Abstract
Preventing thromboembolic events, while minimizing bleeding risks, remains challenging
when managing patients with atrial fibrillation (AF). Several factors contribute to
current dosing patterns of nonvitamin K antagonist oral anticoagulants (NOACs), including
patient characteristics, comorbidities, and physician judgment. Application of NOAC
doses inconsistent with the drug labels may cause patients to receive either subtherapeutic
(increasing stroke risk) or supratherapeutic (increasing bleeding risk) anticoagulant
levels. In clinical practice, under- or over-dosing of NOACs in patients with AF is
not uncommon. This analysis of prospective and retrospective registry and database
studies on NOAC use in patients with AF (with at least 250 patients in each treatment
arm) showed that under-dosing may be associated with reduced effectiveness for stroke
prevention, with similar or even increased bleeding than with the standard dose. This
may reflect underlying conditions and patient factors that increase bleeding despite
NOAC dose reduction. Such factors could drive the observed overuse of reduced NOAC
dosages, often making the prescription of reduced-dose NOAC an intentional label deviation.
In contrast, over-dosing more likely occurs accidentally; instead of providing benefits,
it may be associated with worse safety outcomes than the standard dose, including
increased bleeding risk and higher all-cause mortality rates. This review summarizes
the main findings on NOAC doses usually prescribed to patients with AF in clinical
practice.
Keywords
anticoagulants - atrial fibrillation - stroke
