Performance characteristics of the simplified version of ankylosing spondylitis disease activity score (SASDAS)

Various types of disease activity measures are available for axial spondyloarthritis (axSpA), and there is no gold standard for all individual patients. The ankylosing spondylitis disease activity score (ASDAS) is highly discriminatory, sensitive to change, and associated with structural progression. A simplified version of the ASDAS (SASDAS) was proposed and found to be a simple and practical tool to assess disease activity. Our aim was to test the performance characteristics of the SASDAS and compare it with validated tools. In total, 97 consecutive ankylosing spondylitis (AS) patients were included in the study. Disease activity was assessed by the ASDAS-erythrocyte sedimentation rate (ESR), ASDAS-C-reactive protein (CRP), bath ankylosing spondylitis disease activity index (BASDAI), and SASDAS. The relationship among these activity indices and the level of agreement of various activity categories were tested. There was a strong correlation between the SASDAS and other activity indices, including the BASDAI ( r = 0.916, p