Apixaban and Rivaroxaban Anti-Xa Level Monitoring Versus Standard Monitoring in Hospitalized Patients With Acute Kidney Injury

Background: Oral direct factor Xa inhibitors (FxaIs) are renally eliminated; thus, acute kidney injury (AKI) may increase the risk for drug accumulation and bleeding. There is minimal data describing the effects of AKI on FxaI anti-Xa levels or clinical outcomes. Objective: To compare anti-Xa level monitoring with standard monitoring in patients who experience AKI on apixaban or rivaroxaban. Methods: This retrospective study included patients admitted within a large hospital system from May 2016 to October 2020. Patients were included if they received apixaban or rivaroxaban prior to AKI. Patients were stratified into 1 of 2 groups: those with anti-Xa level monitoring or those who received standard monitoring. The primary outcome was major bleeding as defined by the International Society of Thrombosis and Haemostasis. Results: A total of 196 patients were included in the final analysis. Major bleeding occurred in 2 patients who received anti-Xa level monitoring, compared with 14 patients who received standard monitoring (2.1% vs 14%; P < 0.01). Variables identified as predictors of major bleeding included a documented history of liver disease (adjusted odds ratio = 3.17; 95% CI = 1.04-9.67; P = 0.04) and antiplatelet use (adjusted odds ratio = 4.18; 95% CI = 1.28-13.7; P = 0.02). Conclusion and Relevance: This is the first study to demonstrate that anti-Xa level monitoring was associated with a significant reduction in major bleeding compared with standard monitoring in patients with AKI who received apixaban or rivaroxaban. The optimal management of antithrombotic medications in patients with AKI and recent exposure to an FxaI requires further investigation.