Bone Abstracts

The study is aimed to evaluate body composition and bone status in adult patients with active juvenile idiopathic arthritis (JIA) untreated with tumor necrosis factor α inhibitors. Adult patients (12 males and 19 females) with JIA and 84 healthy age- and gender- matched controls were enrolled into the study. Body composition and areal bone mineral density (aBMD) at the lumbar spine, proximal femur, femoral neck, distal radius and total body were assessed using dual energy X-ray absorptiometry, and correlated with clinical characteristics of the disease and physical performance tests. Disease activity was assessed using high-sensitivity C-reactive protein (hsCRP) and disease activity score 28 (DAS 28). The study has complied with the World Medical Association Declaration of Helsinki regarding ethical conduct of research involving human subjects. In patients with active JIA (DAS 28, 6.36±0.64, hsCRP, 18.36±16.95 mg/l), aBMD at all measured sites, bone mineral content (BMC) and lean mass were reduced, and fat mass was increased in the JIA patients as compared with healthy controls. Significant negative correlations were observed between BMC and disease duration, use of glucocorticoids (GCs), and fat mass, respectively. A positive correlation was found between BMC and lean mass, and between the body fat fraction and the use of GCs. Using multiple linear regression analysis, lean mass was the only significant predictor of BMC of total body both in men and women, and of BMC of legs (only in men). Lean mass was also the only predicting factor of total proximal femur BMD and femoral neck BMD. No significant correlations have been determined among the body composition parameters and DAS 28 or hsCRP endpoints. In conclusion, in adult patients with active JIA, lean mass was the main determining factor of total body and leg BMC, and total proximal femur and femoral neck aBMD.