Assessment of sarcopenia in young patients with inflammatory arthritis: a cross-sectional study

Sarcopenia is a disease characterized by decreasing muscle mass and strength or performance. The prevalence of sarcopenia in rheumatic diseases has been evaluated in single diseases using various diagnostic approaches, generating conflicting data. The study aims to investigate sarcopenia prevalence in young adults with inflammatory arthritis (IA) and to detect factors associated with low muscle mass and strength. The single-center, cross-sectional study included 138 young adults with IA. Dynamometry with a Jamar hand dynamometer was used to determine handgrip strength. Thresholds for reduced muscle strength were < 27 kg for males and < 16 kg for females. To determine skeletal mass index (SMI), dual photon X-ray absorptiometry (DXA) was done with such cut-off points < 5.67 kg/m² in females and < 7.0 kg/m² in males. Patients with both reduced muscle mass and strength were considered as sarcopenic. Logistic regression analyses estimated between sarcopenia and associated factors. Statistical significance was defined as a p-value < 0.05. The prevalence of sarcopenia was about 47% in all IA and was significantly different between juvenile idiopathic arthritis (JIA), spondyloarthritis (SpA), and rheumatoid arthritis (RA) groups (p = 0.006). At multivariable analysis, body mass index (BMI) (OR 0.84; CI 95% 0.72-0.86, p = 0.02), bone mineral density (BMD) at femur neck (OR 0.01; CI 95% 0.001-0.268, p = 0.01), 25-hydroxyvitamin D (25(OH)D) (OR 0.96; CI 95% 0.93-0.98, p = 0.001), and disability by Health Assessment Questionnaire (HAQ) (OR 14.54; CI 95% 4.92-51.77, p < 0.001) were associated with a significantly increased risk of sarcopenia. The results of our study demonstrate a high prevalence of sarcopenia among young patients with IA. In these participants, lower BMI, lower BMD, 25(OH)D concentration, and higher HAQ were linked to sarcopenia.