# The Mirage of Factor Equivalence: Examining the Complexities of Non‐Factor Therapies in Haemophilia

## TL;DR

This paper argues that using 'factor equivalence' to compare non-factor hemophilia therapies is flawed and suggests personalized lab tests instead.

## Contribution

The paper introduces the need for patient-specific assessments over generic factor equivalence benchmarks for non-factor hemophilia therapies.

## Key findings

- Factor equivalence estimates may not accurately reflect the true hemostatic potential of non-factor therapies.
- Patient-specific and context-specific lab assessments are needed to optimize novel hemostatic therapies.
- Relying on factor equivalence could lead to suboptimal treatment strategies in high-risk scenarios.

## Abstract

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.

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

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.