Underdosed Direct Oral Anticoagulants in Atrial Fibrillation Patients Reduce Stroke Severity and Improve Outcome

Abstract

Background and Purpose: Anticoagulant drugs, including vitamin K antagonist (VKA) and direct oral anticoagulants (DOACs), can reduce stroke severity and are associated with good functional outcomes. Some patients are prescribed lower-than-recommended doses of DOACs; whether these have similar effects has not been clarified. Methods: We retrospectively evaluated 1,139 consecutive ischemic stroke and transient ischemic attack patients with atrial fibrillation. Patients were divided into 5 groups according to their preceding anticoagulant drug therapies: no anticoagulant therapy (AC_n), undercontrolling VKA doses (VKA_uc), recommended, controlling VKA doses (VKA_rec), prescribed underdoses of DOAC (DOAC_ud), and recommended doses of DOAC (DOAC_rec). We investigated the associations between these anticoagulant drug therapies and patients’ initial stroke severity and 3-month outcomes. Results: Median National Institutes of Health Stroke Scale scores at admission were as follows: AC_n: 16, VKA_uc: 15, VKA_rec: 9, DOAC_ud: 5, and DOAC_rec: 7. When the AC_n group was used as a reference, regression analysis showed that VKA_rec (odds ratio [OR] 1.49, 95% confidence interval [CI] 1.01–2.21), DOAC_ud (OR 2.84, 95% CI: 1.47–5.66), and DOAC_rec (OR 1.83, 95% CI: 1.23–2.74) were associated with milder stroke severity, while VKA_uc was not. Median 3-month modified Rankin Scale scores were 2 in the DOAC_ud and DOAC_rec groups and 4 in all other groups. After adjusting for confounding factors, DOAC_ud (OR 3.14, 95% CI: 1.50–6.57) and DOAC_rec (OR 1.67, 95% CI: 1.05–2.64) were associated with good 3-month outcomes while VKA_uc and VKA_rec were not. Conclusions: In patients with atrial fibrillation, recommended doses and underdoses of DOACs reduced stroke severity on admission and were associated with good 3-month outcomes.