AB0745 BONE STATUS IN CHILDREN WITH JUVENILE IDIOPATHIC ARTHRITIS (JIA) ON T2T THERAPY
Authors: N. Shevchenko, Y. Khadzhynova, L. Bohmat
Journal: Annals of the Rheumatic Diseases (2021)

Background: In recent years approaches to both the diagnosis and treatment of JIA have changed. Among it key positions for bone health are reducing the time to make a diagnosis and initiation of basic therapy, as well as reducing the timing and doses of corticosteroids. The interdependence of osteopenia in children with JIA with established impairment of vitamin D status, the prevalence of which remains very high in this cohort of patients, has also not been definitively elucidated. Objectives: To study the condition of bone tissue in children with JIA in modern disease management and to identify adverse factors for the development of osteopenia among the clinical manifestations signs. Methods: The study included 35 children with JIA aged 7 to 17 years, mostly female (77.1%), with oligo - (25.7)%, poly - (60.0%) and undifferentiated (14.3 %) arthritis, 53.4% have not yet received basic therapy. No corticosteroid therapy was available. The study of bone tissue was performed by two-energy X-ray absorptiometry (Explorer QD W-Hologic). All patients were tested for serum parathyroid hormone (PTH), the level of 25-hydroxyvitamin D [25(OH)D], the total and ionized calcium and blood phosphorus. The control group consisted of 12 healthy children of the same age with a normal level of 25 (OH) D. Results: The average level of 25(OH)D was 20.41±1.35 ng/ml, which is considered insufficient and was lower than in the control group (30.03±2.53 ng/ml, p&lt;0.05). Studies of calcium and phosphorus in the blood showed that children with JIA have no deviations from the normative values. The majority of examined patients (98.37%) had normal values of PTH, in average was 30.43±0.90 pg/ml. The PTH was significantly different in children with different variants of JIA, the highest content was recorded in non-differential arthritis (34.33±1.80 pg/ml), the lowest - in the oligoarticular variant (28.36±1.43, p&lt;0,05). PTH had a negative correlation with 25(OH)D status (r = -0.41; p &lt;0.05) and did not depend on the sex and disease activity. The incidence of osteopenia was 28.57%, its prevalence was almost the same in different variants of arthritis and did not depend on the sex and age of patients, positivity for RF. Osteopenia was more common in ANA-positive than in ANA-negative variant (46.15% vs. 18.18%; p φ &lt;0.05). In 30.0% patients with osteopenia decreased BMD reached the values of osteoporosis (more than 2.5σ). This group consisted of girls with predominantly polyarticular and undifferentiated JIA, with RF-negative and ANA-positive variant. Deviations from the age normative values of BMD (Z-score) were associated with BMI (r=0.33; p &lt;0.05), JADAS scale results (r=0.35; p&lt;0.04), the number of active joints (r=0.34; p&lt;0.05), ANA (r=-0.34; p&lt;0.05). In children with osteopenia it was correlated with the duration of the disease (r=-0.67; p&lt;0.05), the number of active joints (r=-0.62; p&lt;0.05), blood phosphorus level (r=0.74; p&lt;0.05) and JADAS scale results (r=0.59; p&lt;0.05). In children with preserved BMD correlations was supplemented by 25(OH)D status (r=-0.33; p&lt;0.05) and BMI (r=-0.40; p&lt;0.05). Analysis of the interdependence of the formation of osteopenia and clinical manifestations signs established the total significance of the main parameters of the disease with the highest coefficient of determination in the polyarticular variant: -112.65 + 0.09(patient’s age, mo)+4.33 (patient’s sex)-3.74 (ANA, units)-1.80 (RF, units)+0.01 (age of onset, months)-0.34 (number of affected joints)-0.18 (number of active joints)-0.18 (ESR, mm/h)+71.58 (ionized calcium, mmol/l)+5.19 (phosphorus, mmol/l)-0.01 (PTH, ng/ml)+0.18 (25(OH)D, ng/ml)(R 2 =99.99%; p&lt;0.001). Conclusion: With modern JIA management a quarter of children have osteopenia. The state of the bone tissue is more associated with the prevalence, immunological and inflammatory activity of the disease against the background of preserved calcium-phosphorus homeostasis and vitamin D deficiency, and is not associated with the present therapy. Disclosure of Interests: None declared