Axial spondyloarthritis

The term axial spondyloarthritis covers both patients with non-radiographic and radiographic axial spondyloarthritis, which is also termed ankylosing spondylitis. The disease usually starts in the third decade of life with a male to female ratio of two to one for radiographic axial spondyloarthritis and of one to one for non-radiographic axial spondyloarthritis. More than 90% heritabilty has been estimated, the highest genetic association being with HLA-B27. The pathogenic role of HLA-B27 is still not clear although various hypotheses are available. On the basis of evidence from trials the cytokines tumour necrosis factor (TNF)-α and interleukin-17 appear to have a relevant role in pathogenesis. The mechanisms of interaction between inflammation and new bone formation is still not completely understood but clarification will be important for the prevention of long-term structural damage of the bone. The development of new criteria for classification and for screening of patients with axial spondyloarthritis have been crucial for the early indentification and treatment of such patients, with MRI being the most important existing imaging method. Non-steroidal anti-inflammatory drugs and TNF blockers are effective therapies. Blockade of interleukin-17 is a new and relevant treatment option.