Disease Trajectories and Lived Experiences of Patients with X-Linked Hypophosphatemia in Taiwan: A Qualitative Study

X-linked hypophosphatemia (XLH) is a rare, lifelong disorder of renal phosphate wasting that typically presents in childhood with skeletal deformities, growth retardation, and functional impairment, although these features may be less pronounced in milder cases. The disease persists into adulthood with chronic pain, mobility limitations, and psychosocial challenges. While pediatric XLH has been well described internationally, the lifelong disease journey in Taiwan remains poorly characterized. We conducted a multicenter qualitative study using semi-structured, in-depth interviews between July 2024 and January 2025 at three major medical centers, enrolling 15 patients with a clinical diagnosis of X-linked hypophosphatemia (genetically confirmed in a subset): eight pediatric patients (aged ≥5 yr) interviewed with caregivers and seven adults interviewed independently. Interviews (~60 min) explored diagnostic pathways, treatment experiences, disease burden, and support needs; transcripts were analyzed thematically. Participants commonly reported delayed or missed diagnosis, with early symptoms such as bowed legs and short stature often misattributed to nutritional or growth-related issues, leading to late referral to specialist care. Oral phosphate supplementation and active vitamin D (Pi/D) were the predominant treatments; however, frequent dosing, poor palatability, and gastrointestinal side effects contributed to low adherence. Many adults had discontinued therapy, and 12 patients underwent corrective limb surgery, mainly during childhood or adolescence. Across the life course, patients experienced chronic bone pain, reduced mobility, and insufficiency fractures, as well as psychosocial burdens including anxiety, low self-esteem, social withdrawal, and caregiver stress, often compounded by guilt related to hereditary transmission. Patients and caregivers emphasized unmet needs in disease education, transition from pediatric to adult care, peer support, and interest in novel therapies such as burosumab. These findings highlight substantial lifelong disease burden among patients with XLH in Taiwan and underscore the need for earlier diagnosis, multidisciplinary care, and improved access to emerging therapies.