Retrospective and Prospective Disease Progression and Quality of Life in XLH

There is limited empirical data documenting disease progression and impact on quality of life for patients with X-linked hypophosphatemia (XLH). This study seeks to investigate the impact of XLH in adults living in the UK retrospectively and prospectively over a 12 month period, using qualitative interviews, SEIQoL-DW, EQ-5D-5L, SF36 quality of life tools. XLH is a rare, genetic, chronically debilitating and deforming condition (www.nice.org.uk/guidance/HST8). XLH is characterised by renal phosphate wasting, hypophosphatemia and defective bone mineralisation. The incidence of XLH is reported to be between 1:20,000 and 1:25,000 live births. In the UK, it is estimated that there are around 250 paediatric XLH patients and around 2,500 adult XLH patients (Delmestri,et al \[Unpublished report\]2018). The clinical phenotype of XLH is varied amongst patients, even among affected members of the same family. This can range from no signs or symptoms, slow growth in children, short stature, bone abnormalities that can affect movement and result in pain, bowed legs and knocked knees (where lower legs are positioned at an outward angle), tooth abscesses and excessive dental caries and hearing loss (adult patients only). This study will recruit 36 adults living with XLH, who are aged 28 years or over and living in the UK. The study will be advertised by the Sponsor and funder Medialis Ltd and via the patient organisation Metabolic Support UK. All study activities will take place via tele-visits and online questionnaires. The study will last approximately 2 years, allowing for one-year recruitment and a further 12 months to conduct all study visits.