The potential impact of gene therapy on health-related quality of life (HRQoL) domains in haemophilia

Introduction: Haemophilia is an inherited bleeding disorder characterised by spontaneous bleeding, often leading to impaired health-related quality of life (HRQoL). Commonly used treatments include episodic and prophylactic treatment regimens. Gene therapies could soon become available, potentially creating a paradigm shift in patient management. Aim: This paper proposes hypotheses about the potential impact of gene therapy on HRQoL domains in haemophilia, and how these impacts might differ compared with existing treatments. Methods: An expert working group with 10 individuals experienced in haemophilia and HRQoL research was established to discuss potential impacts of gene therapy on HRQoL in general and for specific domains in haemophilia. As part of a one-day workshop, domains of three widely used patient-reported outcome (PRO) instruments were explored: The Haemo-QoL-A, the Patient Reported Outcomes, Burden and Experiences (PROBE), and the Haemophilia Activities List (HAL). Results: The group expected a greater improvement in HRQoL from gene therapy compared with existing treatments for the following domains: Physical/role functioning, worry, and consequences of bleeding (Haemo-QoL-A); haemophilia-related health and EQ-5D-5L (part of the PROBE); leg and arm function, and leisure activities (HAL). In contrast, the experts suggested that no change or potential deterioration might be observed for the emotional impact (HAL) and treatment concerns (Haemo-QoL-A) domains. Conclusions: Current PRO instruments in haemophilia have limitations when applied in the context of gene therapy, and no single instrument fully captures the relevant HRQoL domains. However, the PROBE and Haemo-QoL-A were considered as the most suitable existing instruments. As haemophilia treatments evolve, further research should examine the potential effectiveness of existing PRO instruments as compared to the development of novel PRO measures.