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Ankylosing Spondylitis N005

Last amended 
26 June 2015
Current RMA Instruments:
Reasonable Hypothesis SOP
3 of 2013
Balance of Probabilities SOP
4 of 2013
Changes from Previous Instruments:

SOP Bulletin 163

 ICD Coding:
  • ICD-9-CM Codes: 720.0
  • ICD-10-AM Codes: M45

This is a chronic progressive systemic inflammatory condition which mainly affects the spine (spondylitis), the costovertebral joints and sacroiliac joints leading to a fusion of the affected vertebrae (ankylosis). Since it affects the spine it is also called a spondyloarthropathy. See note below about other manifestations.

Is specific diagnostic evidence required to apply the SOP?No.

The diagnosis is based on X-ray evidence as well as blood tests (ESR [Erythrocyte Sedimentation Rate], HLA B27). The appropriate medical specialist for this condition is a rheumatologist.

Are there sub-factors that require specific information? – No.
Additional diagnoses covered by SOP
  • Marie-Strumpell disease
  • Von Bechterew’s disease
Additional diagnoses which may be covered (further information required)
  • HLA B27 spondyloarthropathy
  • Inflammatory sacroilitis
  • Sero-negative spondyloarthropathy
Conditions excluded from SOP
  • Osteoarthritis or spondylosis of spine, ICD code 721.3
  • Spondyloarthropathy – due to reactive arthritis (code 711.1); due to psoriatic arthritis (code 696.0); due to inflammatory bowel disease (code 555)
  • Psoriatic spondylitis, ICD code 696.0
  • Rheumatoid arthritis of the spine, code to 714.0
Unconfirmed diagnosis

If, after considering the above information you are unable to apply the SOP, you should then:

  1. seek medical officer advice about further investigation, or;
  2. generate a diagnostic report, or;
  3. re-encode the condition, if appropriate.

The following investigations may be useful in establishing the diagnosis.

  • report from treating specialist
  • plain X-rays showing typical features can be diagnostic

Note: Other manifestations of ankylosing spondylitis

This systemic disease also may have other manifestations affecting:

  • Other joints – peripheral asymmetric arthritis with synovitis.
  • Enthesitis – inflammation of some tendon bone insertions.
  • Eye changes – anterior uveitis
  • Cardiac problems – aortic regurgitation; conduction abnormalities.
  • Pulmonary changes – apical pulmonary fibrosis

There are also other complications arising from the spinal pathology such as spinal stenosis with radiculopathy and myelopathy; osteoporosis and spinal compression fractures.