Introduction to axial spondyloarthritis

Axial spondyloarthritis is an inflammatory arthropathy that affects the spine. The term axial spondyloarthritis incorporates nonradiographic axial spondyloarthritis (an earlier stage of disease before definite spinal changes can be identified on plain X-ray) and ankylosing spondylitis. Ankylosing spondylitis affects up to 0.5% of the population and occurs predominantly in men.

The human leucocyte antigen B27 (HLA-B27) is found in more than 90% of patients with ankylosing spondylitis, but is not a useful diagnostic indicator in isolation because it is also present in about 10% of the normal Australian population. The presence of HLA-B27 in an individual confers a risk of approximately 8% of developing ankylosing spondylitis; this risk is increased to 20% if a first-degree relative has ankylosing spondylitis.

Axial spondyloarthritis often follows a chronic relapsing and remitting course. Disease severity varies considerably between patients.

For general information on the spectrum of spondyloarthritis diseases, see Overview of spondyloarthritis.