Routine Therapeutic Drug Monitoring of Dabigatran: Experience at a Tertiary Center

Background: A liquid chromatography-mass spectrometry assay to determine plasma dabigatran concentrations has been available for routine clinical use at our tertiary institutions since 2017. The aim of the study was to describe (1) the use of the assay over time; (2) the indications for testing; and (3) subsequent dabigatran prescribing decisions. Methods: Patients for whom dabigatran concentrations were measured were identified using the laboratory database, and clinical data were extracted from the associated electronic health records. Results: There were 233 samples in 24 months. The use of dabigatran increased over time, with a mean (95% confidence interval) increase of +0.5 (0.3–0.7) samples per month. Dabigatran concentrations ranged from <1 to 1060 mcg/L. The main reasons for testing were uncertainty about impact on renal function and drug interactions (39%), to inform prescribing decisions after thromboembolic or bleeding events (21%), and for investigation following dose-adjustment (16%). Dabigatran dose was changed after 30% (68/233) of assay results. Conclusions: The clinical use of the dabigatran assay has increased, with almost one-third of results associated with a subsequent change in dabigatran prescribing.