The Mirage of Factor Equivalence: Examining the Complexities of Non-Factor Therapies in Haemophilia.

Background: This article provides a critical analysis of the 'factor equivalence' concept as applied to non-factor therapies (NFTs) for haemophilia, highlighting its limitations and clinical implications. Although factor equivalence estimates serve as a comparative tool for evaluating pro-coagulant effects across different therapies, they may fail to accurately represent the true haemostatic potential or clinical efficacy due to the diverse mechanisms of action of different molecules and patient-specific factors.

Aim: The article challenges the widespread adoption of factor equivalence as a universal benchmark to quantify the haemostatic potential of NFTs.

Discussion and conclusion: It advocates for patient- and context-specific laboratory assessments that reflect each therapy's unique pharmacological profile. This approach is particularly relevant to enhance personalised treatment strategies, especially in high-risk situations such as surgery or severe breakthrough bleeding, thereby optimising the use of novel haemostatic therapies.