Longitudinal assessment of disease activity and muscle strength in juvenile dermatomyositis: a multicentre registry study

To define disease activity measures, muscle strength and functional assessments in new-onset juvenile dermatomyositis (JDM) patients, at disease onset and follow up. A registry was set up in 18 hospitals, enrolling patients over 3-years (2015-2018). Clinical assessments were performed at baseline, and at 6, 12, 18 and 24 months after diagnosis. Disease Activity Score (DAS20), skin and musculoskeletal DAS sub-scales; Manual Muscle Test (MMT8); Childhood Myositis Assessment Scale (CMAS); Childhood Health Assessment Questionnaire disability index (CHAQ_DI 0-3) and 10 cm Visual Analog Scale (VAS) for overall wellbeing scores were compared by Poisson Model and Wald post-test for repeated measures. Ninety-six cases, being 61 (64%) females, median age 10 years had JDM diagnosis and 12 (13%) onset calcinosis. Mean ±SD scores at diagnosis and 6 months intervals for DAS20 (0-20) were 7.8±5, 6.3 ±4.8, 5±4, 4.9 ±5 and 0.5 ±2.3; with significant difference from baseline (p