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 >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 <7 kg/m2 for male, <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):16-31Disclosure of Interests:None declared
Bivariate Whole Genome Linkage Analyses for Total Body Lean Mass and BMD