A level-headed approach to measuring direct oral anticoagulants: A 2-year retrospective analysis of DOAC levels from a tertiary UK centre.

ABSTRACT

INTRODUCTION: Direct oral anticoagulants (DOAC) are commonly prescribed and measuring drug levels may be useful in a number of contexts. However, data on DOAC level measurement and their clinical utility in real-world studies are limited. METHODS: We carried out a 2-year retrospective cohort study of DOAC levels measured at our institution. RESULTS: One hundred and sixty-nine levels measured in 113 patients were included in the final analysis. Our patients had a median age of 69.9. AF was the commonest indication for anticoagulation. Median turnaround time for inpatient levels was 92 minutes. Median FXa inhibitor levels within 6 hours of last dose and following one half-life were similar to those described previously. However, the range of levels was wider than expected. Importantly, some levels remained in an on therapy range even after 3 half-lives. There was no correlation between dabigatran level and time from last dose. The reason for request varied with setting; 23 outpatient levels were to monitor drug efficacy, whereas 54 and 43 inpatient levels were collected in the context of bleeding and emergency surgery respectively. 60.3% of levels had an impact on clinical decision making. CONCLUSION: Our real-world study demonstrates that DOAC levels can be performed in a timely manner to influence clinical decision making. In addition, it suggests there is a wide variation in levels such that it can be difficult to predict in the real world. Overall, this supports the wider use of DOAC levels to help guide clinicians in managing patients taking these drugs.