ESPE Abstracts (2023) 97 P2-176

1Department of Paediatric Endocrinology and Diabetes, Birmingham Women’s and Children’s Hospital NHS Trust, Birmingham, United Kingdom. 2Institute of Applied Health Research, University of Birmingham, Birmingham, United Kingdom. 3Department of Pediatric Nephrology, Hospital Sant Joan de Deu, Barcelona, Spain. 4Centre Hospitalier Universitaire (CHU) de Lyon, Hôpital Femme-Mère-Enfant, Lyon, France. 5University Medical Center Groningen, Department of Pediatric Endocrinology, University of Groningen, Groningen, Netherlands. 6Bristol Royal Hospital for Children, Bristol, United Kingdom. 7Department of Paediatric Endocrinology, Royal Manchester Children’s Hospital, Manchester, United Kingdom. 8Department of Paediatric Endocrinology, Alder Hey Children's NHS Foundation Trust, Liverpool, United Kingdom. 9Department of Pediatric Nephrology, Santa Lucia General University Hospital, Cartagena, Spain. 10Centre Hospitalier Universitaire (CHU) de Lille, Lille, France. 11Department of Nephrology, Great Ormond Street Hospital, London, United Kingdom. 12Assistance Publique Hôpitaux de Paris, Université Paris Saclay, Bicêtre Paris-Saclay Hospital, Le Kremlin Bicêtre, France. 13Department of Pediatric Nephrology, Virgen de las Nieves Universitary Hospital, Granada, Spain. 14Department of Pediatric Nephrology, Vall d´Hebron Universitary Hospital, Vall d´Hebron Institut de Recerca, Barcelona, Spain. 15Department of Pediatric Endocrinology and Diabetes, Charité Universitätsmedizin Berlin, Berlin, Germany. 16XLH Belgium (Belgium X-Linked Hypophosphatemic Rickets [XLH] Patient Association), Waterloo, Belgium. 17Open Health, Marlow, United Kingdom. 18Medical Affairs, Kyowa Kirin International, Marlow, United Kingdom. 19Aparito, Wrexham, United Kingdom


Background: XLH is a rare, genetic, life-long disease caused by PHEX pathogenic variants. It is associated with progressive accumulation of musculoskeletal features and symptoms that evolve across the patient’s lifetime if untreated. Although the disease is well characterised in children and adults, there are limited data describing the health outcomes and experiences of adolescents, particularly at end of skeletal growth (EOSG), a crucial phase during transition to adulthood. To explore these unmet needs, a collaborative, patient-centric, mixed-methods protocol was developed to assess functionality and health-related QoL (HRQoL) in adolescents with XLH at EOSG, as well as caregiver perspectives.

Methods: My XLH (NCT05181839) is a 12-month, multicentre, non-interventional, observational, prospective study using a mixed-methods approach. Research questions and methodology were informed and designed collaboratively by patient-centred outcome research specialists, adolescents with XLH, caregivers, expert European physicians, and specialist technology providers. Descriptive analyses of quantitative (baseline characteristics via medical records, XLH symptoms via app, physical activity via wearable device and HRQoL via EQ-5D questionnaire) and qualitative data (interviews) will assess the experiences of adolescents and caregivers in the pre-index (before EOSG) and post-index (after EOSG) periods. Targets of 30 adolescents and 15 caregivers were considered sufficient to reflect diversity of opinions and experiences. The study setting is specialist centres in the United Kingdom, France, the Netherlands, Germany and Spain that treat adolescents with XLH with burosumab, an anti-fibroblast growth factor-23 monoclonal antibody therapy. The target population is adolescents aged 12–17 years with a genetically confirmed diagnosis of XLH treated with burosumab for ≥12 months and confirmed by their physician as approaching EOSG. Adolescents who are non-adherent to treatment (missing ≥2 injections of burosumab in the previous 6 months) and those scheduled for orthopaedic surgery during the study will be excluded. Data will be collected for 4 weeks before and 26 weeks after EOSG. Analyses will be conducted to describe characteristics, symptoms, activities, and experiences of adolescents during treatment pre- and post-EOSG (with comparisons over time between patients continuing and discontinuing treatment post-index). Caregivers will be interviewed about their experiences and support needs of adolescents.

Results: Recruitment started on 24 November 2021. As of 18 April 2023, 24 patients have been enrolled. Enrolment is due to be completed by end December 2023. Data analysis is planned to commence in 2024.

Conclusion: Our multistakeholder, mixed-methods research design in a rare disease offers an inclusive approach to better understand patient and caregiver experience.

Volume 97

61st Annual ESPE (ESPE 2023)

The Hague, Netherlands
21 Sep 2023 - 23 Sep 2023

European Society for Paediatric Endocrinology 

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