Retrospective Real World Evidence Study to Describe Characteristics and Outcomes in Dutch Patients Admitted to the Hospital With a Factor Xa Inhibitor-associated Bleeding Treated With Andexanet Alfa

The direct oral anticoagulants (DOAC) rivaroxaban and apixaban inhibit factor Xa (FXa) and are widely used in clinical practice, due to the ease of administration, lack of need for frequent monitoring and dose adjustment and an improved safety profile. However, reversal of the anticoagulant effect of these FXa inhibitors (FXai) can be acutely required in case of serious bleeding events, like intracranial hemorrhage (ICH).

Ondexxya® (andexanet alfa) has been approved and is available in the Netherlands since 2019. Andexanet alfa is a modified FXa with no coagulant activity. It has a high binding affinity to DOACs and can therefore be used as reversal agent against DOACs. However, andexanet alfa is not used in all Dutch centers. In some hospitals, instead of andexanet alfa, nonspecific agents are used to manage FXai-associated ICH bleeding, like four-factor prothrombin complex concentrate (4F-PCC).

Due to the on par position of andexanet alfa and 4F-PCC in the Dutch multidisciplinary antithrombotic guideline, there is no clear patient profiling for the use of andexanet alfa for Dutch clinicians.

The lack of randomized clinical trials comparing the efficacy and safety of andexanet alfa and 4F-PCC also does not help to provide clarity. There is real world evidence data available (Coleman et al. 2020; Cohen et al. 2022; Costa et al. 2022) but these studies uses data from the US and the UK, and consistently report a superior effectiveness of andexanet alfa over 4F-PCC. However, there is considerable variation in the reported effectiveness between these studies, with mortality rate ranging from 4% to 15.3%. Potentially, differences in methodology and sample size, in addition to patient populations and bleeding locations varying between analyses, have resulted in this variation. Additionally, anecdotal information indicates that in some cases andexanet alfa is administered after 4F-PCC fails.

Therefore, the aim of the present analysis is to characterize the patient population that received andexanet alfa in the Dutch healthcare system. Also, we aim to describe clinical outcomes in patients treated with andexanet alfa in daily clinical practice in the Netherlands.