recognition and referral of suspected spondyloarthritis

Last edited 12/2020 and last reviewed 07/2021

Recognition and referral in non-specialist care settings:

  • Do not rule out the possibility that a person has spondyloarthritis solely on the presence or absence of any individual sign, symptom or test result

Suspecting spondyloarthritis

  • Recognise that spondyloarthritis can have diverse symptoms and be difficult to identify, which can lead to delayed or missed diagnoses
    • Signs and symptoms may be musculoskeletal (for example, inflammatory back pain, enthesitis and dactylitis) or extra-articular (for example, uveitis and psoriasis [including psoriatic nail symptoms])
    • Risk factors include recent genitourinary infection and a family history of spondyloarthritis or psoriasis
  • Be aware that axial and peripheral spondyloarthritis may be missed, even if the onset is associated with established comorbidities (for example, uveitis, psoriasis, inflammatory bowel disease [Crohn's disease or ulcerative colitis], or a gastrointestinal or genitourinary infection)
  • Be aware that axial spondyloarthritis:
    • affects a similar number of women as men
    • can occur in people who are human leukocyte antigen B27 (HLA-B27) negative
    • may be present despite no evidence of sacroiliitis on a plain film X-ray

Referral for suspected axial spondyloarthritis

  • if a person has low back pain that started before the age of 45 years and has lasted for longer than 3 months, refer the person to a rheumatologist for a spondyloarthritis assessment if 4 or more of the following additional criteria are also present:
    • low back pain that started before the age of 35 years (this further increases the likelihood that back pain is due to spondyloarthritis compared with low back pain that started between 35 and 44 years)
    • waking during the second half of the night because of symptoms
    • buttock pain
    • improvement with movement
    • improvement within 48 hours of taking non-steroidal anti-inflammatory drugs (NSAIDs)
    • a first-degree relative with spondyloarthritis
    • current or past arthritis
    • current or past enthesitis
    • current or past psoriasis.

If exactly 3 of the additional criteria are present, perform an HLA-B27 test. If the test is positive, refer the person to a rheumatologist for a spondyloarthritis assessment.

  • if the person does not meet the criteria in recommendation above but clinical suspicion of axial spondyloarthritis remains, advise the person to seek repeat assessment if new signs, symptoms or risk factors listed in recommendation above develop
    • may be especially appropriate if the person has current or past inflammatory bowel disease (Crohn's disease or ulcerative colitis), psoriasis or uveitis

Imaging for suspected axial spondyloarthritis - initial investigation using X-ray

  • offer plain film X-ray of the sacroiliac joints for people with suspected axial spondyloarthritis, unless the person is likely to have an immature skeleton
  • diagnose radiographic axial spondyloarthritis (ankylosing spondylitis) if the plain film X-ray shows sacroiliitis meeting the modified New York criteria (bilateral grade 2–4 or unilateral grade 3–4 sacroiliitis)
  • if the plain film X-ray does not show sacroiliitis meeting modified New York criteria (bilateral grade 2–4 or unilateral grade 3–4 sacroiliitis), or an X-ray is not appropriate because the person's skeleton is not fully mature, request unenhanced MRI using an inflammatory back pain protocol

Subsequent investigation using MRI

  • Radiologists receiving a request for an inflammatory back pain MRI should perform short T1 inversion recovery (STIR) and T1 weighted sequences of the whole spine (sagittal view), and sacroiliac joints (coronal oblique view)
  • Use the ASAS/Outcome Measures in Rheumatology (OMERACT) MRI criteria to interpret the MRI as follows:
    • If the MRI meets the ASAS/OMERACT MRI criteria:
      • diagnose non-radiographic axial spondyloarthritis
    • If the MRI does not meet the ASAS/OMERACT MRI criteria:
      • do not exclude the possibility of axial spondyloarthritis
      • consider specialist musculoskeletal radiology review if there is disparity between the clinical suspicion and imaging findings, particularly in people with an immature skeleton
      • offer an HLA-B27 test if it has not already been done. If positive, base the diagnosis of non-radiographic axial spondyloarthritis on clinical features, for example, using the clinical 'arm' of the ASAS axial classification criteria

If a diagnosis of axial spondyloarthritis cannot be confirmed and clinical suspicion remains high, consider a follow-up MRI.