Prevalence and characteristics of paediatric X-linked hypophosphataemia in Australia and New Zealand: Results from the Australian and the New Zealand Paediatric Surveillance Units survey

Jessica L Sandy; Carlos Nunez; Benjamin J Wheeler; Craig Jefferies; Anne Morris; Aris Siafarikas; Christine P Rodda; Peter Simm; Andrew Biggin; Sonya Aum; Elizabeth J Elliot; Craig F Munns

doi:10.1016/j.bone.2023.116791

Prevalence and characteristics of paediatric X-linked hypophosphataemia in Australia and New Zealand: Results from the Australian and the New Zealand Paediatric Surveillance Units survey

Bone. 2023 Aug:173:116791. doi: 10.1016/j.bone.2023.116791. Epub 2023 May 30.

Authors

Affiliations

¹ Institute of Endocrinology and Diabetes, The Children's Hospital at Westmead, Australia; Paediatrics & Child Health, School of Clinical Medicine, University of New South Wales, Australia. Electronic address: JessSandy@gmail.com.
² Australian Paediatric Surveillance Unit, Australia; Discipline of Child and Adolescent Health, University of Sydney, Sydney, New South Wales, Australia.
³ Department of Women's and Children's Health, University of Otago, New Zealand.
⁴ Te Whatu Ora, Starship Children's Health, Auckland, New Zealand.
⁵ Department of Endocrinology and Diabetes, Perth Children's Hospital, Western Australia, Australia; Division of Paediatrics, Medical School and Telethon Kids Institute, University of Western Australia, Perth, Western Australia, Australia; Institute for Health Research, University of Notre Dame, Fremantle, Western Australia, Australia.
⁶ Australian Institute for Musculoskeletal Research, Melbourne, Victoria, Australia; Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia.
⁷ Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia; Department of Endocrinology and Diabetes, Royal Children's Hospital, Melbourne, Victoria, Australia; Centre for Hormone Research, Murdoch Children's Research Institute, Melbourne, Victoria, Australia.
⁸ Discipline of Child and Adolescent Health, University of Sydney, Sydney, New South Wales, Australia.
⁹ Child Health Research Centre, Faculty of Medicine, The University of Queensland, Australia; Department of Endocrinology and Diabetes, Queensland Children's Hospital, Brisbane, Queensland, Australia.

PMID: 37263386
DOI: 10.1016/j.bone.2023.116791

Abstract

Background: X-linked hypophosphataemia (XLH) is the most common heritable form of rickets. Prevalence data varies across the literature between 1 in 20,000 and 1 in 200,000 per population.

Methods: Australian and New Zealand Paediatric Surveillance Units collected cross-sectional data from paediatricians on existing cases to estimate prevalence and characteristics of paediatric XLH in Australia and New Zealand.

Results: Seventy-five cases in Australia and 18 cases in New Zealand were identified. Estimated minimum prevalence based on these cases was 1.33 (1.04-1.66) per 100,000 and 1.60 per 100,000 (95%CI 0.97-2.58) in Australia and New Zealand respectively, with actual prevalence likely higher due to incomplete ascertainment. Despite a family history in most cases, delayed diagnosis was common, with 49 % diagnosed after 2 years of age. Delayed diagnosis was more common in sporadic versus familial cases. Most common clinical characteristics included leg bowing (89 %), bone and joint pain (68 %), abnormal gait (57 %) and short stature (49 %). There was a significant burden of orthopaedic disease and surgeries and a high rate of complications of nephrocalcinosis and hyperparathyroidism (32 % and 20 % respectively). Additionally, while guidelines stress the importance of multidisciplinary care, many did not have access to recommended health professionals, with only 3 % seeing a psychologist and 68 % seeing a dentist. This is despite the high psychological burden of XLH and a significant proportion (41 %) of this cohort having dental issues (tooth abscess, dental capping, tooth extraction). There were two cases from NZ without data available. Of the 91 cases with data collected, 46 % were on burosumab therapy. Consistent with clinical trials, those on burosumab had a higher serum phosphate levels (p < 0.001) at most recent follow-up. Three cases reported cancellation of orthopaedic surgery due to improvement in lower limb deformity after commencement of burosumab.

Conclusion: These data describe the multisystem burden of disease for children with XLH with care impacted by delayed diagnosis and a lack of access to many health professionals, especially psychological support.

Keywords: Burosumab; Paediatric; Rickets; X-linked hypophosphataemia.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Australia / epidemiology
Child
Cross-Sectional Studies
Familial Hypophosphatemic Rickets* / drug therapy
Familial Hypophosphatemic Rickets* / epidemiology
Humans
New Zealand / epidemiology
Prevalence