AB0746 THE ASSOCIATION BETWEEN PRESARCOPENIA AND BONE MINERAL DENSITY IN ADULT PATIENTS WITH JUVENILE IDIOPATHIC ARTHRITIS
Authors: M. Dzhus, M. Kulyk
Journal: Annals of the Rheumatic Diseases (2021)

Background: The importance of presarcopenia (low lean mass) in clinical practice is accompanied by a high risk of adverse effects such as early disability, reduced quality of life, and increased mortality. Objectives: The aim of the study was to assess the link between bone mineral density (BMD) and the state of the muscular system in adult patients with juvenile idiopathic arthritis (JIA). Methods: The study was performed in Oleksandrivska Clinical Hospital of Kyiv, Ukraine, where adult patients were transferred from pediatric rheumatologists. Inclusion criteria: patients aged 18-44 years at the time of signing the informed consent; diagnosis of JIA in childhood, verified according to ILAR criteria, duration of JIA &gt;3 years. According to the European Working Group on Sarcopenia in the Elderly (EWGSOP) 2019, patients with a decrease in muscle mass alone were diagnosed with presarcopenia. The BMD and muscle tissue were determined in standard localizations using dual X-ray absorptiometry (DXA). Results: The study included 26 adult patients with JIA, including 10 male patients and 16 female patients. The mean age at the time of examination was 22.3 ± 8.15 years; the mean age at the onset of the disease was 9.04 ± 4.9 years. According to the ILAR classification, patients had the following variants of JIA: 3 patients with RF-negative polyarticular variant, 8 patients with persistent oligoarthritis, 4 patients with extended oligoarthritis, 6 patients with RF-positive polyarthritis variant, and 5 patients with systemic JIA. According to the EWGSOP, 2019 reduced muscle mass was calculated by skeletal muscle index (SMI); the cut-off points were considered by SMI &lt;7 kg/m2 for male, &lt;6 kg/m2 for female. Patients were divided into two groups depending on the presence or absence of presarcopenia. The first group (1-st group) included 16 patients with reduced muscle mass (SMI – 5,22± 0,72 kg/m2), and the second group (2-nd group) included 10 patients without reduced muscle mass (SMI – 8,05± 0,94 kg/m2). It was found that the height and weight of patients in the group of presarcopenia was lower than in the group without a low lean mass (height 1,6±0,07 m vs 1,7±0,09 m, t=-2,53; p=0,01; weight 55,06±8,3 kg, 70,0±10,8 kg, t=-3,9; p=0,0007, respectively). The age of patients (25,3±10,1 and 21,3±5,9 years for 1-st and 2-nd groups respectively) and the duration of the disease (17,1±9,5 and 10,3±6,1 for 1-st and 2-nd groups respectively) did not differ statistically between the groups. The age of the onset of JIA in both groups also did not differ (7,8±4,5 and 11,5±4,1 for the 1-st and 2-nd group respectively). The following data were obtained by DXA. The patients of 1-st group had statistically reduced BMD in the region of femoral neck - 0,927±0,15 g/cm2 vs 1,179±0,13 g/cm2, t=-3,18; p=0,006; total hip - 0,977±0,16 g/cm2 vs 1,184±0,05 g/cm2, t=-3,05, p=0,0080; total body - 1,080±0,1 g/cm2 vs 1,193±0,15 g/cm2, t=-2,19; p=0,03; and ultra-distal radius - 0,286±0,06 g/cm2 vs 0,482±0,11 g/cm2, t=-3,60; p=0,007. The BMD in the region of lumbar spine did not differ in two groups - 1,152±0,16 g/cm2 vs 1,137±0,17 g/cm2, t=0,21; p=0,8. In the group of presarcopenia there was a visible decrease in the level of the metabolite of vitamin 25(OH)D3, but not statistically significant: 15,5±7,3 nmol/l vs 19,7±8,6 nmol/l, t =1,0; p=0,3. The study has strengths such as first described presarcopenia in young adults with JIA and potential limitations such as mono-center study and a small number of patients. Conclusion: The BMD in the region of total hip, femoral neck, ultra-distal radius, and total body in patients with decreased muscle mass was significantly lower than in patients without low lean mass. References: [1]Cruz-Jentoft AJ, Bahat G, Bauer J, et al. Sarcopenia: revised European consensus on definition and diagnosis [published correction appears in Age Ageing. 2019 Jul 1;48(4):601]. Age Ageing. 2019;48(1):16-31 Disclosure of Interests: None declared