thrombotic risks for each DOAC was similar or superior to VKA in elderly patients. A nonsignificantly higher risk of major bleeding than with VKA was observed with dabigatran 150 mg (odds ratio, 1.18; 95% confidence interval, 0.97-1.44) but not with the 110-mg dose. Significantly higher gastrointestinal bleeding risks with dabigatran 150 mg (1.78, 1.35-2.35) and dabigatran 110 mg (1.40, 1.04-1.90) and lower intracranial bleeding risks than VKA for dabigatran 150 mg (0.43, 0.26-0.72) and dabigatran 110 mg (0.36, 0.22-0.61) were also observed. A significantly lower major bleeding risk in comparison with VKA was observed for apixaban (0.63, 0.51-0.77), edoxaban 60 mg (0.81, 0.67-0.98), and 30 mg (0.46, 0.38-0.57), whereas rivaroxaban showed similar risks.

CONCLUSIONS

DOACs demonstrated at least equal efficacy to VKA in managing thrombotic risks in the elderly, but bleeding patterns were distinct. In particular, dabigatran was associated with a higher risk of gastrointestinal bleeding than VKA. Insufficient published data for apixaban, edoxaban, and rivaroxaban indicate that further work is needed to clarify the bleeding risks of these DOACs in the elderly.

SYSTEMATIC REVIEW REGISTRATION

http://www.crd.york.ac.uk/PROSPERO. Unique identifier: PROSPERO CRD42014007171/.

Direct oral anticoagulants in patients with VTE and cancer: a systematic review and meta-analysis

BACKGROUND

Direct oral anticoagulants (DOAs) have been shown to be as effective and at least as safe as conventional anticoagulation for the prevention of recurrences in patients with VTE. Whether this is the case in patients with cancer-associated VTE remains undefined.

METHODS

We performed a meta-analysis of randomized controlled trials with the aim of assessing the efficacy and safety of DOAs in patients with VTE and cancer. MEDLINE, EMBASE, and CENTRAL were searched up to December 2013 with no language restriction. The primary outcome of the analysis was recurrent VTE. Data on major bleeding (MB) and clinically relevant nonmajor bleeding were analyzed. Data were pooled and compared by ORs and 95% CIs.

RESULTS

Overall, 10 studies comparing DOAs with conventional anticoagulation for treatment of VTE including patients with cancer were included in the review. Six studies were included in the meta-analysis (two with dabigatran, two with rivaroxaban, one with edoxaban, and one with apixaban), accounting for a total of 1,132 patients. VTE recurred in 23 of 595 (3.9%) and in 32 of 537 (6.0%) patients with cancer treated with DOAs and conventional treatment, respectively (OR, 0.63; 95% CI, 0.37-1.10; I2, 0%). MB occurred in 3.2% and 4.2% of patients receiving DOAs and conventional treatment, respectively (OR, 0.77; 95% CI, 0.41-1.44; I2, 0%).

CONCLUSIONS

DOAs seem to be as effective and safe as conventional treatment for the prevention of VTE in patients with cancer. Further clinical trials in patients with cancer-associated VTE should be performed to confirm these results.

A meta-analysis of randomized controlled trials of the risk of bleeding with apixaban versus vitamin K antagonists

Apixaban is one of the new oral anticoagulants, which is prescribed as an alternative to vitamin K antagonists (VKAs). Concerns regarding its bleeding profile persist and require further evaluation. Therefore, we conducted a meta-analysis of randomized controlled trials (RCTs) to compare the risks of bleeding and all-cause mortality between apixaban and VKAs. The MEDLINE, EMBASE, and Cochrane Library of Clinical Trials databases were systematically searched for RCTs comparing the risks of bleeding and all-cause mortality of apixaban (2.5 or 5 mg twice daily) with those of VKAs. We included RCTs conducted in adults and published in English or French. Data were pooled across RCTs using random-effects meta-analytical models. Our systematic search identified 5 RCTs meeting our inclusion criteria (n = 24,435). They included patients with atrial fibrillation (n = 18,358), total knee replacement surgery (n = 458), and venous thromboembolism (n = 5,619). Data pooled across RCTs revealed that apixaban was associated with reduced risks of any bleeding (relative risk [RR] 0.73, 95% confidence interval [CI] 0.59 to 0.90) and a composite of major or clinically relevant nonmajor bleeding (RR 0.60, 95% CI 0.40 to 0.88). Apixaban was also associated with a lower risk of intracranial bleeding (RR 0.42, 95% CI 0.31 to 0.58) whereas analyses of major and minor bleeding were inconclusive. Moreover, apixaban was associated with decreased all-cause mortality (RR 0.89, 95% CI 0.81 to 0.99) although this finding was driven by the results of the ARISTOTLE trial. In conclusion, our meta-analysis found that apixaban is associated with a lower risk of bleeding than VKAs, providing some reassurance regarding its safety.

[Proper use of apixaban: an outline for clinical practice]

Apixaban is a direct inhibitor of coagulation factor Xa. Superior efficacy over aspirin and antivitamin K has been shown in the prevention of stroke and systemic embolism during non-valvular atrial fibrillation with a more favorable safety profile, even though the risk of hemorrhage cannot be ignored, considering its mechanism of action. The recommended dose is 5mg twice daily which can be reduced to 2.5mg depending on the individual risk. Apixaban is also indicated for the treatment of venous thromboembolism but reimbursement has not yet been accepted in France for this indication. As with all direct oral anticoagulants, no routine biological monitoring is required, nevertheless their use may have an impact on all coagulation tests, eventually hampering interpretation. In particular clinical circumstances where a measure of anticoagulant efficacy is deemed necessary, specific assay of anti-Xa activity is appropriate, the result being expressed as concentration of the anticoagulant used. It is therefore necessary to state the name of the medicine for which the assay is requested. With these new anticoagulants, management of hemorrhagic events can be more difficult due to the lack of a specific antidote. Pro-hemostatic substances have exhibited efficacy in animal models but results are still insufficiently documented in clinical practice. Local or locoregional hemostasis measurements, when possible, are an essential factor in the treatment of hemorrhagic events.

Development of apixaban: a novel anticoagulant for prevention of stroke in patients with atrial fibrillation

The factor Xa inhibitor apixaban is one of the novel anticoagulants to emerge as alternatives to long-standing standards of care that include low-molecular-weight heparin and warfarin. The development of apixaban reflects a strategy to optimize the clinical pharmacology profile, dosing posology, trial designs, and statistical analyses across multiple indications, and to seek alignment with global health authorities. The primary objective of dose selection was to maintain balance between efficacy and bleeding risk. Twice-daily dosing of apixaban, rather than once daily, was chosen to lower peak concentrations and reduce fluctuations between peak and trough levels. Our discussion here focuses on the use of apixaban for stroke prevention in nonvalvular atrial fibrillation (NVAF). Supporting this indication, a pair of registrational trials was conducted that enrolled the full spectrum of patients who, by guidelines, were eligible for anticoagulation. In the AVERROES study of patients who were unsuitable for warfarin therapy, apixaban was superior to aspirin in reducing the risk of stroke or systemic embolism (SSE), without a significant increase in major bleeding (MB). In the ARISTOTLE (Apixaban for Reduction In STroke and Other ThromboemboLic Events in Atrial Fibrillation) study, apixaban was superior to warfarin on the rates of SSE, MB, and all-cause mortality. Overall, these studies have demonstrated a substantially favorable benefit–risk profile for apixaban over warfarin and aspirin in NVAF.