Juvenile idiopathic arthritis

Table 1 Classification of subtypes of juvenile idiopathic arthritis[12]

Systemic arthritis

Definition: Arthritis in one or more joints with or preceded by fever of at least 2 wk’ duration that is documented to be daily (“quotidian”) for at least 3 d, and accompanied by one or more of the following:

1 Evanescent (non-fixed) erythematous rash

2 Generalized lymph node enlargement

3 Hepatomegaly and/or splenomegaly

4 Serositis

Exclusions: 1 to 4

Oligoarthritis

Definition: Arthritis affecting one to 4 joints during the first 6 mo of disease. Two subcategories are recognized:

1 Persistent oligoarthritis: Affecting not more than 4 joints throughout disease course

2 Extended oligoarthritis: Affecting a total of more than 4 joints after the 6 mo of oligoarticular disease

Exclusions: 1 to 5

Polyarthritis (Rheumatoid factor negative)

Definition: Arthritis affecting 5 or more joints during the first 6 mo of disease; a test fot RF is negative.

Exclusions: 1 to 5

Polyarthritis (Rheumatoid factor positive)

Definition: Arthritis affecting 5 or more joints during the first 6 mo of disease; 2 or more tests for RF at least 3 mo apart during the first 6 mo of disease are positive.

Exclusions: 1, 2, 3, 5

Psoriatic arthritis

Definition: Arthritis and psoriasis, or arthritis and at least two of the following:

1 Dactylitis

2 Nail pitting or onycholysis

3 Psoriasis in a first-degree relative

Exclusions: 2, 3, 4, 5

Enthesitis related arthritis

Definition: Arthritis and enthesitis, or arthritis or enthesitis with at least two of the following:

1 The presence or a history of sacroiliac joint tenderness and/or inflammatory lumbosacral pain

2 HLA-B27 positivity

3 Onset of arthritis in a male over 6 yr of age

4 Acute (symptomatic) anterior uveitis

5 History of ankylosing spondylitis, enthesitis-related arthritis, sacroiliitis with inflammatory bowel disease, reactive arthritis, or acute anterior uveitis in a first-degree relative

Exclusions 1, 4, 5

Undifferentiated arthritis

Definition: Arthritis that fulfills criteria in no category or in 2 or more of the above categories

Exclusion criteria for JIA

1 Psoriasis or a history of psoriasis in a first-degree relative

2 Arthritis in an HLA-B27 positive male following his 6th birthday

3 History of ankylosing spondylitis, enthesitis-related arthritis, sacroiliitis with inflammatory bowel disease, reactive arthritis (Reiter’s syndrome), or acute anterior uveitis in a first-degree relative

4 The presence of IgM rheumatoid factor on 2 or more occasions at least 3 mo apart

5 The presence of systemic JIA in the patient

JIA: Juvenile idiopathic arthritis; HLA: Human leukocyte antigen.