Site-level variation in and practices associated with dabigatran adherence

Edoxaban for reducing the risk of stroke and systemic embolism in patients with non-valvular atrial fibrillation

INTRODUCTION

Oral anticoagulation is central to the management of patients with atrial fibrillation (AF) and at least one additional stroke risk factor. For decades, the vitamin K antagonists (e.g. warfarin) remained the only oral anticoagulant available for stroke prevention in AF. The non-vitamin K oral anticoagulants (NOACs) are now available, and these drugs include the direct thrombin inhibitors and factor Xa inhibitors. The latter class includes edoxaban, which has recently been approved for stroke prevention in AF by the United States Food and Drug Administration and the European Medicine Agency. In line with other NOACs, edoxaban avoids the many limitations of warfarin associated with variability of anticoagulation effect and multiple food and drug interactions.

AREAS COVERED

In this review, the currently available evidence on edoxaban in patients with non-valvular AF is discussed. The pharmacology, efficacy and safety, and current aspects of use of edoxaban in patients with non-valvular AF for stroke and thromboembolism prevention are reviewed.

EXPERT OPINION

Phase III trials on edoxaban for stroke prevention in non-valvular AF confirms non-inferiority of edoxaban compared to well-managed warfarin both in terms of efficacy and safety. Currently ongoing and future trials as well as real-world data are warranted to confirm its effectiveness and safety for chronic anticoagulation and improve evidence in other areas which are lacking evidence where NOAC use remains controversial.

Stroke associated with discontinuation of warfarin therapy for atrial fibrillation

OBJECTIVE

The objective of this study was to determine the association between warfarin discontinuation and stroke among patients with nonvalvular atrial fibrillation (NVAF).

RESEARCH DESIGN AND METHODS

This was a retrospective, observational study of adult NVAF patients (≥ 18 years) who were on warfarin in the Truven MarketScan commercial claims and encounters and Medicare supplemental and coordination of benefits databases (1 January 2008 to 30 June 2012). Warfarin discontinuation was defined as a gap of ≥ 45 days in warfarin prescription within 1 year after initiation. Patients who did and did not discontinue warfarin were matched at a 1:1 ratio using a propensity score method. Matched patients were followed for up to 1 year to determine risks of ischemic stroke, transient ischemic attack (TIA), and hemorrhagic stroke. A multivariate Cox proportional hazards model was used to further adjust for the effects of potential confounders.

RESULTS

A total of 27,000 patients were included. Patients who discontinued warfarin had higher rates of ischemic stroke compared to persistent patients (1.0 vs. 0.5 per 100 patient years, P < 0.01), but similar rates of TIA (1.2 vs. 0.9 per 100 patient years, respectively; P = 0.07) and hemorrhagic stroke (0.3 vs. 0.2 per 100 patient years, P = 0.31). After adjustment for potential confounders, warfarin discontinuation was significantly associated with increased risk of ischemic stroke (hazard ratio [HR]: 2.04; 95% confidence interval [CI]: 1.47-2.84), TIA (HR: 1.36; 95% CI: 1.04-1.78), and ischemic stroke or TIA (HR: 1.50; 95% CI: 1.20-1.87).

CONCLUSIONS

Warfarin discontinuation is associated with increased risk of ischemic stroke and TIA. Health care providers may need to take a more active role in the management of warfarin discontinuation and clinical outcomes, e.g., by considering newer anticoagulants with favorable risk-benefit profiles. Key limitations of the study include unavailability of important clinical factors and measures in claims data.

Use of non-vitamin K antagonist oral anticoagulants in atrial fibrillation patients: insights from a specialist atrial fibrillation clinic

BACKGROUND

Non-vitamin K antagonist oral anticoagulants (NOACs) are broadly preferable to vitamin K antagonists (VKAs) for stroke prevention in non-valvular atrial fibrillation (AF) given their overall net clinical benefit. We report an audit of the profile of OAC usage and adverse events in patients attending a specialist AF clinic.

METHODS

Patients attending our specialist AF clinic who were commenced on NOACs for SPAF between January 2013 and August 2014 were included and electronic medical records were retrospectively reviewed between August 2014 and November 2014, to collect demographic, clinical and outcome data. Outcomes included cerebrovascular and bleeding events, death, switching between NOACs or to VKA, dose changes, cessation of NOACs and the reasons for these. To provide perspective, descriptive comparisons were made with a historical cohort of warfarin users attending the specialist AF clinic prior to the introduction of NOACs.

RESULTS

We report data on 813 patients as follows: (i) 233 consecutive patients (mean (standard deviation) age 74 (10) years, 45.1% female) initiated on NOACs, with median (interquartile range) CHA2 DS2 -VASc score 3 (2-5) and HAS-BLED score 1 (1-2); and (ii) a historical cohort of 580 patients on warfarin (mean (SD) age 75 (10) years, 42.1% female) with broadly similar demographics. Overall, 54.5% (127/233) were started on rivaroxaban, 22.7% (53/233) on dabigatran and 22.7% on apixaban. Two patients experienced a transient ischaemic attack; 31 patients (13%) contributed to 37 documented bleeding events of which five bleeds (in four patients, 1.7%) were classified as major. There were seven deaths; cause of death was not available for three and the others were not related to NOACs. Eighteen (7.7%) patients switched NOACs, 2 (0.9%) patients switched to warfarin and 8 (3.4%) had their NOACs stopped. There were no ischaemic strokes in the NOAC cohort, compared with nine in the warfarin cohort, with a similar rate of major bleeding (1.7% for NOACs and 1.6% for warfarin). There were more gastrointestinal haemorrhages in the NOAC cohort (3.4% vs. 0.7% with warfarin).

CONCLUSION

In this specialist AF clinic, patients prescribed NOACs had a favourable adverse event profile with good efficacy for stroke prevention, with a low rate of cessation or switch to warfarin.

Direct-acting oral anticoagulants: pharmacology, indications, management, and future perspectives

In recent years, several direct-acting oral anticoagulants (DOAC) have become available for use in Europe and other regions in indications related to prophylaxis and treatment of venous and arterial thromboembolism. They include the oral direct thrombin inhibitor dabigatran etexilate (Pradaxa, Boehringer Ingelheim) and the oral direct FXa inhibitors rivaroxaban (Xarelto, Bayer HealthCare), apixaban (Eliquis, Bristol-Myers Squibb), and edoxaban (Lixiana/Savaysa, Daiichi-Sankyo). The new compounds have a predictable dose response and few drug-drug interactions (unlike vitamin k antagonists), and they do not require parenteral administration (unlike heparins). However, they accumulate in patients with renal impairment, lack widely available monitoring tests for measuring its anticoagulant activity, and no specific antidotes for neutralization in case of overdose and/or severe bleeding are currently available. In this review, we describe the pharmacology of the DOAC, the efficacy, and safety data from pivotal studies that support their currently approved indications and discuss the postmarketing experience available. We also summarize practical recommendations to ensure an appropriate use of the DOAC according to existing data. Finally, we discuss relevant ongoing studies and future perspectives.

Innovative designs of point-of-care comparative effectiveness trials

One of the provisions of the health care reform legislation in 2010 was for funding pragmatic clinical trials or large observational studies for comparing the effectiveness of different approved medical treatments, involving broadly representative patient populations. After reviewing pragmatic clinical trials and the issues and challenges that have made them just a small fraction of comparative effectiveness research (CER), we focus on a recent development that uses point-of-care (POC) clinical trials to address the issue of "knowledge-action gap" in pragmatic CER trials. We give illustrative examples of POC-CER trials and describe a trial that we are currently planning to compare the effectiveness of newly approved oral anticoagulants. We also develop novel stage-wise designs of information-rich POC-CER trials under competitive budget constraints, by using recent advances in adaptive designs and other statistical methodologies.