Axial spondyloarthritis (axSpA) is a spectrum of painful inflammatory axial disease.
axSpA can be considered as a spectrum of disease consisting of non-radiographic axial spondyloarthritis (nr-axSpA) and ankylosing spondylitis (AS).1
At least 50% of patients are likely to progress from nr-axSpA to AS in their lifetime.2
Risk factors for progression include:2

HLA-B27 positive

High inflammatory activity
• Elevated CRP
• Inflammatory changes in sacroiliac joints on MRI

Buttock pain

Smoking

Previous uveitis

Low-grade sacroiliitis
AS, ankylosing spondylitis; axSpA, axial spondyloarthritis; CRP, C-reactive protein; HLA-B27, human leukocyte antigen B27; MRI, magnetic resonance imaging; nr-axSpA; non-radiographic axial spondyloarthritis.
References:
- Rudwaleit M, et al. Ann Rheum Dis. 2009;68(6):777–783.
- Protopopov M & Poddubnyy D. Expert Rev Clin Immunol. 2018;14(6):525–533.