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

X-linked hypophosphataemia is a phosphate-wasting disorder caused by increased fibroblast growth factor 23; it leads to skeletal deformities, muscle weakness and pain. The fibroblast growth factor 23 inhibitor burosumab improved rickets severity and bone biochemistry in a paediatric phase 3 trial. The current study characterises health-related quality of life in children with X-linked hypophosphataemia using real-world data collected at centres 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 analysed. Variation in scores by demographic, medical history and treatment history variables was assessed using bivariate analysis. Data are from 96 children (59% female; mean age 8.1 [SD 4.4] years); 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 years and highest in patients aged 13–17 years (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 analogues; better Psychosocial Health Summary scores with higher serum phosphate and not taking phosphate/vitamin D analogues; and better Physical Health Summary scores with lower serum parathyroid hormone and currently taking burosumab. Patients with X-linked hypophosphataemia 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 years had worse health-related quality of life than a healthy Dutch sample. Overall, better health-related quality of life is associated with higher serum phosphate levels and burosumab treatment.