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The concept of Spondyloarthritis

by Roberto Russo

MRI of the sacroiliac joints showing bone marrow oedema and irregularity of the joint margins, due to sacroiliitis. Image courtesy of Anatomate-‐Apps.

MRI of the sacroiliac joints showing bone marrow oedema and irregularity of the joint margins, due to sacroiliitis. Image courtesy of Anatomate-‐Apps.

A group of the world experts recently gathered together to review the concept of the family of spondolyarthritides disorders (which include Ankylosing Spondylitis (AS)), publishing their conclusions in the most recent edition of Arthritis and Rheumatism (a major journal within the Rheumatology community).

Some of the more interesting statements include:

  • Those with Non-radiographic SpA, which is considered an earlier form of AS where damage is not yet apparent on x-rays, carry a high burden of disease, with significant pain, stiffness, loss of function, and poor quality of life equal to those with AS.
  • Therefore, those with non-radiographic axSpA need treatment early.
  • The European Medicines Agency have now approved the use of TNFa blocking medications, which are very effective in treating the symptoms of AS, for non-radiographic axSpA. However, that is not yet the case in Australia or the US.
  • A reason for which these medications are not yet available in the US is that the natural history of non-radiographic axSpA is not yet understood. A proportion of these patients appear to demonstrate spontaneous remission of their disease.
  • The prognostic factors that identify those who are more likely to progress to radiographic sacroiliitis are not sufficiently characterized, albeit raised markers of inflammation and severity of MRI changes are suggestive.
  • Also, the classification criteria used to define those with axSpA are not specific enough, exposing a significant proportion of patients to unnecessary treatment.


Consequently, the concept of axSpA was reviewed. The group considered a number of propositions and came to a consensus upon a number of concepts.

  • Axial Spondyloarthritis should be considered a single disease entity with subsets, similar to the current concept of Rheumatoid arthritis
  • Signs and symptom resolution is as important as structural damage prevention in axSpA
    • Structural damage has been given undue prominence in previous concepts of the disease
  • The term non-radiographic should be abandoned as it is deemed too confusing as a diagnostic term. They suggested the simplified term axSpA.
    • The phrase non-radiographic can be later added only to describe a subset of the disease.
  • Avoid the use of classification criteria in making a diagnosis. Physicians should base the diagnosis on their clinical assessment.
    • Classification criteria should only be used in clinical trials after a diagnosis has been made.
  • The use of MRI as an objective measure in the diagnosis of axial SpA is acceptable.
    • However, MRI should only be used when the pre-test probability for the disease is reasonable and not low.
    • Since up to 12% of healthy individuals can have MRI changes suggestive of active sacroiliitis

These are exciting times for us Rheumatologists with an interest in axSpA as the language we use to describe and conceptualise this disease appears to be changing. I applaud the expert groups for having the courage to review long held traditions and adapt as required in order to ensure the best for our patients.


Stolwijk C, Essers I, van Tubergen A, et al. The Epidemiology of Extra-articular Manifestations in Ankylosing Spondyloarthritis: A population-based matched cohort study. Annals of Rheumatic Diseases, 2014: published online March 21. DOI: 10.1136/annrheumdis-2014-205253