Classification and characteristics of on-label and off-label apixaban use in Denmark and Sweden

Low-dose non-vitamin K antagonist oral anticoagulants in patients with atrial fibrillation

In the last decade, non-vitamin K antagonist oral anticoagulants (NOACs), a new generation of OACs, were introduced to prevent thromboembolism in patients with atrial fibrillation. Although vitamin K-dependent anticoagulants have long been used as OACs, their inherent disadvantage of considerable bleeding complications has limited their use. NOACs demonstrate similar or superior clinical outcomes to those of warfarin. Although strict dose reduction criteria are recommended for NOACs, low-dose NOACs are frequently utilized, especially in Asian patients. Low-dose NOACs have shown clinical outcomes similar to those of warfarin in randomized controlled trials (RCTs) and real-world studies. However, off-label low-dose NOACs have shown inconsistent results compared with standard-dose NOACs and warfarin. Therefore, strict dose reduction criteria for NOACs should be followed until RCTs confirm the issues associated with NOAC underdosing.

Comparison of Direct Oral Anticoagulants Versus Warfarin in Patients With Atrial Fibrillation and Bioprosthetic Heart Valves

There are limited data regarding direct oral anticoagulants (DOACs) for stroke prevention in patients with bioprosthetic heart valves (BHVs) and atrial fibrillation (AF). The objectives of this study were to evaluate the ambulatory utilization of DOACs and to compare the effectiveness and safety of DOACs versus warfarin in patients with AF and BHVs. We conducted a retrospective cohort study at a large integrated health care delivery system in California. Patients with BHVs and AF treated with warfarin, dabigatran, rivaroxaban, or apixaban between September 12, 2011 and June 18, 2020 were identified. Inverse probability of treatment-weighted comparative effectiveness and safety of DOACs compared with warfarin were determined. Use of DOACs gradually increased since 2011, with a significant upward in trend after a stay-at-home order related to COVID-19. Among 2,672 adults with BHVs and AF who met the inclusion criteria, 439 were exposed to a DOAC and 2233 were exposed to warfarin. For the primary effectiveness outcome of ischemic stroke, systemic embolism and transient ischemic attack, no significant association was observed between use of DOACs compared with warfarin (HR 1.19, 95% CI 0.96 to 1.48, p = 0.11). Use of DOACs was associated with lower risk of the primary safety outcome of intracranial hemorrhage, gastrointestinal bleeding, and other bleed (HR 0.69, 95% CI 0.56 to 0.85, p < 0.001). Results were consistent across multiple subgroups in the sensitivity analyses. These findings support the use of DOACs for AF in patients with BHVs.

Off-label Use of Direct Oral Anticoagulants Compared With Warfarin for Left Ventricular Thrombi

Importance

Left ventricular (LV) thrombi can arise in patients with ischemic and nonischemic cardiomyopathies. Anticoagulation is thought to reduce the risk of stroke or systemic embolism (SSE), but there are no high-quality data on the effectiveness of direct oral anticoagulants (DOACs) for this indication.

Objective

To compare the outcomes associated with DOAC use and warfarin use for the treatment of LV thrombi.

Design, Setting, and Participants

A cohort study was performed at 3 tertiary care academic medical centers among 514 eligible patients with echocardiographically diagnosed LV thrombi between October 1, 2013, and March 31, 2019. Follow-up was performed through the end of the study period.

Exposures

Type and duration of anticoagulant use.

Main Outcomes and Measures

Clinically apparent SSE.

Results

A total of 514 patients (379 men; mean [SD] age, 58.4 [14.8] years) with LV thrombi were identified, including 300 who received warfarin and 185 who received a DOAC (64 patients switched treatment between these groups). The median follow-up across the patient cohort was 351 days (interquartile range, 51-866 days). On unadjusted analysis, DOAC treatment vs warfarin use (hazard ratio [HR], 2.71; 95% CI, 1.31-5.57; P = .01) and prior SSE (HR, 2.13; 95% CI, 1.22-3.72; P = .01) were associated with SSE. On multivariable analysis, anticoagulation with DOAC vs warfarin (HR, 2.64; 95% CI, 1.28-5.43; P = .01) and prior SSE (HR, 2.07; 95% CI, 1.17-3.66; P = .01) remained significantly associated with SSE.

Conclusions and Relevance

In this multicenter cohort study of anticoagulation strategies for LV thrombi, DOAC treatment was associated with a higher risk of SSE compared with warfarin use, even after adjustment for other factors. These results challenge the assumption of DOAC equivalence with warfarin for LV thrombi and highlight the need for prospective randomized clinical trials to determine the most effective treatment strategies for LV thrombi.

Direct-Acting Oral Anticoagulants: A Resident-Based Workshop to Improve Knowledge and Confidence

Introduction

Direct-acting oral anticoagulant (DOAC) prescriptions have increased steadily since the first, dabigatran, was Food and Drug Administration-approved in 2010. They have multiple advantages over vitamin K antagonists including fixed dosing without coagulation lab monitoring, rapid onset and offset of action, and fewer drug and food interactions. Patient-specific dosing, administration education, adherence, and monitoring are critically important. Many providers are unfamiliar with these concepts and too often use DOACs for off-label indications or at off-label dosing. A DOAC workshop was created to address knowledge gaps and improve internal medicine resident prescribing confidence.

Methods

One author (Irsk Anderson) conducted four 1-hour DOAC workshops with 49 total internal medicine residents rotating on their outpatient clinical rotation between October 2018 and November 2019. Residents performed small-group learning around four DOAC-specific cases, followed by a large-group report-out session. The residents completed pre- and postworkshop multiple-choice questions (MCQs) to assess knowledge as well as a postworkshop DOAC confidence self-assessment.

Results

Resident knowledge, assessed by percentage of residents answering correctly, improved significantly for all four MCQs after completing the workshop (all p <.003). Resident confidence, assessed on a 5-point Likert scale, improved significantly for all five themes (p <.001). Overall resident satisfaction was high (M = 4.2 on a 5-point Likert scale) and 85% desired further DOAC training.

Discussion

A 1-hour DOAC workshop was feasible and improved internal medicine resident knowledge and self-confidence. Future work should assess behavior change and patient clinical outcomes.