Juvenile idiopathic arthritis (JIA) is arthritis of unknown etiology that
begins before the 16th birthday and persists for at least 6 weeks:
other known conditions are excluded.
Exclusions
The principal 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. Psoriasis or a history of psoriasis in the patient or first-degree
relative.
b. Arthritis is an HLA-B27 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 these disorders in the 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 in the patient
The applications of exclusions is indicated under each category,
and may change as new data becomes available.
Systemic Arthritis
Definition: Arthritis in one or more joints with or preceded
by fever of at least 2 weeks duration that is documented to be daily
(“quotidian”) for at least 3 days,
and accompanied by one or more of the following:
1. Evanescent (nonfixed) erythematous rash
2. Generalized lymph node enlargement
3. Hepatomegaly and/or splenomegaly
4. Serositis
Exclusions: a, b, c, d.
Oligoarthritis
Definition: Arthritis affecting one to 4 joints during
the first 6 months of disease.
Two subcategories are recognised:
1. Persistent oligoarthritis: Affecting not more than 4 joints throughout
the disease course
2. Extended oligoarthritis: Affecting a total of more than 4 joints
after the first 6 months of disease
Exclusions: a, b, c, d, e.
Polyarthritis (Rheumatoid Factor Negative)
Definition: Arthritis affecting 5 or more joints during
the first 6 months of disease; a test for RF is negative
Exclusions: a, b, c, d, e
Polyarthritis (Rheumatoid Factor Positive)
Definition: Arthritis affecting 5 or more joints during
the first 6 months of disease: 2 or more tests for RF at least 3
months apart during the first 6 months of disease are positive
Exclusions: a, b, c, d, e
Psoriatic Arthritis
Definition: Arthritis and psoriasis, or arthritis and at
least 2 of the following:
1. Dactylitis
2. Nail pitting or onycholysis
3. Psoriasis in a first-degree relative
Exclusions: b, c, d, e
Enthesitis Related Arthritis
Definition: Arthritis and euthesitis, or arthritis or enthesitis
with at least 2 of the following:
1. The presence of or a history of sacroiliac joint tenderness and/or
inflammatory lumbosacral pain
2. The presence of HLA-B27 antigen
3. Onset of arthritis in a male over 6 years of age
4. Acute (symptomatic) anterior uveitis
5. History of ankylosing spondylitis, enthesitis related arthritis,
scaroiliitis with inflammatory bowel disease, Reiter’s syndrome,
or acute anterior uvietis in a first-degree relative
Exclusions: a, d, e.
Undifferentiated Arthritis
Definition: Arthritis that fulfils criteria in no category
or in 2 or more of the above categories.
Definitions in Terms
Arthritis: Swelling without a joint, or limitation in the
range of joint movement with joint pain or tenderness, which persists
for at least 6 weeks, is observed by a physician, and is not due
to primarily mechanical disorders or to other identifiable causes.
Dactylitis: Swelling of one or more digits, usually in
an asymmetric distribution which extends beyond the joint margin.
Enthesitis: Tenderness at the insertion if a tendon, ligament,
joint capsule, or fascia to bone.
Inflammatory lumbosacral pain: Lumbosacral spinal pain at rest
with morning stiffness that improves on movement.
Nail pitting: A minimum of 2 pits in one or more nails at any
time.
Number of affected joints: Joints that can be individually
evaluated clinically are counted as separate joints.
Positive test for rheumatoid factor (RF): At least 2 positive
results (as routinely defined in an accredited laboratory), at least
3 months apart, during the 6 months of the disease.
Psoriasis: As diagnosed by a physician (but necessarily a dermatologist).
Quotidian fever: Fever that rises to > 39C once a day and
returns to < 37C between fever peaks.
Serositis: Pericarditis and/or pleuritis and/or peritonitis.
Sacroiliac joint arthritis: Presence of tenderness on direct
compression over the sacroiliac joints.
Spondyloarthropathy: Inflammation of entheses and joints of
the lumbosacral spine.
Uveitis: Chronic anterior uveitis as diagnosed by an ophthalmologist.
References
J Rheumatol. 2004 Feb;31(2):390-2.
International League of Associations for Rheumatology classification of juvenile idiopathic arthritis: second revision, Edmonton, 2001.
Petty RE, Southwood TR, Manners P, Baum J, Glass DN, Goldenberg J, He X, Maldonado-Cocco J, Orozco-Alcala J, Prieur AM, Suarez-Almazor ME, Woo P; International League of Associations for Rheumatology.
Division of Rheumatology, Department of Pediatrics, University of British Columbia, Vancouver, BC, Canada
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