Musculoskeletal features in adults with X-linked hypophosphatemia: An analysis of clinical trial and survey data.

PURPOSE: To describe the burden of musculoskeletal features and associated surgeries across the lifespan of adults with X-linked hypophosphatemia (XLH). METHODS: Three groups of adults were analyzed: subjects of a clinical trial, participants in an online survey, and a subgroup of the online survey participants considered comparable to the clinical trial subjects (according to Brief Pain Inventory worst pain scores of ≥4). In each group, the adults were categorized by age: 18-29, 30-39, 40-49, 50-59, and ≥60 years old. Rates of five prespecified musculoskeletal features and associated surgeries were investigated across these age bands for the three groups. RESULTS: Data from 336 adults were analyzed. In all three groups, 43-47% had a history of fracture, with the proportions increasing with age. The overall prevalence of osteoarthritis was >50% in all three groups, with a rate of 23-37% in the 18-29-year-old group, increasing with age. Similar patterns were observed for osteophytes and enthesopathy. Hip and knee arthroplasty was reported even in adults in their 30s. Spinal stenosis was present at a low prevalence, increasing with age. The proportion of adults with ≥2 musculoskeletal features was 59.1%, 55.0%, and 61.3% in the clinical trial group, survey group, and survey pain subgroup, respectively. CONCLUSIONS: This analysis confirmed high rates of multiple musculoskeletal features beginning as early as age 20 years among adults with XLH and gradually accumulating with age.