Presentation (CTI)

OBJECTIVES: X-linked hypophosphatemia (XLH) is a rare genetic disorder caused by a dominant loss-of-function mutation in the phosphate-regulating gene, affecting multiple body systems and often leading to musculoskeletal, neurological, auditory, and dental complications. Despite its impact on quality of life and recent advancements in treatment, research on patient experiences remains limited. Understanding these experiences is essential for aligning drug development programs with patient needs. It allows integration of the patient perspective into clinical trial design and guides the selection of clinical outcome assessments.
METHODS: A targeted literature search (2018-2025) identified signs, symptoms, impacts and burdens of XLH in adult patients. Priority was given to qualitative studies exploring patient experiences, with particular focus on research offering novel insights into the lived experiences of adults with XLH. Due to the scarcity of recent qualitative studies, findings from gray literature, including four market research insights, supplemented scientific data.
RESULTS: Of the 23 articles that met the eligibility criteria, 16 were included in the review and CDM development. An existing CDM summarizing concepts from a 2018 US interview study was identified. The most commonly reported symptoms included pain in multiple body parts, tiredness, muscle weakness, joint stiffness, abnormal gait, hearing loss and tinnitus. Adults with XLH reported pain as their most burdensome symptom. XLH significantly impacts daily life, affecting emotional well-being, work, finances, physical functioning, relationships, sleep, and placing burdens on caregivers and family members.
CONCLUSIONS: The CDM underscores XLH affects nearly all body systems, with far-reaching impacts on patients’ quality of life. Additional qualitative research with XLH patients is crucial to refine CDM and to formulate better drug development programs ultimately to achieve better patient experience. This work highlights the gap and reiterates the importance of incorporating patient perspectives to derive meaningful trial endpoints.