Original Research
Monday, November 13, 2023
01:00 PM–02:30 PM
Abstract
Introduction: The ability to obtain a quantitative drug level for apixaban and rivaroxaban exists using drug-specific calibrated anti-Xa assays; however, no standard exists defining when to obtain direct oral anticoagulant (DOAC) concentrations or how to adjust medication regimens based on the results.
Research Question or Hypothesis: Describe the incidence of DOAC levels obtained, identify trends in prescribing DOAC levels in clinical practice, and qualitatively assess level appropriateness and actions taken based on level results.
Study Design: A qualitative, retrospective analysis was conducted using the electronic medical record to identify adult inpatients within a 10-hospital health system, from April 1, 2020, to November 1, 2022, with a calibrated apixaban or rivaroxaban anti-Xa level result.
Methods: The primary endpoint was the incidence of DOAC levels drawn as peaks. Secondary outcomes included the incidence of DOAC concentrations that prompted a dose change, association between dose or agent change and concentrations outside the on-therapy range, and association between indication for obtaining DOAC levels and resultant concentrations.
Results: One-hundred thirty-two calibrated anti-Xa levels were obtained in 101 inpatients during the study period, representing a level drawn in 0.48% of all apixaban and rivaroxaban orders. Eighty-three (63%) of patients were on apixaban. Only 42 (31.8%) of all levels were drawn appropriately as a peak. Seventeen (40.4%) of the peak levels were within the on-therapy range. Of the 25 levels outside the on-therapy range, 14 (56%) resulted in no change in therapy. For all levels drawn, 70 (53%) resulted in no change to therapy. Primary reasons to draw DOAC levels were extreme body weight (35%), treatment failure concerns (23%), bleeding concerns (18%), and drug interactions (14%).
Conclusion: DOAC concentrations are often drawn at inappropriate times and seldom influence a dose or agent change. Future research is needed to determine if DOAC concentrations may be clinically meaningful in a select subgroup of patients.
Presenting Author
Jennifer Osborn PharmD, BCCP, BCPSM Health Fairview - University of Minnesota Medical Center
Authors
Bailey Stevenson PharmD
M Health Fairview - University of Minnesota Medical Center