Four phenotypes of chronic back pain suspicious of axial spondyloarthritis (axSpA) in the SPACE cohort. These groups were: They were “axial”, “axSpA with peripheral signs”, “at risk” and “no SpA”. Over a 2 year follow up, Transitions between the four classes over two years were… https://t.co/lF1wtAo46Q https://t.co/BXj1nw0tto