POS0907 Association between disease activity and damage in idiopathic inflammatory myopathies. Differences between incident and prevalent cases

Background There are different measures and tools validated to evaluate disease activity and damage in idiopathic inflammatory myopathies (IIM). Disease activity and damage in patients with early diagnosis is not still well defined. Objectives To analyze disease activity outcomes and their association with damage in IIM differentiating between incident and prevalent cases. Methods Multicenter cross-sectional study of a cohort of patients included in the Spanish Registry of patients with IIM (Myo-Spain)(1). Patients were classified as incident cohort (time between diagnosis and study initiation ≤ 12 months) or prevalent cohort (> 12 months). Activity and damage data were collected at the initial visit. Differences between both groups were tested by Chi-square, Student’s t and Mann-Whitney tests. Spearman’s correlation coefficients (Rho) were used to analyze correlations between disease activity and damage measures (weak ≥ 0.2 - <0.3; moderate ≥ 0.3