Longitudinal evaluation of bone mass in adolescents and young adults with juvenile idiopathic arthritis: the role of bone mass determinants in a large cohort of patients

Abstract

Background: There are very few data evaluating prospectively the bone mass and quality determinants using dual energy X-ray absorptiometry (DXA), peripheral quantitative computed tomography (pQCT), and ultrasound (US) in JIA. Aim: To evaluate bone mass and quality determinants, and to identify the main predictors of reduced Bone Mineral Density (BMD) and bone quality using these techniques in JIA. Methods: One hundred and fifty-one patients (median 15.6, range 9.7 to 35.2 years; 101 oligoarticular, 30 polyarticular, 15 systemic, and 15 enthesitis-related-arthritis onset [ERA]) were evaluated. Of these, fifty-nine consecutive patients were followed-up with a second evaluation. The data obtained were compared with 80 ages- and sex- matched healthy subjects. Results: At the first evaluation, JIA patients showed a reduced spine aBMD SDS value in comparison to controls (p < 0.005). JIA patients showed also significant musculoskeletal deficits, with lower levels of TrabBMD (p < 0.0001), muscle CSA (p < 0.005), SSIp (p < 0.05), and significantly increased levels of fat CSA than controls (p < 0.0001). Finally, JIA patients presented a significantly reduced AD-SoS (p < 0.001), and QUS z-score (p < 0.005). These data were confirmed also in longitudinal evaluation. However, evaluating different treatments, we showed a significant negative correlation among aBMD value (p < 0.005), TrabBMD (p < 0.005), AD-SoS (p < 0.005), and systemic corticosteroids exposure or intra-articular corticosteroids injections, and a positive correlation among TNF-alpha-blocking agents and aBMD (p < 0.005), TrabBMD (p < 0.005), and AD-SoS (p < 0.005). Conclusions: Pts with JIA have a low bone mass and quality in comparison to controls, and do not reach the normal condition over time despite the current more effective drugs.