Juvenile Idiopathic Arthritis (JIA)

Hala Etayari
JIA - Background
Juvenile idiopathic arthritis (JIA) is a group of heterogeneous diseases sharing the presence of chronic arthritis (arthritis for more than 6 weeks) developing before the 16th birthday, of unknown cause, after the exclusion of other causes of chronic arthritis.
Collectively, this group constitute the most common rheumatic condition in children.
The term JIA has replaced previous nomenclature including "Juvenile rheumatoid arthritis" used in U.S.A and "Juvenile chronic arthritis" used in Europe.
The original classification of JIA has been revised several times. The International League of Associations for Rheumatology (ILAR) developed the most recent classification system which describes seven categories of JIA (Table 1) in 2001, resulting in further clarification of the various subsets, correction of prior incongruence, and improvement in clinical utility to the rheumatologist. Also it provides an important framework for research in JIA as well as assisting with appropriate treatment and prediction of natural history.(1)

The principle of this classification is that all categories of JIA are mutually exclusive. This principle is reflected in the list of possible exclusions for each category:
a) A psoriasis or a history of psoriasis in the patient or first degree relative.
b) Arthritis in HLAB27 positive male beginning after the 6th birthday.
c) Ankylosing spondylitis, enthesitis related arthritis, sacroiliitis with inflammatory bowel disease, Reiter's syndrome, or acute anterior uveitis or history of one of these disorders in a first-degree relative.
d) The presence of IgM rheumatoid factor on at least 2 occasions at least 3 months apart.
e) The presence of systemic JIA manifestations

Table 1: ILAR classification of JIA
Category Diagnostic criteria
Systemic arthritis (sJIA) Fever of at least 2 weeks duration (daily for at least 3 days) and arthritis in one or
more joints, plus one of the following:
• erythematous rash
• generalised lymph node enlargement
• hepatomegaly and/or splenomegaly
• serositis
Exclusions: a, b, c, d.
Oligoarthritis Arthritis affecting = four joints during the first 6 months of the disease. If after 6 months more than four joints are involved the term extended oligoarthritis is used
Exclusions: a, b, c, d, e.
Polyarthritis (rheumatoid factor negative)(seronegative) Arthritis affecting = five joints during the first 6 months of the disease with
rheumatoid factor negative
Exclusions: a, b, c, d, e.
Polyarthritis (rheumatoid factor positive)(seropositive) Arthritis affecting = five joints during the first 6 months of disease with
rheumatoid factor positive on at least two occasions at least 3 months apart
Exclusions: a, b, c, e.
Psoriatic arthritis (psJIA) Arthritis and psoriasis or arthritis and at least two of the following:
• dactylitis
• nail pitting or onycholysis
• psoriasis in a first degree relative
Exclusions: b, c, d, e.
Enthesitis related arthritis (ERA) Arthritis and enthesitis or arthritis or enthesitis with at least two of the following:
• presence/history of sacroiliac joint tenderness and/or inflammatory lumborsacral
pain and HLA-B27 positive
• onset of arthritis in a male over 6 years of age
• acute (symptomatic) anterior uveitis
• history of ankylosing spondylitis, enthesitis related arthritis, sacroiliitis with
inflammatory bowel disease or acute anterior uveitis in a first degree relative
Exclusions: a, d, e.
Undifferentiated arthritis Arthritis that fulfils criteria in no category or in two or more of the above categories

Juvenile Idiopathic Arthritis (JIA) Juvenile Idiopathic Arthritis (JIA) 5/11/2016
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