Impaired quality of life in adults with X-linked hypophosphatemia and skeletal symptoms He ´ le ` ne Che 1 , Christian Roux 1,2,3 , Adrien Etcheto 2 , Anya Rothenbuhler 4 , Peter Kamenicky 4 , Agne ` s Linglart 4 and Karine Briot 1,2 1 Department of Rheumatology, French Reference Center for Genetic Bone Diseases, Cochin Hospital, Assistance Publique- Ho ˆ pitaux de Paris, 27 rue du Faubourg Saint Jacques, 75014 Paris, France, 2 INSERM U1153, Paris, France, 3 Paris-Descartes University, Paris, France and 4 INSERM U1169, Paris Sud University, Assistance Publique- Ho ˆ pitaux de Paris, French Reference Center for Rare Disorders of the Mineral Metabolism, Department of Endocrinology and Diabetology for Children, Bice ˆ tre Hospital, 78 rue du Ge ´ ne ´ ral Leclerc, 94270 Le Kremlin Bice ˆ tre, France Correspondence should be addressed to K Briot Email karine.briot@aphp.fr Abstract Objective: Adults with X-linked hypophosphatemia (XLH) may suffer from skeletal symptoms leading to functional disability. No data on their quality of life (QoL) have been reported so far. Our objectives were to evaluate the QoL and its determinants in XLH adults. Patients and methods: We conducted a prospective study in XLH adults, who consulted for musculoskeletal symptoms between 2013 and 2014. We assessed their QoL using HAQ, RAPID3 and SF36, and analysed the variables associated with low QoL. We compared their QoL to that of patients affected with axial spondyloarthritis (ax-SpA) (paired on age and gender), a rheumatologic disorder with a known low QoL. Results: Fifty-two XLH adults (37 women (71.1%); mean age 41.8G13.3 years) were included; 44 (84.6%) patients had an altered QoL. Increased age and presence of structural lesions were significantly associated with worse QoL (HAQ, RAPID3) (P!0.05). Presence of enthesopathies was significantly associated with worse RAPID3 (ORZ4.45 (1.09–18.29), PZ0.038). Treatment with phosphate supplements and vitamin D in XLH adults were significantly associated with a better SF36-mental component score (ORZ0.14 (0.03–0.57), PZ0.007 and ORZ0.26 (0.07–0.98), PZ0.047 respectively). QoL was significantly worse in XLH than in ax-SpA adults (VAS pain, SF36-PCS, RAPID3) (P!0.05). Conclusion: Our study showed i) QoL of XLH adults is altered and significantly worse than that of ax-SpA patients (VAS pain, SF36-PCS and RAPID3), ii) structural lesions and especially enthesopathies are associated with a worse QoL and iii) treatment using phosphate supplements and/or vitamin D is associated with a better mental health score. European Journal of Endocrinology (2016) 174, 325–333 Introduction X-linked hypophosphatemia (XLH), the most common heritable form of rickets or osteomalacia, is due to loss- of-function mutations in the phosphate-regulating gene with homologies to endopeptidase on the X chromosome (PHEX), which results in elevated blood levels of fibroblast growth factor 23 (FGF23), phosphate wasting, hypophosphatemia and decreased vitamin D hydroxylation in the kidney. XLH has an incidence of 3.9/100 000 live births and a prevalence of 4.8/100 000 (1). In children, phenotypic expression includes variable degrees of growth retardation, bone pain and deformities, impaired dental mineralisation, delayed walking, cranios- tenosis, waddling gait, leg bowing and rickets. Therapy with phosphate salts and vitamin D analogs aim at reducing bone pain, improving dentition, correcting leg deformities, improving adult height and decreasing the number of surgeries (2, 3). Initiation at early ages is recommended as the early initiation of treatment optimises final body height results (2, 3). European Journal of Endocrinology Clinical Study H Che and others Quality of life in X-linked hypophosphatemia 174 :3 325–333 www.eje-online.org Ñ 2016 European Society of Endocrinology DOI: 10.1530/EJE-15-0661 Printed in Great Britain Published by Bioscientifica Ltd.