Factors associated with impaired physical functionality in X-linked hypophosphatemia

Area of Science:

• Medical Genetics
• Metabolic Bone Disease
• Rheumatology

Background:

• X-linked hypophosphatemia (XLH) is a rare genetic disorder causing impaired bone mineralization and chronic hypophosphatemia.
• Current XLH treatments focus on biochemical normalization, but physical function and quality of life (QoL) often remain suboptimal.
• The relationship between physical function, QoL, and disease factors in XLH requires further investigation.

Purpose of the Study:

• To investigate the association between physical functionality, quality of life, and chronic pain, muscle mass, and biochemical abnormalities in patients with XLH.
• To identify key factors contributing to functional deficits and reduced QoL in XLH patients.
• To evaluate the impact of muscle mass, muscle strength, and pain on daily activity limitations.

Main Methods:

• An observational, cross-sectional study involving 30 patients with XLH.
• Assessment of clinical records, biochemical parameters (FGF23, phosphate levels), and QoL using SF36v.2 and WOMAC surveys.
• Measurement of appendicular lean mass (ALM), muscle strength (quadriceps muscle isometric strength - QMS), and physical performance (6-Minute Walk Test - 6MWT).
• Pain assessment using Brief Pain Inventory, Visual Analog Scale, and Doleur Neuropathique-4 scales.

Main Results:

• All participants exhibited significant functional deficits, chronic pain, and reduced QoL.
• Limitations in daily activities were strongly associated with higher pain severity, decreased ALM, lower QMS, and reduced 6MWT distance (p < .05).
• No significant association was found between functional variables and FIM scale, phosphate levels, FGF23, or conventional treatment exposure.

Conclusions:

• Impaired physical functionality in XLH is primarily linked to reduced muscle mass, decreased muscle strength, and severe chronic pain.
• Optimizing biochemical control alone is insufficient; patient care must incorporate pain management and comprehensive physical rehabilitation.
• Addressing pain and muscle deficits is crucial for improving physical function and QoL in XLH patients.