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Bone Rep. 2016 May 13;5:158-162. doi: 10.1016/j.bonr.2016.05.004. eCollection 2016 Dec.

Effect of four monthly doses of a human monoclonal anti-FGF23 antibody (KRN23) on quality of life in X-linked hypophosphatemia.

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Department of Medicine, Houston Methodist Hospital, Houston, TX, USA.
Kyowa Hakko Kirin Pharma Inc., Princeton, NJ, USA.
Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA.
Duke Clinical Bone Laboratories, Duke University Medical Center, Durham, North Carolina, USA.
Shriners Hospital for Children, Montreal, Quebec, Canada.
Department of Pediatrics, University of California San Francisco, CA, USA.
Yale Center for X-Linked Hypophosphatemia, Yale University School of Medicine, New Haven, CT, USA.


X-linked hypophosphatemia (XLH) is characterized by lower extremity deformities that lead to bone and/or joint pain that result from decreased renal tubular reabsorption leading to hypophosphatemia caused by elevated levels of fibroblast growth factor 23 (FGF23).


Validate the use of SF-36v2 Health Survey (SF-36v2) and the Western Ontario and McMaster Osteoarthritis Index (WOMAC) to measure previously unstudied health-related quality of life (HRQoL) in XLH patients and determine the change in HRQoL before and after treatment with KRN23, a human monoclonal anti-FGF23 antibody.


Twenty-eight adult outpatients with XLH received up to four doses of KRN23 administered subcutaneously every 28 days. General HRQoL was measured with the SF-36v2 and condition-related HRQoL with the WOMAC at baseline and study endpoint as a secondary outcome of a Phase 1/2, open-label, multicenter, dose-escalation trial.


Testing for scale discriminant validity and convergent-divergent validity supported the use of these scales in the assessment of HRQoL in XLH. Both instruments indicated impairment of physical function at baseline with all mean scores showing a trend to improved health at study endpoint compared to baseline. When corrected for multiple comparisons, the score for Role Limitations due to physical health on the SF-36v2 which measures the patient's perception of their own chronic functional impairments due to poor physical health remained significantly improved (P < 0.05), increasing to the mean score of US adults. For the WOMAC, Physical Functioning and Stiffness scores were significantly improved (P < 0.05).


KRN23 administration was associated with significantly improved patient perception of their Physical Functioning and Stiffness due to their disease. This study demonstrates that the SF-36v2 and WOMAC are valid tools for assessing HRQoL in XLH.


Fibroblast growth factor 23 (FGF23); HRQoL, health-related quality of life; Health-related quality of life; KRN23; MIC, Minimally Important Change; PRO, patient reported outcomes; Rickets; WOMAC, Western Ontario and McMaster Osteoarthritis Index; X-linked hypophosphatemia

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