Quantifying time from last dose: do direct oral anticoagulant assays correlate with patient's reported last dose.

INTRODUCTION: In the absence of a patient's last direct oral anticoagulant (DOAC) dose time, best practice regarding preoperative DOAC cessation remains unclear. The aim of this study was to investigate, in a real-life patient cohort, if there was an association between subjective patient recall and objective DOAC assay titre.

METHODS/MATERIALS: A multicentre cohort study of consecutive surgical inpatients was conducted. DOAC assays were 'expected' if they satisfied both time and titre-based guidelines.

RESULTS: Patient-recalled last dose and DOAC assay was available in 285 individuals. DOAC assay titres correlated strongly with the expected levels based on a patient's reported last dose time(rho = 0.70, P value < 0.0001). However, underweight (<50 kg; P = 0.0339) and elderly (>80 years; P = 0.0134) were more likely to have an unexpectedly high assay titre.

CONCLUSIONS: A significant portion (∼25%) of patients had unexpected DOAC titres. DOAC levels can be clinically impactful in a significant percentage of patients, particularly in elderly and/or underweight.