Impact of different dose reduction criteria on dose assignment of current DOACs and related outcomes: an analysis from 4-year data of the ETNA-AF Europe programme
Authors: Diemberger I G O R , Schnabel R , Ameri P , Fronk E M , Chhabra R , Kirchhof P , De Caterina R 
Published: May 2024

Abstract

Background
Direct oral anticoagulants (DOACs) are the standard treatment for stroke prevention in patients with atrial fibrillation (AF). Pharmacological characteristics and dose reduction criteria of the four currently available DOACs are different. Several studies have reported frequent use of non-recommended doses of DOACs associated with worse clinical outcomes. Data from real-world studies, such as the edoxaban Treatment in routiNe clinical prActice (ETNA)-AF, may help assessing the size of this phenomenon and its impact on clinical outcomes.

Purpose
To evaluate the distribution of dose reduction criteria and explore associated outcomes in a large, unselected, real-world population using 4-year data from the ETNA-AF EU study.

Methods
The ETNA-AF EU is a prospective, observational, study to evaluate safety and effectiveness of edoxaban in patients with AF from Europe. Patients with available data regarding the SmPC dose reduction criteria of the four currently available DOACs were included. Patients with a creatinine clearance &lt;30 mL/min were excluded. Patients were classified by dose reduction criteria for the different DOACs (i.e., full dose for all [FULL], reduced dose for all [REDUCED], patients not included in previous groups [INTERMEDIATE]).

Results
We included 12,866 patients from the ETNA-AF EU study. According to the SmPC dose reduction criteria, the percentage of patients that would be eligible for a dose reduction in the ETNA population was highly heterogenous across different DOACS: 5.7% for apixaban, 16.8% for rivaroxaban, 23.8% for edoxaban and 52.9% for dabigatran. Moreover, differences in the dose reduction criteria included in each SmPC was reflected by the distribution of patients in the three pre-specified groups. Among the 11,003 assignable patients, 42.4% would receive a full dose, 5.1% would receive a reduced dose and the largest percentage, 52.5%, was in the INTERMEDIATE group, which would receive either a full or reduced dose of any DOAC depending on the selected agent. Of the patients included in the INTERMEDIATE group, 65.2% received a full dose of edoxaban due to its specific labelling. Interestingly, the INTERMEDIATE group included the vast majority of patients known to be at risk of adverse events: very elderly (i.e., ≥85 yrs; 76.5%), frail as per investigator (73.3%), history of previous stroke (60.4%) or history of bleeding (61.3%). Clinical outcomes at four years were significantly higher in both the INTERMEDIATE and the REDUCED groups compared to the FULL group, with the only exception of haemorrhagic stroke (Table).
Conclusion(s): According to the different dose reduction criteria of currently available DOACs, notable percentage of patients could receive either a full or a reduced dose depending on the DOAC chosen by the physician. Considering that the chosen dose of the DOAC has an impact on clinical outcomes, patients in the INTERMEDIATE group need careful assessment, which warrants further analysis.