Sarcopenia: a new issue in juvenile idiopathic arthritis. A study Protocol

The decrease in muscle function and mass is defined as sarcopenia. Known for a long time as an age-related disorder, sarcopenia is nowadays well recognized in childhood. Juvenile idiopathic arthritis (JIA), a chronic inflammatory joint disease may be associated with loss of skeletal mass.

This protocol aims to evaluate the prevalence rate of sarcopenia and its associated factors in JIA.

To evaluate the prevalence rate and factors associated with sarcopenia in juvenile idiopathic arthritis, we are enrolling 30 children with JIA and 30 healthy children aged between 4-and 16 years. Clinical data will report: age, sex, body mass index, disease duration, and therapeutic management. All participants will undergo the Whole-body Dual-energy X-ray absorptiometry to assess the skeletal muscle mass. The muscle strength will be measured using the handgrip dynamometer and adjusted to the body mass index. Data will be analyzed and compared to age and sex reference curves.

This study aims to detect sarcopenia in JIA children and identify subsequently the main associated factors. By collecting anthropometric data and extracting the main features of the disease, specific metrics will be extracted. Body composition will be obtained using the DXA scans, including appendicular lean mass and skeletal muscle mass. Muscle strength will also be assessed.

This study aims to assess sarcopenia in JIA patients, using the sarcopenia update definition. If we will provide conclusive results, it will be possible to better identify the associated factors of sarcopenia and to prevent children from this complication. Clinical trials registration NCT05291416.