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Reactive Arthritis A006

Last amended 
29 October 2018

Current RMA Instruments

Reasonable Hypothesis SOP

75 of 2018

Balance of Probabilities SOP

76 of 2018

Changes from previous Instruments

SOP Bulletin 204

ICD Coding

  • ICD-9-CM Codes: 099.3, 711.10-711.19, 372.33
  • ICD-10-AM Codes: M02

Brief description

Reactive arthritis is an immune reaction that typically presents as an acute onset arthritis that develops between several days and around 4 weeks after an infection elsewhere in the body.  The arthritis usually asymmetrically involves one or a few joints, most commonly in the lower limbs.  The preceding infection typically affects the digestive tract (dysentery) or the urogenital tract (urethritis).  There may be other musculoskeletal symptoms and extra-articular manifestations, involving the eyes, mucosa and skin.

Confirming the diagnosis

The diagnosis is made based on the clinical findings and by the exclusion of other diseases and can be made by a GP.  A range of investigations may be needed, including examination/testing of joint fluid, blood testing and testing for urinary or gastrointestinal infection.

The relevant medical specialist is a rheumatologist.

Additional diagnoses covered by SOP

  • Reiter’s syndrome

Conditions not covered by SOP

  • Lyme disease*
  • Leptospirosis*
  • Septic arthritis#
  • Post-streptococcal reactive arthritis#
  • Rheumatic fever#
  • Arthritis due to Ross river virus*
  • Arthritis due to Barmah forest virus#
  • Arthritis due to Rubella virus#
  • Arthritis due to parvovirus#

* another SOP applies

#   non-SOP condition

Clinical onset

Reactive arthritis is a relatively rare condition that mostly affects young adults.  The usual clinical onset is an acute asymmetric oligoarthritis that almost always develops between a few days and four weeks after the inciting infection.

Clinical worsening

The typical disease duration is 3 to 5 months.  A small proportion of patients may experience more chronic persisting arthritis. The only SOP worsening factor is for inability to obtain appropriate clinical management.