X-Linked Hypophosphatemia Exacts Early, High Toll on Musculoskeletal System

By Reuters Staff

November 02, 2021

NEW YORK (Reuters Health) - Adults with X-linked hypophosphatemia (XLH) have high rates of musculoskeletal problems that start as early as age 20 years and gradually accumulate over the years, a new analysis confirms.

XLH is a rare inherited disorder characterized by low levels of phosphate in the blood, leading to lifelong and progressive musculoskeletal problems.

To describe the burden of musculoskeletal features and associated surgeries across the lifespan of adults with XLH, researchers evaluated data on 336 adults with XLH, including 127 participating in a clinical trial, 209 who completed an online survey, and a subgroup of 137 of the online survey participants with pain comparable to the clinical trial subjects.

In all three groups, 43% to 47% had a history of fracture, with the proportions increasing with age.

The overall prevalence of osteoarthritis topped 50% in all three groups, with a rate of 23% to 37% in younger adults aged 18 to 29 year old and increasing with age. Similar patterns were observed for osteophytes and enthesopathy.

"Hip and knee arthroplasty was reported even in adults in their 30s," Dr. Muhammad Kassim Javaid of the University of Oxford, in the U.K., and colleagues report in the Journal of Clinical Endocrinology & Metabolism.

There was a low prevalence of spinal stenosis, although rates increased with age.

More than half of adults in all three groups had two or more musculoskeletal features, with rates of 59.1%, 55.0%, and 61.3% in the clinical trial group, survey group, and survey pain subgroup, respectively.

"This is the first analysis to characterize the accumulation of XLH-related musculoskeletal features across the lifespan of adults with XLH," the researchers say.

The findings demonstrate that adults with XLH "bear a substantial burden of multiple musculoskeletal features, emerging decades earlier than in the general population," they conclude.

Four authors served as clinical investigators for one or more studies, including this study, sponsored by Ultragenyx Pharmaceutical Inc in partnership with Kyowa Kirin International plc. Ultragenyx markets burosumab, which is approved to treat XLH. Medical writing and editorial support were provided by OPEN Health Medical Communications, with funding from Kyowa Kirin International.

SOURCE: https://bit.ly/2XMGxe6 Journal of Clinical Endocrinology & Metabolism, online October 12, 2021.