Non-radiographic axial spondyloarthritis: what is it?

The classification criteria recently developed by the Assessment of Spondyloarthritis International Society (ASAS) highlighted a specific entity: non radiographic axial spondyloarthritis (nr-axSpA). Although more and more widely used in the literature as well as clinical trials, limits and profile of this entity is still under known or debated. Some studies have already compared those forms to classical AS, even in recent forms. They showed that, apart from the difference in the ossification process, and the greater degree and frequency of systemic and MRI inflammation in AS, those 2 forms of SpA share the same genetic background, clinical patterns, and burden of disease. TNF antagonists seemed as effective in controlling symptoms in patients with nr-axSpA. Concerning the long-term outcome of nr-ax-SpA, only long-term ongoing cohorts of patients with recent nr-axSpA will be able to determine what proportion of patients have persistent non-radiographic disease and what proportion do progress to AS.