117 - Classification and epidemiology of spondyloarthritis

Abstract

Spondyloarthritis (SpA) describes a spectrum of specific conditions with clinical manifestations affecting the axial skeleton, in particular the sacroiliac joints and the spine, entheses, and peripheral joints. Acute anterior uveitis is a typical extraarticular manifestation of SpA, whereas psoriasis and inflammatory bowel disease are associated conditions, both of which occur more often in SpA than expected, most likely because of overlapping pathophysiology. As a group of disorders, spondyloarthritis has a prevalence of 0.3% to 1.9% worldwide. The concept of interrelated yet distinct subgroups, including ankylosing spondylitis (radiographic axial SpA, r-axSpA), reactive arthritis, arthritis associated with psoriasis or with inflammatory bowel syndrome, and undifferentiated SpA, has evolved to a concept of predominant axial SpA or predominant peripheral SpA. The change in concept was driven primarily by an unmet need for an earlier diagnosis of ankylosing spondylitis, the most prevalent subtype of SpA. Magnetic resonance imaging (MRI) and HLA-B27 play an important role in both diagnosing and classifying axial SpA. The Assessment of SpondyloArthritis international Society classification criteria for axial SpA were established in 2009 and facilitated the conduct of clinical trials in axial SpA, which led to approval of new drugs across the spectrum of axial SpA.