Studying patients with inflammatory back pain and arthritis of the lower limbs clinically and by magnetic resonance imaging: many, but not all patients with sacroiliitis have spondyloarthropathy

Abstract

HLA B27 positivity in IBP patients with MRI-proven sacroiliitis positively predicts SpA. uSpA is a frequent SpA subset. There are HLA B27-negative non-SpA patients with moderate unilateral sacroiliitis whom we propose to be classified as US.