One-year retrospective analysis of anti-FXa apixaban and rivaroxaban levels demonstrates utility for management decisions in various urgent and nonurgent clinical situations

Abstract

Objectives: Quantification of direct oral anticoagulant (DOAC) plasma levels can guide clinical management, but insight into clinical scenarios surrounding DOAC-calibrated anti-FXa assays is limited.

Methods: Apixaban- and rivaroxaban-calibrated chromogenic anti-Xa assays performed over a 1-year period were retrospectively analyzed. Patient demographics, DOAC history, concomitant medications, and renal/liver comorbidities were obtained. Indications for testing and associated clinical actions were reviewed. Machine learning (ML) models predicting clinical actions were evaluated.

Results: In total, 371 anti-FXa apixaban and 89 anti-FXa rivaroxaban tests were performed for 259 and 67 patients in recurring urgent (acute bleeding, unplanned procedures) and nonurgent situations, including several scenarios not captured by existing testing recommendations (eg, drug monitoring, recurrent thromboembolic events, bleeding tendency). In urgent settings, andexanet reversal was guided by radiologic and clinical findings over DOAC levels in 14 of 32 instances, while 51% of apixaban patients qualified for nonreversal strategies through the availability of levels. Levels also informed procedure/intervention timing and supported management decisions when DOAC clearance or DOAC target levels were in question. The importance of clinical context was emphasized by exploratory ML models predicting particular clinical actions.

Conclusions: Although clinical situations are complex, DOAC testing facilitates clinical decision-making, including reversal, justifying more widespread implementation of these assays.

Keywords: DOAC; anti-Xa assay; anticoagulation; apixaban; bleeding; decision support; machine learning; reversal; rivaroxaban; therapeutic monitoring.