Risk of stroke in patients with prior VKA or DOAC: A population-based real-world registry analysis

Introduction: To date, risk assessment of suffering ischemic and hemorrhagic stroke in individuals under oral anticoagulation (OAC) is limited to hospital-based cohorts and patients with atrial fibrillation. Patients and methods: Through the combination of three individual datasets, (1) the population-based Tyrolean Stroke Pathway database, prospectively documenting all (unselected) stroke patients in the entire federal state of the Tyrol and (2) nation-wide prescription data, detailing each reimbursed prescription in Austria as well as (3) the Austrian Stroke Unit Registry, a nation-wide registry comprising data on all patients admitted to any of the 38 stroke units in Austria, we assessed risk of stroke in patients with prior oral anticoagulation and compared characteristics of patients taking direct oral anticoagulants and Vitamin-K-Antagonists. Results: In Austria, oral anticoagulant prescription reimbursements increased from 292,475 in 2015 to 389,407 in 2021. In the Tyrol, prior oral anticoagulation treatment was evident in 586 of 3861 (15.2%) patients with ischemic and 131 of 523 (25.0%) with hemorrhagic stroke, with 20% and 35% of those stroke patients respectively having prior oral anticoagulation due to other indications than non-valvular atrial fibrillation. Considering prescription rates, treatment with direct oral anticoagulants was associated with a reduced stroke risk compared to Vitamin-K-Antagonists, especially in ischemic (1.05% vs 0.62%; RR 0.59, p < 0.001) but also in hemorrhagic stroke, even if less pronounced (0.21% vs 0.14%; RR 0.68, p = 0.06). In Austria, prior intake of direct oral anticoagulants was associated with lower risk of suffering acute large vessel occlusion stroke (RR 0.79, p = 0.003). Discussion and conclusions: One in seven patients suffering ischemic and one in four suffering hemorrhagic stroke had prior oral anticoagulation treatment. Both ischemic and hemorrhagic strokes are less frequent in those with direct oral anticoagulant intake compared to those taking Vitamin-K-Antagonists. Establishment of clear standard operating procedures on how to best care for acute stroke patients with oral anticoagulation is essential.