Direct Oral Anticoagulant Transition Strategies Using Anti-Xa Concentrations Upon Intensive Care Unit Admission

Background: The increased utilization of oral factor Xa inhibitors (FXaI) has led to a growing interest in the clinical utility of FXaI-specific anti-Xa concentrations. Critically ill populations are at risk of bleeding secondary to FXaI accumulation in the setting of end-organ dysfunction. To mitigate this risk, an FXaI anti-Xa concentration-guided approach to transitioning between oral and parenteral anticoagulation has been explored. Objective: To compare the incidence of bleeding upon intensive care unit (ICU) admission between 2 different FXaI transition strategies: concentration versus non-concentration-guided. Methods: We performed a retrospective chart review of patients admitted between January 2019 and May 2022 with objective evidence of FXaI exposure within 48 hours preceding ICU admission. Patients were excluded if they were admitted to the ICU with a primary diagnosis related to a bleeding event, received a non-FXaI anticoagulant 48 hours preceding ICU admission, remained off anticoagulation during their ICU admission, or underwent surgical procedures. The primary outcome was the incidence of major bleeding within 5 days of ICU admission. Thromboembolic events were evaluated as a secondary endpoint. Results: A total of 433 patients (184 concentration-guided vs 249 non-concentration-guided) were included. There was no difference in major bleeding between groups (2.7% in concentration-guided vs 3.6% in non-concentration-guided; P = 0.79). Thromboembolic complications were similar between groups (1.6% in concentration-guided vs 2.0% in non-concentration-guided; P = 1.00) despite a longer time from last FXaI dose to anticoagulant transition in the concentration-guided group (29.9 hours vs 19.4 hours; P < 0.01). Conclusion and relevance: Use of FXaI concentrations to guide anticoagulation transition in the ICU had no impact on major bleeding events or thromboembolic complications. Further analyses are needed to validate FXaI concentration-guided strategies and solidify anti-Xa cutoffs to create a standardized approach to FXaI transitions in the critically ill patient population.