Retrospective study of clinical settings, indications and consequences of measurement of direct oral anticoagulant plasma levels in Northern Tasmania, Australia.

ABSTRACT

BACKGROUND: Routine monitoring of direct oral anticoagulant (DOAC) levels is not recommended but may be useful in certain clinical situations. There is a knowledge gap regarding the clinical use of DOAC levels in Australian hospitals. AIMS: To evaluate the clinical settings, indications and changes to anticoagulant management associated with DOAC levels in a tertiary hospital in Northern Tasmania, Australia. METHODS: Patients with one or more DOAC levels (dabigatran, rivaroxaban or apixaban) requested between January 2017 and December 2022 were identified. Retrospective chart review was performed to evaluate the clinical settings, indications, adequacy of request information and changes to clinical management associated with the measurement of DOAC levels. RESULTS: One hundred and twenty-nine DOAC measurements (54 rivaroxaban, 66 apixaban and nine dabigatran) were performed in 98 patients between January 2017 and December 2022. Annual requests for DOAC levels increased significantly between 2017 and 2019 and remained stable between 2020 and 2021 but declined in 2022. Overall, the most common indication for a DOAC level was renal impairment, followed by bleeding and recurrent thrombosis. Approximately 25% of requests were for acute bleeding with a reversal/haemostatic agent given in 45% of patients, while 10% were prior to urgent surgery. Measurement of DOAC levels was associated with a change in management in 50% of cases. 10% of requests did not specify anticoagulant history. CONCLUSION: Trends in requests for DOAC levels have changed over time. Clinician education regarding the importance of providing specific anticoagulant history is essential. Future prospective studies investigating the clinical utility of DOAC levels in different clinical settings are needed.