Mortality in Patients With Atrial Fibrillation Receiving Nonrecommended Doses of Direct Oral Anticoagulants

Background: The recommended doses for direct oral anticoagulants (DOACs) to prevent stroke and systemic embolism (SE) in patients with atrial fibrillation (AF) are described in specific regulatory authority approvals. Objectives: The impact of DOAC dosing, according to the recommended guidance on all-cause mortality, stroke/SE, and major bleeding, was assessed at 2-year follow-up in patients with newly diagnosed AF. Methods: Of a total of 34,926 patients enrolled (2013 to 2016) in the prospective GARFIELD-AF (Global Anticoagulant Registry in the FIELD-AF), 10,426 patients received a DOAC. Results: The majority of patients (72.9%) received recommended dosing, 23.2% were underdosed, and 3.8% were overdosed. Nonrecommended dosing (underdosage and overdosage combined) compared with recommended dosing was associated with a higher risk of all-cause mortality (hazard ratio [HR]: 1.24; 95% confidence interval [CI]: 1.04 to 1.48); HR: 1.25 (95% CI: 1.04 to 1.50) for underdosing, and HR: 1.19 (95% CI: 0.83 to 1.71) for overdosing. The excess deaths were cardiovascular including heart failure and myocardial infarction. The risks of stroke/SE and major bleeding were not significantly different irrespective of the level of dosing, although underdosed patients had a significantly lower risk of bleeding. A nonsignificant trend to higher risks of stroke/SE (HR: 1.51; 95% CI: 0.79 to 2.91) and major bleeding (HR: 1.29; 95% CI: 0.59 to 2.78) was observed in patients with overdosing. Conclusions: In GARFIELD-AF, most patients received the recommended DOAC doses according to country-specific guidelines. Prescription of nonrecommended doses was associated with an increased risk of death, mostly cardiovascular death, compared with patients on recommended doses, after adjusting for baseline factors. (Global Anticoagulant Registry in the Field-AF [GARFIELD-AF]; NCT01090362)