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Article History

Received: 25 January 2026

Accepted: 18 May 2026

First Online: 3 June 2026

Declarations

:

: The study was approved by the Swedish Ethical Review Authority (dnr 2023–00335-01). The requirement for informed consent was waived by the Swedish Ethical Review Authority. In accordance with the requirements of the Ethical Review Authority, written study information was sent by mail to all participants prior to study initiation, and participants were given the opportunity to decline participation through an opt-out consent procedure. Participants who did not decline participation were included in the study. Two patients declined participation and were therefore not included in the study.

: The authors have no conflicts of interest to declare.

: The study was registered in the Region Stockholm Clinical Studies Database prior to study initiation.

: In this retrospective study of patients with measured plasma concentrations of the anticoagulant edoxaban, 42% of samples showed concentrations below expected thresholds. No significant difference between concentrations was observed between patients with 30 mg and 60 mg dosing. Patients with low edoxaban concentration were more likely to have normal renal function. Additionally, off-label dose reductions and drug-drug interactions were observed in some cases with low concentrations. These findings suggest a potential role of therapeutic drug monitoring in selected patients to support individualized treatment, although larger studies are needed to confirm these observations.