Health-related quality of life in French pediatric patients with X-linked hypophosphatemia: real-world data from the International XLH Registry

X-linked hypophosphatemia (XLH) is a phosphate-wasting disorder caused by increased fibroblast growth factor 23 (FGF23); it leads to skeletal deformities, muscle weakness, and pain. In a pediatric phase 3 trial, the FGF23 inhibitor burosumab improved rickets severity and bone biochemistry. The current study characterizes health-related quality of life (HRQL) in children with XLH using real-world data collected at centers in France for the International XLH Registry from April 2017 to January 2024. Age-appropriate versions of the Pediatric Quality of Life Inventory were completed. Data from the first completion after registry entry were analyzed. Variation in scores by demographic, medical history, and treatment history variables was assessed using bivariate analysis. The data were collected from 96 children (59% female; mean age 8.1 [SD 4.4] yr); 82% were taking burosumab. Mean total, summary, and domain scores were similar in different age groups. Mean total score (74.2 [SD 14.1]), Psychosocial Health Summary (72.0 [16.8]), and Physical Health Summary (78.3 [12.3]) scores were lowest in patients aged 5-7 yr and highest in patients aged 13-17 yr (81.0 [13.3], 79.8 [14.1], and 83.1 [15.2]). The mean Psychosocial Health Summary score was lower than the Physical Health Summary score for all patients combined (77.8 [13.9] vs 81.7 [14.3]). Better total scores were associated with not currently taking phosphate/vitamin D analogs, better Psychosocial Health Summary scores with higher serum phosphate and not taking phosphate/vitamin D analogs, and better Physical Health Summary scores with lower serum PTH and currently taking burosumab. Patients with XLH who were taking burosumab at the time of PedsQL completion had better total and summary scores than children with other chronic musculoskeletal disorders. Children aged 5-7 yr had worse HRQL than a healthy Dutch sample. Overall, better HRQL was associated with higher serum phosphate levels and burosumab treatment.