Karine Briot

Context Musculoskeletal complications are the main manifestations in adults with X-linked hypophosphatemia (XLH). Enthesopathy significantly impairs quality of life. Objective To identify the risk factors associated with the development and progression of spinal enthesopathies in adults with XLH. Design and setting We conducted a retrospective study in the French Reference Center for Rare Diseases of the Calcium and Phosphate Metabolism. Patients Adults XLH patients with 2 EOS® imaging performed at least 2 years apart at the same center between June 2011 and March 2022. The progression of enthesopathies was defined as a new enthesopathy at least 1 intervertebral level in patients with or without presence of enthesopathy at baseline. Main outcome measures Demographic, treatment, PHEX mutation with the progression of enthesopathies. Results Fifty-one patients (66.7% of women, mean age 42.1 ± 13.4 years) underwent 2 EOS imaging with an average interval of 5.7 (± 2.31) years. Progression of spinal enthesopathies was observed in 27 (52.9%) patients. In univariate analysis, patients with a progression of spinal enthesopathies were significantly older (P < .0005), were significantly older at treatment initiation (P = .02), presented with dental complications (P = .03), received less frequently treatment during childhood with phosphate and/or vitamin D analogs (P = .06), and presented more frequently with hip osteoarthritis (P = .002) at baseline. In multivariate analysis, none of these factors was associated with a progression of spinal enthesopathies. Conclusion This study confirms the high proportion of patients with a progression of spinal enthesopathies. Age seems to be the main factor associated with progression.