Dabigatran and postmarketing reports of bleeding

Clinical Studies with Anticoagulants that Have Changed Clinical Practice

Anticoagulant therapy is the cornerstone of treatment and prevention of arterial and venous thromboembolism. Taking a historical perspective, starting in the 1960s, and progressing through to 2022, we discuss key clinical trials of anticoagulants that have changed clinical practice, and examine obstacles encountered in bringing these anticoagulants to the clinic. The design of some of the early studies that shaped clinical practice was poor by current standards, but their results were influential because nothing better was available. Both heparin and vitamin K antagonists had been in clinical use for several decades before well-designed trials in the 1980s optimized their dosing and enhanced their safety and efficacy. Low-molecular-weight heparin then replaced unfractionated heparin because it had a more predictable dose-response and a longer half-life, thereby allowing it to be used conveniently in out-of-hospital settings. More recently, direct oral anticoagulants became the oral anticoagulants of choice for most indications because they were shown to be at least as safe and effective as vitamin K antagonists when used in fixed doses without the need for laboratory monitoring. The design of the trials that led to the approval of the direct oral anticoagulants was excellent, but further studies are required to optimize their dosing in selected patients who were underrepresented in these trials.

Effect of ABCB1 Gene Carriage and Drug-Drug Interactions on Apixaban and Rivaroxaban Pharmacokinetics and Clinical Outcomes in Patients with Atrial Fibrillation and Deep Vein Thrombosis

Aim. To investigate the effect of ABCB1 gene carriage and interdrug interactions on apixaban pharmacokinetics and clinical outcomes in patients with atrial fibrillation and deep vein thrombosis.

Material and methods. Patients hospitalized at Yudin State Clinical Hospital participated in the study. A total of 92 patients (50 patients received apixaban and 42 – rivaroxaban) with non-valvular atrial fibrillation and deep vein thrombosis were included. Genotyping was performed by real-time polymerase chain reaction. Direct oral anticoagulants concentrations were measured using an electrospray ionization mass spectrometer in positive ionization mode.

Results. In our study we found that in patients carrying the CT+TT ABCB1 (rs4148738) C>T genotype encoding the carrier protein (P-gp), the plasma concentration of rivaroxaban was statistically significantly higher p= 0.026. In addition, we found that patients taking apixaban together with a CYP3A4/P-gp inhibitor were 3.5 times more likely to have hemorrhagic complications than those without inhibitors p = 0.004.

Conclusion. Our study revealed that the plasma concentration of rivaroxaban was higher in patients carrying the ABCB1 (rs4148738) C>T polymorphism T allele. And patients taking apixaban together with CYP3A4/P-gp inhibitor had higher risk of hemorrhagic complications in comparison with patients not taking such drugs. Further studies are needed on the influence of pharmacogenetics and pharmacokinetics on the safety and efficacy profile of apixaban and rivaroxaban, taking into account the trend of systemic approach to optimization of anticoagulant therapy of direct oral anticoagulants based on pharmacokinetic, pharmacogenetic biomarkers.

Analysis of Adverse Events in the Treatment of Patients with Non-Valvular Atrial Fibrillation with Oral Anticoagulants: Data from the "ANTEY" Observational Study

Rationale. Therapy with oral anticoagulants (OACs) in patients with atrial fibrillation (AF) is based on finding the optimal balance of efficacy and safety of these drugs. Data from observational studies are an additional source of information for the adverse events (AEs) of pharmacotherapy. Objective: To investigate pharmacotherapy AEs with OACs in the “ANTEY” prospective observational study in patients with non-valvular atrial fibrillation (AF). Material and Methods: A total of 201 people were enrolled (83 (41.3%) were women). The age of subjects was 71.1 ± 8.7 years (data presented as mean with standard deviation). The study protocol included two face-to-face visits (contacts V0 and V1) and one follow-up (FU) phone contact which were made with the patient at an interval of 6 months. At V0, all patients were recommended to take one of the non-vitamin K antagonist oral anticoagulants (NOACs); starting from V1, warfarin could have been prescribed or NOAC could have been changed. Information about AEs and OACsadministration was collected at V0, V1, and FU. Results. During 1 year of observation, 15 out of 201 patients refused to take OACs, and 186 initiated the recommended drug. Rivaroxaban was initiated in 93 patients, dabigatran in 46, apixaban in 40, and warfarin in 7 patients. There were 55 AEs, 25 of which were serious (SAEs), including 4 deaths. Of the 30 AEs, there were 18 bleedings: eight (8.6%) occurred with the administration of rivaroxaban; four (8.5%) with dabigatran, three (7.5%) with apixaban, and three (42.9%) with warfarin. Differences in the incidence of bleeding events between NOACs and warfarin are statistically significant (p = 0.025). Any AEs increased the chance of nonadherence to treatment nine-fold: OR = 9.2 (CI95%: 3.6−23.5), p < 0.0001. Conclusions. The most typical and common AEs in real-world clinical practice settings treatment with OACs were bleedings, the incidence of which was approximately 8% to 9% in the treatment with NOACs and was much higher with warfarin, bleedings in the treatment with OACs are statistically significantly associated with nonadherence to the use of these drugs in the future.

Gastrointestinal Bleeding: a Cardiologist's Point of View

Oral anticoagulant therapy is widely used in different patients for the prevention and treatment of thromboembolic events: in atrial fibrillation, deep vein thrombosis/pulmonary embolism, acute coronary syndrome, in the early postoperative period after orthopedic surgery. Nowadays it is possible to use vitamin K antagonists (warfarin) as well as direct oral anticoagulants (DOAC): dabigatran, rivaroxaban, apixaban and edoxaban. The mai complication of any anticoagulant therapy is bleeding (gastrointestinal, intracranial, etc.), which seriously limits its usage. In this review the incidence of gastrointestinal bleeding (GIB) associated with oral anticoagulants intake was analyzed according to the results of both large randomized and postregistration trials. Furthermore, the effect of age on the risk of GIB development is discussed, and also aspects of the pathophysiology of gastrointestinal mucosa lesions in patients taking DOAC are considered.

Serial use of existing clinical decisions aids can reduce computed tomography pulmonary angiography for pulmonary embolism

Pulmonary embolism (PE) remains a diagnostic challenge in emergency medicine. Clinical decision aids (CDAs) like the Pulmonary Embolism Rule-Out Criteria (PERC) are sensitive but poorly specific; serial CDA use may improve specificity. The goal of this before-and-after study was to determine if serial use of existing CDAs in a novel diagnostic algorithm safely decreases the use of CT pulmonary angiograms (CTPA). This was a retrospective before-and-after study conducted at an urban ED with 105,000 annual visits. Our algorithm uses PERC, Wells' score, and D-dimer in series, before moving to CTPA. The algorithm was introduced in January, 2017. Use of CDAs and D-dimer in the 24 months pre- and 12 months post-intervention were obtained by chart review. The algorithm's effect on CTPA ordering was assessed by comparing volume 5 years pre- and 3 years post-intervention, adjusted for ED volume. Mean CTPAs per 1000 adult ED visits was 11.1 in the 5 pre-intervention years and 9.9 in the 3 post-intervention years (p < 0.0001). Use of PERC, Wells' score and D-dimer increased from 1.1%, 1.1%, and 28% to 8.8% (p = 0.0002) 8.1% (p = 0.0005), and 35% (p = 0.0066), respectively. Pre-intervention, there were six potentially missed PEs compared to three in the post-intervention period. Introduction of our serial CDA diagnostic algorithm was associated with increased use of CDAs and D-dimer and reduced CTPA rate without an apparent increase in the number of missed PEs. Prospective validation is needed to confirm these results.

Conducting Real-world Evidence Studies on the Clinical Outcomes of Diabetes Treatments

Real-world evidence (RWE), the understanding of treatment effectiveness in clinical practice generated from longitudinal patient-level data from the routine operation of the healthcare system, is thought to complement evidence on the efficacy of medications from randomized controlled trials (RCTs). RWE studies follow a structured approach. (1) A design layer decides on the study design, which is driven by the study question and refined by a medically informed target population, patient-informed outcomes, and biologically informed effect windows. Imagining the randomized trial we would ideally perform before designing an RWE study in its likeness reduces bias; the new-user active comparator cohort design has proven useful in many RWE studies of diabetes treatments. (2) A measurement layer transforms the longitudinal patient-level data stream into variables that identify the study population, the pre-exposure patient characteristics, the treatment, and the treatment-emergent outcomes. Working with secondary data increases the measurement complexity compared to primary data collection that we find in most RCTs. (3) An analysis layer focuses on the causal treatment effect estimation. Propensity score analyses have gained in popularity to minimize confounding in healthcare database analyses. Well-understood investigator errors, like immortal time bias, adjustment for causal intermediates, or reverse causation, should be avoided. To increase reproducibility of RWE findings, studies require full implementation transparency. This article integrates state-of-the-art knowledge on how to conduct and review RWE studies on diabetes treatments to maximize study validity and ultimately increased confidence in RWE-based decision making.

An emulated target trial analysis based on Medicare data suggested non-inferiority of Dabigatran versus Rivaroxaban

OBJECTIVES

Rivaroxaban and Dabigatran were the first two non-vitamin K antagonist oral anticoagulants (NOACs) for preventing stroke among non-valvular Atrial Fibrillation patients. This article aimed to evaluate the relative efficacy and safety of Rivaroxaban versus Dabigatran.

STUDY DESIGN AND SETTING

An emulated target trial analysis was conducted based on Medicare, in which we constructed three "randomized clinical trials" with well-defined inclusion/exclusion criteria, treatment regimens, and analysis procedures. We analyzed the individual trials, examined temporal variations, and generated unified results via pooled analysis.

RESULTS

With a two-year data collection window (2012-2013), 70,129 subjects were enrolled in the three emulated trials, with 36,269 and 34,089 in the Rivaroxaban and Dabigatran arms, respectively. Dabigatran (the reference group for hazard ratio - HR) was superior regarding time to any primary event (including ischemic stroke, other thromboembolic events, major bleeding, and death; HR 1.232, P-value 0.0025), major bleeding (HR 1.187, P-value <0.0001), and mortality (HR 1.488, P-value <0.0001). Differences regarding stroke and other thromboembolic events were not significant.

CONCLUSION

Dabigatran was found as superior for the Medicare patients with multiple chronic conditions. Temporal variations, which had been largely neglected in the literature, were observed. This study may provide new insight into treating AF with NOACs.

Gastrointestinal Bleeding and Direct Oral Anticoagulants among Patients with Atrial Fibrillation: Risk, Prevention, Management, and Quality of Life

A significant problem for patients undergoing oral anticoagulation therapy is gastrointestinal bleeding (GIB), a problem that has become increasingly urgent following the introduction of direct oral anticoagulants (DOACs). Furthermore, in recent years a greater focus has been placed on the quality of life (QOL) of patients on long-term oral anticoagulant therapy, which necessitates changes in lifestyle, as well as posing an increased risk of bleeding without producing objective symptomatic relief. Here, we examine current evidence linked to GIB associated with oral anticoagulants, with a focus on randomized control trials, meta-analyses, and postmarketing observational studies. Rivaroxaban and dabigatran (especially the 150-mg bis-in-die dose) appeared to be linked to an increased risk of GIB. The risk of GIB was also greater when edoxaban was used, although this was dependent on the dose. Apixaban did not pose a higher risk of GIB in comparison with warfarin. We provided a summary of current knowledge regarding GIB risk factors for individual anticoagulants, prevention strategies that lower the risk of GIB and management of DOAC therapy after a GIB episode.

Adverse drug reactions with oral anticoagulants: data from sicilian spontaneous reporting system database

OBJECTIVE

Direct oral anticoagulants (DOACs) were developed to avoid the limitations of vitamin K antagonists (VKAs). DOACs are associated with a greater incidence of gastrointestinal bleeding and a smaller number of intracranial haemorrhages than VKAs. Therefore, it is important to deepen our knowledge of their safety profiles. The aim of this study was thus to analyse adverse drug reaction (ADR) reports on DOACs and VKAs using the Sicilian Spontaneous Reporting System (SRS) database.

METHODS

All ADR reports with DOACs and VKAs as suspected drugs that were entered into the Sicilian SRS database during the period 2001-2019 were selected. In detail, all reports with the following single active substances were included: dabigatran etexilate, rivaroxaban, apixaban and edoxaban; acenocoumarol and warfarin were included as a comparator group. Descriptive statistical methodology was used to evaluate characteristics of the reported cases with a case-by-case assessment.

RESULTS AND DISCUSSION

Out of 521 reports related to anticoagulants, 444 (85.2%) and 77 (14.8%) involved DOACs and VKAs, respectively. DOAC-related reports were mainly of gastrointestinal disorders. In contrast, VKAs were mostly associated with blood and lymphatic system disorders, injury, investigations and vascular disorders. Many more cases of ADRs in the form of gastrointestinal disorders concerned dabigatran etexilate (n = 179, 73.7%) than the other DOACs, while ADRs in the form of blood disorders were mainly associated with acenocoumarol (n = 27, 57.4%). The most commonly reported Preferred Terms for DOACs were dyspepsia (n = 89, 17.1%), upper abdominal pain (n = 41, 9.2%) and pruritus (n = 26, 5.8%), whereas for VKAs, they were anaemia (n = 21, 27.3%) and hypocoagulable state (n = 18, 3.5%). Potentially interacting concomitant medications particularly included antithrombotic agents (n = 19, 4.3%) for DOACs and proton-pump inhibitors (PPIs) (n = 37, 48.1%) and antithrombotic agents (n = 13, 16.9%) for VKAs.

CONCLUSION

The ADRs most commonly associated with DOACs, especially dabigatran, were gastrointestinal disorders, particularly gastrointestinal bleeding. Our study also highlights the potential role of drug-drug interactions in the ADRs. The cases of gastrointestinal bleeding highlight the need for careful prescribing of DOACs and use of potentially interacting concomitant drugs.

The Risk of Gastrointestinal Bleeding between Non-Vitamin K Antagonist Oral Anticoagulants and Vitamin K Antagonists in the Asian Atrial Fibrillation Patients: A Meta-Analysis

Background: Non-vitamin K antagonist oral anticoagulants (NOACs) are more commonly used to prevent atrial fibrillation (AF) patients from thromboembolic events than vitamin K antagonists (VKAs). However, the gastrointestinal bleeding (GIB) risk in the Asian AF patients associated with NOACs in comparison with VKAs remained unaddressed. Materials and Methods: A systematic search of studies on NOACs and VKAs in the Asian AF patients was conducted in PubMed, Cochrane Library, and ClinicalTrials.gov. The primary outcome was the hazard ratio (HR) of any GIB associated with NOACs versus VKAs. The secondary outcome was the GIB risks in different kinds of NOACs compared with VKAs. Results: This meta-analysis included two randomized controlled trials (RCTs) and four retrospective studies, comprising at least 200,000 patients in total. A significantly lower HR of GIB risks was found in all kinds of NOACs than VKAs in the Asian AF patients (HR: 0.633; 95% confidence interval: 0.535-0.748; p < 0.001). Additionally, the GIB risks of different NOACs were apixaban (HR: 0.392), edoxaban (HR: 0.603), dabigatran (HR: 0.685), and rivaroxaban (HR: 0.794), respectively. Conclusions: NOACs significantly reduced the risk of GIB in the Asian AF patients compared with VKAs. In the four NOACs compared with VKAs, apixaban probably had a trend of the least GIB risk. We need further head-to-head studies of different NOACs to confirm which NOAC is the most suitable for Asian AF patients and to know the optimal dosage regimen of different NOACs.

Assessing Safety of Direct Thrombin Inhibitors, Direct Factor Xa Inhibitors and Vitamin K Antagonists in Patients with Atrial Fibrillation: A Nation-Wide Propensity Score Matched Cohort from Sweden

Purpose

To evaluate associations between first-time use of direct oral anticoagulants or vitamin K antagonists and bleeding risk or mortality in the elderly with atrial fibrillation in a real-world setting in Sweden.

Patients and Methods

The study population comprises first-time users, above age 60, of dabigatran, apixaban, rivaroxaban, or warfarin, with first atrial fibrillation occurrence within 6 months before dispensing (2012–2016). Outcomes were gastrointestinal, any, or intracranial bleeding, and mortality. Exposure started at first dispensing of a study drug. Follow-up continued until outcome, end of drug supply, dispensing of another study drug, death or end of study (December 2016). We conducted a propensity score matched, nationwide register-based cohort study including three treatment groups: direct thrombin inhibitors, direct factor Xa inhibitors and vitamin K antagonists, each compared to the other two, focusing on subgroups of age and sex. Cox proportional hazard models adjusted for CHA2DS2VASc and HAS-BLED scores provided hazard ratios with 95% confidence intervals.

Results

The matched study populations consisted of 7,264 patients for the direct thrombin inhibitors vs vitamin K antagonists comparison, 12,566 patients for the direct factor Xa inhibitors vs vitamin K antagonists comparison and 6,606 patients for the direct factor Xa inhibitors vs direct thrombin inhibitors comparison, in total 26,436 patients. Numerically high, but imprecise, hazard ratios for gastrointestinal bleeding were observed for women aged 75–80, 80–85, or above 85 years, eg 6.00 (1.02, 113.47) for direct thrombin inhibitors vs vitamin K antagonists. For both sexes, numerically high hazard ratios for any bleeding were observed in ages 80–85, or above 85 years, eg 2.90 (1.01, 10.41) for direct thrombin inhibitors vs vitamin K antagonists. Numerically high HRs for intracranial bleeding were observed for women aged 75–80 or 80–85 years, eg 2.70 (0.65, 18.19) for direct factor Xa inhibitors vs vitamin K antagonists. Excess mortality was observed in both sexes, across age groups, for naive and experienced anticoagulant users.

Conclusion

The observed increased gastrointestinal bleeding risk in first-time users of direct thrombin inhibitors or direct factor Xa inhibitors is consistent with previous studies. The possible risk of excess mortality merits further studies.

Non-vitamin K antagonist oral anticoagulants and sport

Physical activity is worldwide recommended for its benefits on cardiovascular system. There is an increasing number of people of all ages that approach sport activity both as leisure time physical activity and as competitive sport. It is always more frequent the request even from older subjects and cardiac patients to be allowed to practice physical activity. Some problems could arise when these subjects present or develop pathologic conditions that require specific pharmacological treatment, in particular an anticoagulation therapy. This review focalizes on the management of oral anticoagulant therapy (OAT) in patients practicing sport activity, especially due to atrial fibrillation and deep vein thrombosis, which represent two highly prevalent conditions, particularly with increasing age. Official recommendations in this field may appear limiting for patients, forbidding in the majority of cases sports at risk of trauma and consequent bleeding. These recommendations still resent the heritage of the "traditional" management of OAT, mainly represented by vitamin-K antagonists (VKAs). The non-vitamin K antagonist oral anticoagulants, with their more favorable pharmacokinetic-pharmacodynamic profile compare to VKAs, may now represent an opportunity to modify the approach to sport activity in patients with an indication to OAT. This review of the literature deals with possible strategies to overcome the present limitations for OAT subjects willing to pursue a healthy lifestyle, that include sport activity, minimizing at the same time their risk of bleeding.

CYP2C19*17 May Increase the Risk of Death Among Patients with an Acute Coronary Syndrome and Non-Valvular Atrial Fibrillation Who Receive Clopidogrel and Rivaroxaban

INTRODUCTION

The aim of this study is to assess the influence of gene CYP2C19, CYP3A4, CYP3A5 and ABCB1 polymorphisms on clopidogrel antiplatelet activity, rivaroxaban concentration equilibrium, and clinical outcomes among patients with acute coronary syndrome and non-valvular atrial fibrillation.

METHODS

In the multicenter prospective registry study of the efficacy and safety of a combined antithrombotic therapy 103 patients with non-valvular atrial fibrillation both undergoing or not a percutaneous coronary intervention were enrolled. The trial assessed the primary outcomes (major bleeding, in-hospital death, cardiovascular death, stroke\transient ischaemic attack, death/renal insufficiency) and secondary outcomes (platelet reactivity units (PRU), rivaroxaban concentration).

RESULTS

For none of the clinical outcomes when combined with other covariates, the carriership of polymorphisms CYP3A5*3 rs776746, CYP2C19*2 rs4244285;*17 rs12248560, ABCB1 3435 C>T, ABCB1 rs4148738 was significant. None of the markers under study (CYP3A5*3 rs776746, CYP2C19*2 rs4244285, *17 rs12248560, ABCB1 3435 C>T, ABCB1 rs4148738) has proven to affect rivaroxaban equilibrium concentration in blood plasma among patients with atrial fibrillation and acute coronary syndrome.

CONCLUSION

In situations of double or triple antithrombotic rivaroxaban and clopidogrel therapy among patients with atrial fibrillation and acute coronary syndrome, the genetic factors associated with bleeding complications risk (CYP2C19*17) may prove to be clinically relevant.

Antithrombotic Drugs-Pharmacology and Perspectives

Thrombosis, the localized clotting of blood that affects arterial or venous circulation, is one of the leading causes of death worldwide. Arterial thrombosis is commonly initiated by vascular endothelial injury, while venous thrombosis mainly stems from blood stasis. Despite these differences, platelet adhesion, activation and aggregation, and fibrin formation as a result of coagulation constitute the fundamental processes of thrombus formation. Antithrombotic drugs permitted on the clinical currently can dramatically reduce major adverse cardiovascular events; however, they can also increase the bleeding risk. Discovery of antithrombotic drugs that can effectively prevent thrombosis while sparing bleeding side effects remains unmet medical need. In this chapter, we provide an overview on the pathophysiology of thrombosis, followed by introduction of each class of antithrombotic drugs including their pharmacology, clinical applications and limitations. Practical challenges and future perspectives of antithrombotic drugs are discussed in the last part of this chapter.

Direct-Acting Oral Anticoagulants and Their Reversal Agents-An Update

Background: Over the last ten years, a new class of drugs, known as the direct-acting oral anticoagulants (DOACs), have emerged at the forefront of anticoagulation therapy. Like the older generation anticoagulants, DOACs require specific reversal agents in cases of life-threatening bleeding or the need for high-risk surgery. Methods: Published literature was searched, and information extracted to provide an update on DOACS and their reversal agents. Results: The DOACs include the direct thrombin inhibitor—dabigatran, and the factor Xa inhibitors—rivaroxaban, apixaban, edoxaban, and betrixaban. These DOACs all have a rapid onset of action and each has a predictable therapeutic response requiring no monitoring, unlike the older anticoagulants, such as warfarin. Two reversal agents have been approved within the last five years: idarucizumab for the reversal of dabigatran, and andexanet alfa for the reversal of rivaroxaban and apixaban. Additionally, ciraparantag, a potential “universal” reversal agent, is currently under clinical development. Conclusions: A new generation of anticoagulants, the DOACs, and their reversal agents, are gaining prominence in clinical practice, having demonstrated superior efficacy and safety profiles. They are poised to replace traditional anticoagulants including warfarin.

Choosing Among Common Data Models for Real-World Data Analyses Fit for Making Decisions About the Effectiveness of Medical Products

Many real-world data analyses use common data models (CDMs) to standardize terminologies for medication use, medical events and procedures, data structures, and interpretations of data to facilitate analyses across data sources. For decision makers, key aspects that influence the choice of a CDM may include (i) adaptability to a specific question; (ii) transparency to reproduce findings, assess validity, and instill confidence in findings; and (iii) ease and speed of use. Organizing CDMs preserve the original information from a data source and have maximum adaptability. Full mapping data models, or preconfigured rules systems, are easy to use, since all raw codes are mapped to medical constructs. Adaptive rule systems grow libraries of reusable measures that can easily adjust to preserve adaptability, expedite analyses, and ensure study-specific transparency.

Renal Excretion of Dabigatran: The Potential Role of Multidrug and Toxin Extrusion (MATE) Proteins

Following oral administration, dabigatran etexilate (DABE) is rapidly hydrolyzed to its active form, dabigatran. DABE, but not dabigatran, presents as a P-glycoprotein (P-gp) substrate and has increasingly been used as a probe drug. Therefore, although dosed as DABE, a P-gp drug-drug interaction (DDI) is reported as a dabigatran plasma concentration ratio (perpetrator versus placebo). Because the majority of a DABE dose (80 to 85%) is recovered in urine as unchanged dabigatran (renal active secretion is ∼25% of total clearance), dabigatran was evaluated in vitro as a substrate of various human renal transporters. Active (pyrimethamine-sensitive) dabigatran uptake was observed with human embryonic kidney (HEK) 293 cells expressing multidrug and toxin extrusion protein 1 (MATE1) and 2K (MATE2K), with Michaelis-Menten constant (K_m) values of 4.0 and 8.0 μM, respectively. By comparison, no uptake of 2 μM dabigatran (versus mock-transfected HEK293 cells) was evident with HEK293 cells transfected with organic cation transporters (OCT1 and OCT2) and organic anion transporters (OAT1, 2, 3, and 4). The efflux ratios of dabigatran across P-gp- and BCRP (breast cancer resistance protein)-MDCK (Madin-Darby canine kidney) cell monolayers were 1.5 and 2.0 (versus mock-MDCK cell monolayers), suggesting dabigatran is a relatively poor P-gp and BCRP substrate. Three of five drugs (verapamil, ketoconazole, and quinidine) known to interact clinically with dabigatran, as P-gp inhibitors, presented as MATE inhibitors in vitro (IC₅₀ = 1.0 to 25.2 μM). Taken together, although no basolateral transporter was identified for dabigatran, the results suggest that apical MATE1 and MATE2K could play an important role in its renal clearance. MATE-mediated renal secretion of dabigatran needs to be considered when interpreting the results of P-gp DDI studies following DABE administration.

Evaluating utilization patterns of oral anticoagulants in routine care

Essentials Unlike warfarin, treatment with DOACs do not require regular plasma level monitoring. We compared persistence of patients treated with DOACs compared to warfarin. Persistence at 12 months was higher for all DOACs compared to warfarin. Persistence to anticoagulant therapy was generally poor in commercially insured patients.

BACKGROUND

Direct oral anticoagulants (DOACs) were developed as an alternative to vitamin K antagonists for a variety of indications. Unlike warfarin, DOACs do not require regular plasma level monitoring.

OBJECTIVE

We investigated whether this simplification in management affects persistence on DOACs vs warfarin.

METHODS

Within two US commercial health insurance databases (MarketScan and Clinformatics™ DataMart), we compared baseline characteristics and evaluated rates of nonpersistence (≥30-day treatment gap or switching) among patients with nonvalvular atrial fibrillation who initiated an oral anticoagulant between October 2010 and September 2015.

RESULTS

In the larger of the two data sources (MarketScan), we identified 166 690 anticoagulant initiators during the study period. After propensity score (PS) matching, 24 141 dabigatran initiators, 26 066 rivaroxaban, and 12 578 apixaban initiators were included along with the 1:1 matched warfarin initiators. The proportion of patients who were nonpersistent after 12 months was lower for DOAC users (dabigatran 66%, rivaroxaban 60%, apixaban 53%) compared with warfarin users (72%). The same relative ranking was observed in direct comparisons among the DOACs after PS-matching. Findings in Clinformatics DataMart were similar.

CONCLUSION

Results from this long-term surveillance program showed that patients who initiated DOACs were more likely to be persistent to therapy compared with those who initiated warfarin. Persistence to anticoagulant therapy was generally poor in commercially insured patients.

Re-evaluating Safety and Effectiveness of Dabigatran Versus Warfarin in a Nationwide Data Environment: A Prevalent New-User Design Study

Introduction

The new user cohort design is widely used to assess the effects of a new drug, such as dabigatran, but inherently excludes some users due to prior use of the comparator drug, for example warfarin. The prevalent new-user design offers a solution that includes all eligible users of the new drug.

Objective

To evaluate the safety and effectiveness of dabigatran versus warfarin in non-valvular atrial fibrillation (NVAF) patients with prevalent new-user design.

Methods

Taiwan National Health Insurance and mortality data from 2011 through 2015 were utilized. From an incident NVAF cohort, we identified dabigatran initiators as either incident or prevalent (switchers from warfarin) new users. Time- and prescription-based exposure sets were formed for dabigatran initiators to account for prior warfarin prescriptions. A comparable warfarin user was matched on the time-conditional propensity score to the dabigatran initiator in each set. The matched patients were followed for clinical outcomes, with Cox proportional hazards model used to estimate hazard ratios (HRs).

Results

There were 10,811 dabigatran initiators, including 22% prevalent new users (switchers), who formed the exposure sets and were matched 1:1 to warfarin users. Dabigatran use was associated with lower risks of intracranial hemorrhage (HR 0.51; 95% confidence interval [CI] 0.39, 0.66) and gastrointestinal bleeding (HR 0.81; 95% CI 0.70, 0.92), compared with warfarin use. These effects were similar between the incident and prevalent new users.

Conclusion

Using a design that includes both incident and prevalent new users of dabigatran, the use of dabigatran is associated with lower major bleeding risk than warfarin use among patients with incident NVAF.

Electronic supplementary material

The online version of this article (10.1007/s40801-019-0156-2) contains supplementary material, which is available to authorized users.

Data Rich, Information Poor: Can We Use Electronic Health Records to Create a Learning Healthcare System for Pharmaceuticals?

Judicious use of real-world data (RWD) is expected to make all steps in the development and use of pharmaceuticals more effective and efficient, including research and development, regulatory decision making, health technology assessment, pricing, and reimbursement decisions and treatment. A "learning healthcare system" based on electronic health records and other routinely collected data will be required to harness the full potential of RWD to complement evidence based on randomized controlled trials. We describe and illustrate with examples the growing demand for a learning healthcare system; we contrast the exigencies of an efficient pharmaceutical ecosystem in the future with current deficiencies highlighted in recently published Organisation for Economic Co-operation and Development (OECD) reports; and we reflect on the steps necessary to enable the transition from healthcare data to actionable information. A coordinated effort from all stakeholders and international cooperation will be required to increase the speed of implementation of the learning healthcare system, to everybody's benefit.

Evaluating the Use of Nonrandomized Real-World Data Analyses for Regulatory Decision Making

The analysis of longitudinal healthcare data outside of highly controlled parallel-group randomized trials, termed real-world evidence (RWE), has received increasing attention in the medical literature. In this paper, we discuss the potential role of RWE in drug regulation with a focus on the analysis of healthcare databases. We present several cases in which RWE is already used and cases in which RWE could potentially support regulatory decision making. We summarize key issues that investigators and regulators should consider when designing or evaluating such studies, and we propose a structured process for implementing analyses that facilitates regulatory review. We evaluate the empirical evidence base supporting the validity, transparency, and reproducibility of RWE from analysis of healthcare databases and discuss the work that still needs to be done to ensure that such analyses can provide decision-ready evidence on the effectiveness and safety of treatments.

Adverse reaction profiles of hemorrhagic adverse reactions caused by direct oral anticoagulants analyzed using the Food and Drug Administration Adverse Event Reporting System (FAERS) database and the Japanese Adverse Drug Event Report (JADER) database

Direct oral anticoagulants (DOACs) are used in anticoagulant therapy. The purpose of this study was to evaluate the association of DOAC-induced gastrointestinal (GI) and nervous system hemorrhage using the FDA's Adverse Event Reporting System (FAERS) database and the Japanese Adverse Drug Event Report (JADER) database. We identified and analyzed the reports of hemorrhagic reactions between 2004 and 2016 from the FAERS and JADER databases, and calculated the adjusted reported odds ratio (ROR) using the multiple logistic regression method. Additionally, we used the time-to-onset analysis. In the FAERS database, the adjusted ROR of apixaban, rivaroxaban, and dabigatran for GI hemorrhage was 6.79 (5.84-7.91), 19.58 (18.85-20.34), and 14.51 (13.58-15.51), respectively. In the JADER database, the adjusted ROR of apixaban, rivaroxaban, edoxaban, and dabigatran for GI hemorrhage was 11.80 (9.50-14.64), 11.03 (9.18-13.26), 10.17 (6.95-14.88), and 9.85 (7.23-13.42), respectively. We found that the association of GI hemorrhage with DOACs was affected by sex (female). Additionally, 30% of GI hemorrhage was observed after 30 days. Hemorrhagic reactions of both GI and nervous systems were observed in both the spontaneous reporting system databases. We recommend that female patients who experience symptoms related to GI hemorrhage should be closely monitored and advised to adhere to an appropriate care plan. Additionally, our results show that patients should be closely monitored for hemorrhage even after a month.

Pharmacokinetics of new oral anticoagulants: implications for use in routine care

INTRODUCTION

Since 2008, new oral anticoagulants (NOACs) have been approved for the prevention of venous thromboembolism (VTE) in patients receiving hip or knee replacement surgery, prevention of stroke and systemic embolism in patients with non-valvular atrial fibrillation (NVAF), treatment of deep vein thrombosis (DVT), and pulmonary embolism (PE). Premarketing randomized clinical trials (RCTs) of NOACs demonstrated their non-inferiority in terms of efficacy vs. warfarin (traditional oral anticoagulant - TOA), with lower risk of serious adverse drug reactions, especially cerebral hemorrhages. In clinical practice, pharmacokinetic aspects of NOACs have to be carefully taken into account to optimize the benefit-risk profile of these drugs. Areas covered: An overview of major issues related to pharmacokinetics of NOACs, such as drug-drug interactions, over- and underdosage in special populations (e.g. elderly, underweight, and chronic kidney disease patients), and impact on adherence and persistence to NOACs therapy and ultimately clinical outcomes in real-world setting, is provided. Expert opinion: NOACs have been proven to be a better option than traditional anticoagulants due to better tolerability and ease of use. However, given specific pharmacokinetic characteristics, NOAC therapy has to be carefully tailored and monitored in relation to patient characteristics with the final goal of maximizing benefits and minimizing risks.

Lessons from meta-analyses of randomized clinical trials for analysis of distributed networks of observational databases

Networks of constellations of longitudinal observational databases, often electronic medical records or transactional insurance claims or both, are increasingly being used for studying the effects of medicinal products in real-world use. Such databases are frequently configured as distributed networks. That is, patient-level data are kept behind firewalls and not communicated outside of the data vendor other than in aggregate form. Instead, data are standardized across the network, and queries of the network are executed locally by data partners, and summary results provided to a central research partner(s) for amalgamation, aggregation, and summarization. Such networks can be huge covering years of data on upwards of 100 million patients. Examples of such networks include the FDA Sentinel Network, ASPEN, CNODES, and EU-ADR. As this is a new emerging field, we note in this paper the conceptual similarities and differences between the analysis of distributed networks and the now well-established field of meta-analysis of randomized clinical trials (RCTs). We recommend, wherever appropriate, to apply learnings from meta-analysis to help guide the development of distributed network analyses of longitudinal observational databases.

Risk of intracranial hemorrhage (RICH) in users of oral antithrombotic drugs: Nationwide pharmacoepidemiological study

Background

The risks of intracranial haemorrhage (ICH) associated with antithrombotic drugs outside clinical trials are gaining increased attention. The aim of this nationwide study was to investigate the risk of ICH requiring hospital admission in users of antithrombotic drugs.

Methods and findings

Data from the Norwegian Patient Registry and Norwegian Prescription Database were linked on an individual level. The primary outcome was incidence rates of ICH associated with use of antithrombotic drugs. Secondary endpoints were risk of ICH and fatal outcome following ICH assessed by Cox models. Among 3,131,270 individuals ≥18 years old observed from 2008 through 2014, there were 729,818 users of antithrombotic medications and 22,111 ICH hospitalizations. Annual crude ICH rates per 100 person-years were 0.076 (95% CI, 0.075–0.077) in non-users and 0.30 (95% CI, 0.30–0.31) in users of antithrombotic medication, with the highest age and sex adjusted rates observed for aspirin-dipyridamole plus clopidogrel (0.44; 95% CI, 0.19–0.69), rivaroxaban plus aspirin (0.36; 95% CI, 0.16–0.56), warfarin plus aspirin (0.34; 95% CI, 0.26–0.43), and warfarin plus aspirin and clopidogrel (0.33; 95% CI, 0.073–0.60). With no antithrombotic medication as reference, the highest adjusted hazard ratios (HR) for ICH were observed for aspirin-dypiridamole plus clopidogrel (6.29; 95% CI 3.71–10.7), warfarin plus aspirin and clopidogrel (4.38; 95% CI 2.71–7.09), rivaroxaban plus aspirin (3.82; 95% CI, 2.46–5.95), and warfarin plus aspirin (3.40; 95% CI, 2.99–3.86). All antithrombotic medication regimens were associated with an increased risk of ICH, except dabigatran monotherapy (HR 1.20; 95% CI, 0.88–1.65) and dabigatran plus aspirin (HR 1.79; 95% CI, 0.96–3.34). Fatal outcome within 90 days was more common in users (2,603 of 8,055) than non-users (3,228 of 14,056) of antithrombotic medication (32.3% vs 23.0%, p<0.001), and was associated with use of warfarin plus aspirin and clopidogrel (HR 2.89; 95% CI, 1.49–5.60), warfarin plus aspirin (HR 1.37; 95% CI, 1.11–1.68), aspirin plus clopidogrel (HR 1.30; 95% CI, 1.05–1.61), and warfarin (HR 1.19; 95% CI, 1.09–1.31). Increased one-year mortality was observed in users of antithrombotic medication following hemorrhagic stroke, subdural hemorrhage, subarachnoid hemorrhage, and traumatic ICH (all p<0.001). Limitations include those inherent to observational studies including the inability to make causal inferences, certain assumptions regarding drug exposure, and the possibility of residual confounding.

Conclusions

The real-world incidence rates and risks of ICH were generally higher than reported in randomized controlled trials. There is still major room for improvement in terms of antithrombotic medication safety (clinicaltrials.gov NCT02481011).

Empirical confidence interval calibration for population-level effect estimation studies in observational healthcare data

Observational healthcare data, such as electronic health records and administrative claims, offer potential to estimate effects of medical products at scale. Observational studies have often been found to be nonreproducible, however, generating conflicting results even when using the same database to answer the same question. One source of discrepancies is error, both random caused by sampling variability and systematic (for example, because of confounding, selection bias, and measurement error). Only random error is typically quantified but converges to zero as databases become larger, whereas systematic error persists independent from sample size and therefore, increases in relative importance. Negative controls are exposure-outcome pairs, where one believes no causal effect exists; they can be used to detect multiple sources of systematic error, but interpreting their results is not always straightforward. Previously, we have shown that an empirical null distribution can be derived from a sample of negative controls and used to calibrate P values, accounting for both random and systematic error. Here, we extend this work to calibration of confidence intervals (CIs). CIs require positive controls, which we synthesize by modifying negative controls. We show that our CI calibration restores nominal characteristics, such as 95% coverage of the true effect size by the 95% CI. We furthermore show that CI calibration reduces disagreement in replications of two pairs of conflicting observational studies: one related to dabigatran, warfarin, and gastrointestinal bleeding and one related to selective serotonin reuptake inhibitors and upper gastrointestinal bleeding. We recommend CI calibration to improve reproducibility of observational studies.

A study on indices of apixaban anticoagulation: A single-center prospective study

BACKGROUND

Depending on the characteristics of patients, the blood concentration of apixaban can unexpectedly increase, possibly leading to bleeding events. Anti-FXa activity reflects the apixaban blood concentration; however, measurement of this activity is both time-consuming and expensive. The current study aimed to evaluate the usefulness of routinely measured coagulation indices as future indicators of the efficacy and safety of apixaban.

METHODS

Eighteen nonvalvular atrial fibrillation patients administered apixaban (average, 52.5 days) were prospectively enrolled in our hospital. The prothrombin time (PT) and the activated partial thromboplastin time (APTT) were measured by using the Coagpia® Reagent kits.

RESULTS

The PT and the APTT increased significantly after the administration of apixaban (PT: p < 0.001, APTT: p < 0.001). While the apixaban plasma concentration by evaluating anti-FXa activity was not significantly correlated with the APTT after administration of apixaban, the concentration closely correlated with the PT (β = 0.765, p < 0.001) and the percentage change in the PT from before and after the administration of apixaban (β = 0.650, p = 0.005).

CONCLUSION

The usefulness of routinely monitoring PT in patients administered apixaban during the ordinary clinical medicine should be investigated further by large clinical trials.

[Hemorrhage under direct oral anticoagulants : Occurrence and treatment in intensive care patients]

The use of anticoagulants is associated with an increased risk of bleeding and nevertheless bleeding complications can be lifethreatening. The focus is on bleeding under direct oral anticoagulants (DOAC) because antidotes and specific measures are lacking for some DOACs. Furthermore, routinely carried out clotting tests cannot be used to determine the degree of anticoagulation under DOACs. Therefore, it becomes difficult to determine whether the coagulation inhibition effect is present. This article presents the treatment of hemorrhage in patients with DOACs in the intensive care unit. Further, the indications for DOACS and details of administration and monitoring are presented.

Sources of Safety Data and Statistical Strategies for Design and Analysis: Transforming Data Into Evidence

BACKGROUND

Safety evaluation is a key aspect of medical product development. It is a continual and iterative process requiring thorough thinking, and dedicated time and resources.

METHODS

In this article, we discuss how safety data are transformed into evidence to establish and refine the safety profile of a medical product, and how the focus of safety evaluation, data sources, and statistical methods change throughout a medical product's life cycle.

RESULTS

Some challenges and statistical strategies for medical product safety evaluation are discussed. Examples of safety issues identified in different periods, that is, premarketing and postmarketing, are discussed to illustrate how different sources are used in the safety signal identification and the iterative process of safety assessment. The examples highlighted range from commonly used pediatric vaccine given to healthy children to medical products primarily used to treat a medical condition in adults. These case studies illustrate that different products may require different approaches, and once a signal is discovered, it could impact future safety assessments.

CONCLUSIONS

Many challenges still remain in this area despite advances in methodologies, infrastructure, public awareness, international harmonization, and regulatory enforcement. Innovations in safety assessment methodologies are pressing in order to make the medical product development process more efficient and effective, and the assessment of medical product marketing approval more streamlined and structured. Health care payers, providers, and patients may have different perspectives when weighing in on clinical, financial and personal needs when therapies are being evaluated.

Signals of bleeding among direct-acting oral anticoagulant users compared to those among warfarin users: analyses of the post-marketing FDA Adverse Event Reporting System (FAERS) database, 2010-2015

Purpose

To analyze and compare the signals of bleeding from the use of direct-acting oral anticoagulants (DOACs) in the US Food and Drug Administration Adverse Event Reporting System (FAERS) database over 5 years.

Methods

Reports of bleeding and of events with related terms submitted to the FAERS between October 2010 and September 2015 were retrieved and then analyzed using the reporting odds ratio (ROR). The signals of bleeding associated with DOAC use were compared with the signals of bleeding associated with warfarin use utilizing the FAERS databases.

Results

A total of 1,518 reports linked dabigatran to bleeding, accounting for 2.7% of all dabigatran-related reports, whereas 93 reports linked rivaroxaban to bleeding, which accounted for 4.4% of all rivaroxaban-related reports. The concurrent proportion of bleeding-related reports for warfarin was 3.6%, with a total of 654 reports. The association of bleeding and of related terms with the use of all three medications was significant, albeit with different degrees of association. The ROR was 12.30 (95% confidence interval [CI] 11.65–12.97) for dabigatran, 15.61 (95% CI 14.42–16.90) for warfarin, and 18.86 (95% CI 15.31–23.23) for rivaroxaban.

Conclusions

The signals of bleeding varied among the DOACs, and the bleeding signal was higher for rivaroxaban and lower for dabigatran compared to that for warfarin.

Tromboc@t Working Group recommendations for management in patients receiving direct oral anticoagulants

BACKGROUND AND OBJECTIVES

In recent years, direct oral anticoagulants (DOACs) have become an alternative to vitamin K antagonists (VKA) for the prevention of stroke and systemic embolism in patients with non-valvular atrial fibrillation (NVAF) as well as for prevention and treatment of deep venous thrombosis. Pivotal trials have demonstrated non-inferiority and potential superiority compared to warfarin, which increases the options of anticoagulant treatment. In our setting, the Anticoagulant Treatment Units (ATUs) and Primary Care Centres (PCCs) play an important role in the education, follow-up, adherence control and management in special situations of anticoagulated patients. These considerations have motivated us to elaborate the present consensus document that aims to establish clear recommendations that incorporate the findings of scientific research into clinical practice to improve the quality of care in the field of anticoagulation.

MATERIAL AND METHODS

A group of experts from the Catalan Thrombosis Group (TROMBOC@T) reviewed all published literature from 2009 to 2016, in order to provide recommendations based on clinical evidence.

RESULTS

As a result of the project, a set of practical recommendations have been established that will facilitate treatment, education, follow-up and management in special situations of anticoagulated patients with ACODs.

CONCLUSIONS

Progressive increase in the use of DOACs calls for measures to establish and homogenise clinical management guidelines for patients anticoagulated with DOACs in ATUs and PCCs.

Pharmacological reversal of the direct oral anticoagulants-A comprehensive review of the literature

The direct oral anticoagulants (DOACs) are used for stroke prevention in atrial fibrillation (SPAF) and the prevention and treatment of venous thromboembolic disease (VTE). Although DOAC-associated bleeding events are less frequent as compared to vitamin K antagonists, there is significant concern surrounding physicians' ability to evaluate and manage DOAC-associated bleeding when it does occur. Idarucizumab is a specific reversal agent for dabigatran and is the agent of choice for dabigatran reversal in the setting of major bleeding or urgent surgery/procedures. There are no commercially available specific reversal agents for the direct Xa inhibitors. Although they have not been rigorously studied in DOAC-treated patients requiring urgent anticoagulant reversal, limited evidence from in vitro studies, animal bleeding models, human volunteer studies (in vivo and in vitro) and case series suggest that coagulation factor replacement with prothrombin complex concentrate (PCC) and activated PCC (FEIBA) may contribute to hemostasis. However, the safety and efficacy of these agents and the optimal dosing strategies remain uncertain.

Real-World Evidence: Useful in the Real World of US Payer Decision Making? How? When? And What Studies?

OBJECTIVES

To examine how real-world evidence (RWE) is currently perceived and used in managed care environments, especially to inform pharmacy and therapeutic (P&T) committee decisions, to assess which study factors (e.g., data, design, and funding source) contribute to RWE utility in decisions, and to identify barriers to consideration of RWE studies in P&T decision making.

METHODS

We conducted focus groups/telephone-based interviews and surveys to understand perceptions of RWE and assess awareness, quality, and relevance of two high-profile examples of published RWE studies. A purposive sample comprised 4 physicians, 15 pharmacists, and 1 researcher representing 18 US health plans and health system organizations.

RESULTS

Participants reported that RWE was generally used, or useful, to inform safety monitoring, utilization management, and cost analysis, but less so to guide P&T decisions. Participants were not aware of the two sample RWE studies but considered both studies to be valuable. Relevant research questions and outcomes, transparent methods, study quality, and timely results contribute to the utility of published RWE. Perceived organizational barriers to the use of published RWE included lack of skill, training, and timely study results.

CONCLUSIONS

Payers recognize the value of RWE, but use of such studies to inform P&T decisions varies from organization to organization and is limited. Relevance to payers, timeliness, and transparent methods were key concerns with RWE. Participants recognized the need for continuing education on evaluating and using RWE to better understand the study methods, findings, and applicability to their organizations.

Structure of prothrombin in the closed form reveals new details on the mechanism of activation

The clotting factor prothrombin exists in equilibrium between closed and open conformations, but the physiological role of these forms remains unclear. As for other allosteric proteins, elucidation of the linkage between molecular transitions and function is facilitated by reagents stabilized in each of the alternative conformations. The open form of prothrombin has been characterized structurally, but little is known about the architecture of the closed form that predominates in solution under physiological conditions. Using X-ray crystallography and single-molecule FRET, we characterize a prothrombin construct locked in the closed conformation through an engineered disulfide bond. The construct: (i) provides structural validation of the intramolecular collapse of kringle-1 onto the protease domain reported recently; (ii) documents the critical role of the linker connecting kringle-1 to kringle-2 in stabilizing the closed form; and (iii) reveals novel mechanisms to shift the equilibrium toward the open conformation. Together with functional studies, our findings define the role of closed and open conformations in the conversion of prothrombin to thrombin and establish a molecular framework for prothrombin activation that rationalizes existing phenotypes associated with prothrombin mutations and points to new strategies for therapeutic intervention.

Dabigatran in nonvalvular atrial fibrillation: from clinical trials to real-life experience

: Atrial fibrillation is the most common arrhythmia in over-midlife patients. In addition to systolic heart failure, cerebral thromboembolism represents the most dramatic complication of this rhythm disorder, contributing to morbidity and mortality. Traditionally, anticoagulation has been considered the main strategy in preventing stroke and systemic embolism in atrial fibrillation patients and vitamin K-dependent antagonists have been widely used in clinical practice. Recently, the development of direct oral anticoagulants has certainly improved the management of this disease, providing, for the first time, the opportunity to go beyond vitamin K-dependent antagonists limits. In the RE-LY trial, dabigatran 150 mg twice daily was superior to warfarin in the prevention of stroke or systemic embolism and dabigatran 110 mg twice daily was noninferior. Both doses greatly reduced hemorrhagic stroke, and dabigatran 110 mg twice daily significantly reduced major bleeding compared with warfarin. Based on these results, dabigatran, a direct thrombin inhibitor, was the first direct oral anticoagulant to receive the regulatory approval for nonvalvular atrial fibrillation patients. To date, a specific reversal agent has just been approved as an antidote for this molecule. This review provides a summary of randomized trials, postmarket registries and specific clinical-settings summary on dabigatran in nonvalvular atrial fibrillation.

Outcomes of Dabigatran and Warfarin for Atrial Fibrillation in Contemporary Practice: A Retrospective Cohort Study

BACKGROUND

Dabigatran (150 mg twice daily) has been associated with lower rates of stroke than warfarin in trials of atrial fibrillation, but large-scale evaluations in clinical practice are limited.

OBJECTIVE

To compare incidence of stroke, bleeding, and myocardial infarction in patients receiving dabigatran versus warfarin in practice.

DESIGN

Retrospective cohort.

SETTING

National U.S. Food and Drug Administration Sentinel network.

PATIENTS

Adults with atrial fibrillation initiating dabigatran or warfarin therapy between November 2010 and May 2014.

MEASUREMENTS

Ischemic stroke, intracranial hemorrhage, extracranial bleeding, and myocardial infarction identified from hospital claims among propensity score-matched patients starting treatment with dabigatran or warfarin.

RESULTS

Among 25 289 patients starting dabigatran therapy and 25 289 propensity score-matched patients starting warfarin therapy, those receiving dabigatran did not have significantly different rates of ischemic stroke (0.80 vs. 0.94 events per 100 person-years; hazard ratio [HR], 0.92 [95% CI, 0.65 to 1.28]) or extracranial hemorrhage (2.12 vs. 2.63 events per 100 person-years; HR, 0.89 [CI, 0.72 to 1.09]) but were less likely to have intracranial bleeding (0.39 vs. 0.77 events per 100 person-years; HR, 0.51 [CI, 0.33 to 0.79]) and more likely to have myocardial infarction (0.77 vs. 0.43 events per 100 person-years; HR, 1.88 [CI, 1.22 to 2.90]). However, the strength and significance of the association between dabigatran use and myocardial infarction varied in sensitivity analyses and by exposure definition (HR range, 1.13 [CI, 0.78 to 1.64] to 1.43 [CI, 0.99 to 2.08]). Older patients and those with kidney disease had higher gastrointestinal bleeding rates with dabigatran.

LIMITATION

Inability to examine outcomes by dabigatran dose (unacceptable covariate balance between matched patients) or quality of warfarin anticoagulation (few patients receiving warfarin had available international normalized ratio values).

CONCLUSION

In matched adults with atrial fibrillation treated in practice, the incidences of stroke and bleeding with dabigatran versus warfarin were consistent with those seen in trials. The possible relationship between dabigatran and myocardial infarction warrants further investigation.

PRIMARY FUNDING SOURCE

U.S. Food and Drug Administration.

Management and outcome of gastrointestinal bleeding in patients taking oral anticoagulants or antiplatelet drugs

BACKGROUND

Non-vitamin K dependent oral anticoagulants (NOACs) significantly decrease overall major bleeding rates compared with vitamin K antagonists (VKAs) but there is conflicting evidence regarding the relative risk of gastrointestinal bleeding. Since data regarding the types, the management, and the outcome of NOAC-associated gastrointestinal bleeding are scarce, we aimed to fill this gap by comparing cases of gastrointestinal bleeding associated with NOAC, VKA, or antiplatelet therapy.

METHODS

All major gastrointestinal bleeding events documented in the prospective Dresden NOAC registry were identified, and bleeding location, lesion type, endoscopic treatment, use of blood and coagulation factor transfusion, length of stay, and in-hospital mortality were compared with historical data from a large cohort of consecutive gastrointestinal bleeding patients.

RESULTS

In the 143 NOAC therapy cases, upper gastrointestinal tract bleeding was seen in 44.1%, lower gastrointestinal tract bleeding was seen in 42.0%, and no lesion could be identified in the remaining 14.0%. In contrast, upper gastrointestinal tract bleeding was commoner in the 185 VKA therapy cases (53.0%) and in the 711 antiplatelet therapy cases (68.1%). Among cases with upper gastrointestinal tract bleeding during VKA or antiplatelet therapy, 54.1% and 61.4% respectively presented with ulcers, compared with 27.0% for NOAC therapy. In contrast, hemorrhoid bleeding was the predominant lesion type for lower gastrointestinal tract bleeding with NOAC therapy, with a rate of 33.3%, compared with 10.6% with VKA therapy and 8.7% with antiplatelet therapy. NOAC-associated gastrointestinal bleeding resulted in comparatively low resource consumption, shorter hospitalization, and low in-hospital mortality (1.6%) compared with gastrointestinal bleeding historically seen with use of VKAs (in-hospital mortality 5.6%) or antiplatelet agents (in-hospital mortality 11.9%).

CONCLUSIONS

Gastrointestinal bleeding in NOAC recipients is different from that seen with VKA or antiplatelet therapy and has a better short-term prognosis.

New oral anticoagulants for stroke prevention in atrial fibrillation: impact of study design, double counting and unexpected findings on interpretation of study results and conclusions

Four recently introduced new oral anticoagulants (dabigatran, rivaroxaban, apixaban and edoxaban) have been shown to be at least as efficacious and safe as warfarin for stroke prevention in patients with atrial fibrillation in their respective trials. The first three have been approved, while edoxaban is awaiting regulatory approval. Several guidelines have endorsed the approved new oral anticoagulants over warfarin because of their favourable risk-benefit ratio, low propensity for food and drug interactions, and lack of requirement for routine coagulation monitoring. In this invited review, we summarise the results of the four studies and discuss widely held conclusions. We take a step further and discuss how differences in study design, analysis plan, and unexpected events affect the interpretation of the study results. Finally, we take our re-interpretation of study results and discuss how they might impact clinical practice and anticoagulant choice for patients.

Patient outcomes using the European label for dabigatran

In the RE-LY trial dabigatran 150 mg twice daily (D150) showed significantly fewer strokes, and 110 mg (D110) significantly fewer major bleeding events (MBE) compared to well-controlled warfarin in patients with atrial fibrillation (AF). The European (EU) label currently recommends the use of D150 in AF patients who are aged < 80 years without an increased risk for bleeding (e.g. HAS-BLED score <3) and not on concomitant verapamil. In other patients, D110 is recommended. In this post-hoc analysis of the RE-LY dataset, we simulated how dabigatran (n=6,004) would compare to well-controlled warfarin (n=6,022) used according to the EU label. “EU label simulated dabigatran treatment” was associated with significant reductions in stroke and systemic embolism (hazard ratio [HR] 0.74; 95% confidence interval [CI] 0.60–0.91), haemorrhagic stroke (HR 0.22; 95%CI 0.11–0.44), death (HR 0.86; 95%CI 0.75–0.98), and vascular death (HR 0.80; 95%CI 0.68–0.95) compared to warfarin. Dabigatran was also associated with less major bleeding (HR 0.85; 95%CI 0.73–0.98), life-threatening bleeding (HR 0.72; 95%CI 0.58–0.91), intracranial haemorrhage (HR 0.28; 95%CI 0.17–0.45), and “any bleeds” (HR 0.86; 95%CI 0.81–0.92), but not gastrointestinal major bleeding (HR 1.23; 95%CI 0.96–1.59). The net clinical benefit was significantly better for dabigatran compared to warfarin. In conclusion, this post-hoc simulation of dabigatran usage based on RE-LY trial dataset indicates that “EU label simulated dabigatran treatment” may be associated with superior efficacy and safety compared to warfarin, and are in support of the EU label and the 2012 European Society of Cardiology AF guideline recommendations. Thus, adherence to European label/guideline use results in a clinically relevant benefit for dabigatran over warfarin, for both efficacy and safety.

Note: The editorial process for this paper was fully handled by Prof Christian Weber, Editor in Chief.

Unanswered questions and research priorities to optimise stroke prevention in atrial fibrillation with the new oral anticoagulants

This review article discusses the following, as yet unanswered, questions and research priorities to optimise patient management and stroke prevention in atrial fibrillation with the new direct oral anticoagulants (NOACs): 1. In patients prescribed a NOAC, can the anticoagulant effects or plasma concentrations of the NOACs be measured rapidly and reliably and, if so, can “cut-off points” between which anticoagulation is therapeutic (i.e. the “therapeutic range”) be defined? 2. In patients who are taking a NOAC and bleeding (e.g. intracerebral haemorrhage), can the anticoagulant effects of the direct NOACs be reversed rapidly and, if so, can NOAC-associated bleeding and complications be minimised and patient outcome improved? 3. In patients taking a NOAC who experience an acute ischaemic stroke, to what degree of anticoagulation or plasma concentration of NOAC, if any, can thrombolysis be administered safely and effectively? 4. In patients with a recent cardioembolic ischaemic stroke, what is the optimal time to start (or re-start) anticoagulation with a NOAC (or warfarin)? 5. In anticoagulated patients who experience an intracranial haemorrhage, can anticoagulation with a NOAC be re-started safely and effectively, and if so when? 6. Are the NOACs effective and safe in multimorbid geriatric people (who commonly have atrial fibrillation and are at high risk of stroke but also bleeding)? 7. Can dose-adjusted NOAC therapy augment the established safety and efficacy of fixed-dose unmonitored NOAC therapy? 8. Is there a dose or dosing regimen for each NOAC that is as effective and safe as adjusted-dose warfarin for patients with atrial fibrillation who have mechanical prosthetic heart valves? 9. What is the long-term safety of the NOACs?