Frequency of and factors associated with underdosing of direct oral anticoagulants in patients with ischaemic stroke and atrial fibrillation

Abstract

IntroductionDirect oral anticoagulants (DOACs) are the first line of stroke prevention treatment in patients with non-valvular atrial fibrillation (NVAF). However, their inappropriate use is associated with increased risk of stroke, haemorrhagic complications, and mortality. The aim of this study is to analyse the factors associated with the non-prescription of anticoagulants and the underdosing of DOACs. MethodsWe conducted a descriptive study of a prospective registry of patients admitted to a stroke unit due to ischaemic stroke or transient ischaemic attack (TIA) during an 1-year period. We included consecutive patients with history of NVAF with indication for anticoagulant therapy (ACT), according to the CHA2DS2-VASc scale. We analysed demographic factors, exposure to vascular risk factors, kidney function, polymedication, and short- and medium-term stroke progression. ResultsData were obtained from 60 patients admitted due to TIA or ischaemic stroke, with a previous diagnosis of NVAF, of whom 13 (21.7%) were not receiving ACT. Of the remaining 47, 25 (53.2%) were under treatment with DOACs, 21 (44.7%) with vitamin K antagonists, and 1 (2.1%) with heparin. Among patients on DOACs, 8 (32%) were receiving inappropriately low doses, with no differences between drugs.Age (80.8 vs 74.9 years, p=.05) and female sex (75% vs 35.3%, p=.05) were associated with underdosing of DOACs. Paroxysmal atrial fibrillation (46.2% vs 14.9%, p<.005) and antiplatelet therapy (61.5% vs 8.5%, p<.005) were associated with non-prescription of ACT. ConclusionsInappropriate use of ACT, including underdosing, is frequent in our setting, occurring in up to one-third of patients admitted due to ischaemic stroke.