Data from: Lifelong impact of X-Linked hypophosphatemia: results from a burden of disease survey

Context: X-linked hypophosphatemia (XLH) is characterized by excess FGF23,
hypophosphatemia, skeletal abnormalities, and growth impairment. We aimed
to understand the burden of disease of XLH across the life span. Methods:
Responses were collected from adults with XLH and parents/caregivers of a
child with XLH in an online survey, including multiple-choice and
open-ended questions on demographics, disease manifestations, treatment
history, assistive device use, and age-specific patient-reported outcomes
(PROs). Results: Data was collected from 232 adults with XLH (mean age
45.6 years, 76% female), and 90 parents/caregivers of a child with XLH
(mean age 9.1 years, 56% female). Mean age recalled for symptom onset was
3.2 years for adults and 1.3 years for children. When surveyed, nearly all
children (99%) and 64% of adults were receiving oral phosphate, active
vitamin D, or both. Prior participation in a trial investigating
burosumab, a fully human monoclonal antibody against FGF23, was reported
in 3% of children and 10% of adults; of these respondents, only one child
reported current treatment with burosumab at the time of the survey. Both
children and adults reported typical features of XLH including abnormal
gait (84% and 86%, respectively), bowing of the tibia/fibula (72% and
77%), and short stature (80% and 86%). Nearly all adults (97%) and
children (80%) reported bone or joint pain/stiffness. Adults reported a
history of fractures (n/N = 102/232; 44%), with a mean (SD) age at first
fracture of 26 (16) years. Adults reported osteophytes (46%), enthesopathy
(27%), and spinal stenosis (19%). Mean scores for PROs evaluating pain,
stiffness, and physical function were worse than population norms.
Analgesics were taken at least once a week by 67% of adults. Conclusions:
Despite the common use of oral phosphate and active vitamin D established
in the 1980s, children with XLH demonstrate a substantial disease burden,
including pain and impaired physical functioning that persists, as
demonstrated by similar responses reported in adults with XLH.