IBP is deleted as obligatory entry criterion and implemented as an additional SpA feature. Starting point is the presence of chronic back pain longer than three months with an onset of back pain before the age of 45.
SpA: spondyloarthritis; AS: ankylosing spondylitis; x-rays: plain radiographs of the pelvis graded according to the modified New York criteria; IBP: inflammatory back pain; IBD: inflammatory bowel disease; CRP: C-reactive protein; ESR: erythrocyte sedimentation rate; HLA: human leukocyte antigen; MRI: magnetic resonance imaging. * >3 months, onset <45.
