polyarticular onset juvenile idiopathic arthritis

Last reviewed 01/2018

Polyarticular JIA (poly-JIA) is defined as arthritis of five joints or more during the first 6 months of the disease.

  • is the second most common JIA  and accounts for 25% to 40% cases.
  • prevalence is estimated to be
    • 40 per 100,000 children for RF-negative subtype
    • 10 per 100,000 children for RF-positive subtype
  • more common among girls (1,2)

The condition is further divided into

  • rheumatoid factor (RF) positive -
    • approximate frequency is between 2-10 %
    • more common in later childhood and adolescence 
    • resembles the adult RF-positive rheumatoid arthritis
      • many paediatric rheumatologists consider this JIA subtype to be earlier-onset RA
  • RF negative
    • approximate frequency is between 11-30 %
    • displays a biphasic trend with peaks of onset between 2 and 4 years and 6 and 12 years
    • several subgroups have been identified e.g. -  resembling early-onset oligoarticular juvenile idiopathic arthritis, resembling adult-onset RF-negative rheumatoid arthritis etc (1,2,3)

The disease is characterised by the insidious (sometimes acute), onset of symmetric arthritis in five or more joints

  • involve
    • both large and small joints
    • cervical spine - frequently
    • temparomandibular joints
  • mild systemic features e.g. - low-grade fever, lymphadenopathy, and hepatosplenomegaly
  • uveitis - an increased incidence is seen in RF-negative subgroup
  • RF positive subtype patients are more likely to have  symmetric small-joint arthritis, rheumatoid nodules, and early erosive synovitis with a chronic course (1,2,3)

Reference:

Related pages:

clinical features

investigations

complications

management

prognosis