X-Linked Hypophosphatemia Management in Children: An International Working Group Clinical Practice Guideline.

Context: An International Working Group (IWG) developed new guidelines on the diagnosis, evaluation, management, and monitoring of X-linked hypophosphatemia (XLH) in children. Over the past 5 years, important advances have occurred in our understanding of the presentation, complications, and treatment of XLH.

Methods: A group of 50 international experts in XLH from Canada, the United States, Europe, Asia, and South America, along with methodology experts and a patient partner, held 18 teleconference meetings in 2023-2024. These meetings addressed key issues regarding diagnosing, evaluating, managing, and monitoring XLH in children. Two systematic reviews were conducted to examine the impact of burosumab compared to conventional therapy (phosphate salts and active vitamin D) or no therapy, and to assess the impact of conventional therapy vs no therapy on patient-important outcomes. The certainty of evidence was evaluated using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology. Additionally, narrative reviews were completed on XLH diagnosis and the role of genetic testing, and an expert clinical practice survey informed the monitoring recommendations.

Outcomes: An approach to establishing the diagnosis of XLH is presented. GRADEd recommendations were developed on treatment strategies for XLH in children. Monitoring recommendations, GRADEd as weak with very low certainty, were based on clinical practice survey of the IWG experts. The guidelines also addressed dental complications and proposed potential strategies to mitigate them.

Conclusion: These clinical practice guidelines provide an update of the current evidence on the diagnosis and management of XLH and provide a comprehensive guidance for multidisciplinary healthcare professionals involved in the care of children with XLH.