Radiographic versus non-radiographic axial spondyloarthritis

Radiographic versus non-radiographic axial spondyloarthritis (1,2):

• previously, the diagnosis of ankylosing spondylitis required advanced changes on plain radiographs of the sacroiliac joints
• classification criteria released in 2009, however, identified a subset of patients, under the age of 45, with back pain for more than three months in the absence of radiographic sacroiliitis who were classified as axSpA based on a positive magnetic resonance imaging or HLAB27 positivity and specific clinical features. This subgroup was labeled non-radiographic axial spondyloarthritis
  • many patients without radiographic findings manifest MRI findings of bone marrow edema (BME) adjacent to the sacroiliac joints, suggestive of osteitis
  • one review suggests progression from non-radiographic to radiographic SpA is 10-20% over the first year, depending on baseline features such as elevated C reactive protein or positive MRI and 20.3% over two to six years (1)
  • another review states high inflammatory activity (inflammation of MRI of thesacroiliac joints, elevated CRP), HLA-B27 positivity, presence of low-grade structural damage and smoking are factors associated with progression from non-radiographic to radiographic stage (2)

Reference:

• (1) Ritchlin C, E Adamopoulos IE. Axial spondyloarthritis: new advances in diagnosis and management. BMJ 2021;372:m4447
• (2) Protopopov M, Poddubnyy D. Radiographic progression in non-radiographic axial spondyloarthritis Expert Review of Clinical Immunology 2018, VOL. 14, NO. 6, 525–533https://doi.org/10.1080/1744666X.2018.1477591.