Overview of Patient-Reported Outcomes in Haemophilia Gene Therapy.

Background: Three adeno-associated virus-based gene therapies for haemophilia have received regulatory approval in Western countries since 2022, yet commercial uptake has been slow. Traditional clinical endpoints - annualised bleeding rate and factor activity levels - document haemostatic efficacy, but fail to capture what matters most to patients. Both the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA) increasingly recognise patient-reported outcomes (PROs) as meaningful endpoints for regulatory and health technology assessment decisions. Summary: Narrative review of peer-reviewed literature in PubMed and Web of Science (2017-2026) covering PRO instruments, clinical trial evidence, cost-effectiveness analyses, and qualitative patient data in haemophilia gene therapy. Six trials have reported PRO data using a total of 12 different instruments, of which five principal measures of which five measures are central to the quality-of-life evidence: the disease-specific Haem-A-QoL and Haemo-QoL-A, the generic EQ-5D-5L, and the gene therapy-specific coreHEM Mental Health Outlook (coreHEM-MHO). Across all studies, gene therapy produced clinically meaningful improvements in quality of life. Total disease-specific quality-of-life scores improved by 6-15 points across trials - exceeding established clinically important difference thresholds - with the largest gains in the Treatment and Dealing with Haemophilia domains. EQ-5D-5L utility indices increased significantly in multiple trials. In the SPK-9001 long-term follow-up, durable Haem-A-QoL gains were confirmed through 156 weeks. The coreHEM-MHO, developed to capture psychological dimensions unique to gene therapy such as durability anxiety and disease identity adjustment, has been piloted in BENEGENE-2. Qualitative interviews documented profound reductions in treatment burden and improved daily functioning. Key Messages: PRO evidence consistently demonstrates that haemophilia gene therapy delivers quality-of-life benefits that extend well beyond what traditional clinical endpoints capture. These PRO-derived improvements are also the principal driver of gene therapy's economic value since cost-effectiveness models show substantial gains in health-related quality of life but negligible gains in life expectancy. Priorities include standardised coreHEM measurement, long-term registries, and ensuring certified haemophilia centres are equipped for systematic PRO follow-up.