11/14/24, 10\:59 AM Juvenile Idiopathic Arthritis

Juvenile Idiopathic Arthritis

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Juvenile idiopathic arthritis (JIA)\: paediatric in
Prevalence\: 1 in 1,000 children under 16; twice as common in females.
Subtypes (ILAR)\: oligoarthritis, RF-positive polyarthritis, RF-negative polyarthritis, systemic-onset arthritis, psoriatic arthritis,
enthesitis-related arthritis, undi
Aetiology\: unknown; involves genetic susceptibility and environmental triggers. Associated with HLA polymorphisms.
Risk factors\: female sex, family history of autoimmune diseases, Down's syndrome.
Symptoms\: joint pain >6 weeks, joint swelling, high-grade fever, early morning sti
changes, connective tissue symptoms.
Subtypes features\:
Oligoarthritis\: 1-4 large joints.
RF-negative polyarthritis\: ≥5 large/small joints, symmetrical.
RF-positive polyarthritis\: ≥5 large/small joints, rapid progression.
Systemic-onset arthritis\: ≥1 joint, fever, salmon-coloured rash, organomegaly.
Psoriatic arthritis\: arthritis + psoriasis/nail changes.
Enthesis-related arthritis\: weight-bearing joints, sacroiliitis.
Examination
(rash, uveitis, dactylitis, nail changes).
Investigations\:
FBC\: exclude infection/malignancy.
In
RF, anti-CCP\: positive in RF-positive polyarticular JIA.
ANA, HLA-B27\: assess uveitis risk, enthesis-related JIA.
X-ray\: rule out other pathologies, baseline.
Ultrasound, MRI\: assess synovitis, bone erosions.
Ophthalmologic exams\: uveitis screening.
Management goals\: control in
toxicity.
Multidisciplinary input\: OT, PT, paediatric orthopaedics, ophthalmology, rheumatology.
Conservative management\: moderate-intensity exercises (aerobic,
Medical management\:
NSAIDs\: initial symptomatic treatment.
Intra-articular glucocorticoid injections\: active arthritis with few joints.
DMARDs\: methotrexate (1st line), le
Corticosteroids\: short-term for severe arthritis/systemic symptoms.
Biologic agents\: TNF-alpha inhibitors, IL-6 inhibitors, selective B-cell blockade, JAK inhibitors.
Pre-biologic/DMARD screening\: TB, varicella status, baseline blood tests.
Complications\: joint contractures, leg length discrepancies, uveitis, growth retardation, osteoporosis, joint erosion.
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Macrophage activation syndrome (MAS)\: life-threatening complication of systemic JIA, presents with high fever, rash,
hepatosplenomegaly, bruising, mucosal bleeding.
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A comprehensive topic overview

Introduction

Juvenile idiopathic arthritis (JIA) is a term used to describe a group of paediatric in
longer than six weeks and emerge before the age of 16 years. 1,2 4
JIA is a clinical diagnosis.
JIA is the most common chronic in
10,000 children are diagnosed annually, giving a prevalence of 1 in 1,000 children under 16 years of age. 5
JIA is twice as
common in females than in males.
5,6
There are seven diInternational League of Associations for
Rheumatology (ILAR)\:
2,3
1. Oligoarthritis
2. Rheumatoid factor-positive polyarthritis
3. Rheumatoid factor-negative polyarthritis
4. Systemic-onset arthritis (Still’s disease)
5. Psoriatic arthritis
6. Enthesis-related arthritis
7. Undi

Aetiology

The exact aetiology of JIA is unknown however it is thought to occur in genetically susceptible individuals following a
trigger by various environmental factors. Several di
HLA A2, HLA B27) have been associated with the various JIA subtypes.
1.7

Pathophysiology

JIA results from an immune-mediated in
the subtype, there may also be skin and eye involvement.
8

Risk factors

Although the exact aetiology remains unknown, the following risk factors are associated with an increased likelihood of
developing JIA\:
9,21
Female sex
First-degree relative with juvenile idiopathic arthritis
Family history of any autoimmune disease
Down's syndrome (trisomy 21)

Clinical features

History

Typical symptoms of JIA include\:
1
Joint pain lasting more than 6 weeks
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Joint swelling
Fever\: high grade fever (>5°C), spiking once to twice daily for ≥2 days/week for ≥2 weeks
Other symptoms may include\:
1,10
Early morning sti
lower limb joints are involved
Mobility\: reduced mobility may be due to pain (in active disease) or secondary to joint contractures (in long-standing
disease)
Uveitis\: periocular pain, photophobia, blurry vision, increased lacrimation
Nail changes\: pitting, onycholysis
Connective tissue symptoms\: hair loss, mouth ulcers, rash and Raynaud’s phenomenon
Pain on chewing\: may indicate TMJ disease activity
Unintentional weight loss\: consider malignancy
Interference with sports/schoolwork\: ask about handwriting and physical activity (e.g. “does your arthritis ever stop you
from doing what you want to do?”)
Bowel symptoms\: ask about bowel motion frequency and whether any blood/mucus in stool as patients may have co-
existing in
The seven recognised subtypes have di
Table 1. Clinical features of di
10,11
Subtype
Pattern of joint
involvement
Other features
1-4 large joints
Oligoarthritis
Most common
(knees, ankles, elbows,
wrists)
5 or more large and small
joints
Rheumatoid
factor-negative
polyarthritis
Symmetrical involvement
(hands, feet, TMJ, cervical
spine)
Rheumatoid
factor-positive
polyarthritis
5 or more large and small
joints
Symmetrical involvement
1 or more joints
Systemic-onset
arthritis
Rapidly destructive
Most severe
Daily fever spikes, plus 1+ of\:
Erythematous “salmon-colour”
rash
Generalised
lymphadenopathy,
hepatosplenomegaly and
serositis
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Psoriatic arthritis 1 or more joints
Arthritis & psoriasis OR arthritis &
2+ of\:
Nail changes
Psoriasis in 1st-degree relative
Knees and small joints of
hands and feet a
Erythematous scaly lesions on
post-auricular area, scalp,
over extensor surfaces of
knees and elbows or peri-
umbilical area.
Enthesis-related
arthritis
Undi
arthritis
1 or more weight-bearing
joints (hip and intertarsal
joints)
Sacroiliitis
Doesn’t ful
more categories.

Clinical examination

If juvenile idiopathic arthritis is suspected, a thorough clinical examination must be performed. For more information, see
the Geeky Medics guide to the paediatric GALS examination.
Typical clinical
1,2
Swelling of a
Erythema or warmth of a
Reduced range of motion of a
and JIA.
Tenderness at entheseal insertion points (e.g sacroiliac joint)
Schober’s test\: tests the
Extra-articular manifestations
Extra-articular manifestations of JIA may be present depending on subtype\:
1,10
Psoriatic plaques\: erythematous, scaly lesions over extensor surfaces
Non-pruritic, erythematous salmon-coloured rash\: limited to the trunk and proximal extremities, worse with fever (typical
for systemic JIA)
Dactylitis
Enlarged lymph nodes
Enlarged liver or spleen on examination
Uveitis\: periocular pain, red eye, photophobia, blurry vision, increased lacrimation
Nail changes\: pitting, onycholysis
Mouth ulcers (important to check the roof of the mouth)

Di

Depending on the presenting clinical features, di
1
Malignancy
Septic arthritis
Reactive arthritis
Osteomyelitis
Acute rheumatic fever
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Systemic lupus erythematosus
Periodic fever syndrome

Investigations

Laboratory investigations

Relevant laboratory investigations include\:
1,2
Full blood count with blood
anaemia, thrombocytosis, and leukocytosis.
In
disease.
Rheumatoid factor (RF)\: positive in RF-positive polyarticular JIA and associated with aggressive disease.
Anti-cyclic citrullinated peptide antibody (anti-CCP)\: positive in RF-positive polyarticular JIA.
Anti-nuclear antibody (ANA)\: when positive, it indicates an increased susceptibility to uveitis. Positive in oligoarticular JIA
and occasionally in polyarticular JIA.
HLA-B27\: positive in enthesis-related JIA and indicates the development of symptomatic uveitis/iritis.

Imaging

Relevant imaging investigations include\:
1,2,13
X-ray of a
early stages of JIA. Nonspeci
used to rule out other pathology (e.g. fractures) and provide a baseline.
Ultrasound of a
This is abnormal in the early stages of JIA.
MRI (contrast-enhanced)\: the most sensitive imaging modality to detect synovitis, bone erosions and joint oedema.
DEXA\: important to monitor bone density in patients taking long-term oral steroids

Other investigations

Ophthalmologic investigations are performed to screen for uveitis\:
14,15
Slip lamp examination
Intraocular pressure measurement
Age-appropriate visual acuity testing
A fever diary may be useful when considering the diagnosis of systemic JIA.

Diagnosis

The diagnosis of JIA is a clinical diagnosis based on history and examination. Laboratory investigations and imaging are not
diagnostic but are important to carry out to help exclude di
evaluate for extra-articular manifestations.
12

Management

The goals of the management of JIA are to\:
Control joint in
Reduce joint damage
Promote normal growth, development, and function
Minimise toxicity from medications

Multidisciplinary input

Disciplines that are involved in the management of JIA include\:
16
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Occupational therapy\: provide a pain relief program and optimise activities of daily living
Physiotherapy\: address range of motion, muscle strengthening and conditioning
Paediatric orthopaedics\: correction of deformities, limb length discrepancies and management of advanced arthritis
Paediatric ophthalmology\: screening for and close monitoring for uveitis and associated eye complications with slip
lamp (at least annually depending on risk)
Paediatric rheumatology\: diagnosis and long-term management

Conservative management

It is important to maintain range of motion and muscle strength. Therefore moderate-intensity exercises are
recommended\:
11
Aerobic exercises (swimming)
Flexibility exercises
Strengthening exercises

Medical management

Non-steroidal anti-in
NSAIDs are used to control in
of all subtypes of JIA. 2
The use of NSAIDs is typically limited to under two weeks at a time.
Intra-articular glucocorticoid injections (IAGCI)
Intra-articular glucocorticoid injections are indicated for active arthritis involving a small number of joints. These reduce
arthralgia and are the preferred initial management.
Disease-modifying antirheumatic drugs (DMARDs)
DMARDs are used in patients with inadequate response to NSAID and IAGCIs. They are recommended in the following
order\:
18
st
Methotrexate (1 line)
Le
Sulfasalazine
Corticosteroids
Corticosteroids are used for the acute management of severe arthritis and systemic symptoms of JIA. They are also used
topically as eye drops for the management of uveitis.
Corticosteroids should be used for the shortest possible duration due to the risk of side e
17
It is important to consider calcium/vitamin D supplementation for patients on long-term oral steroids.
Biologic agents
These are monoclonal antibodies which target speci
in
Biologic agents are the last-line treatment for those with an inadequate response or intolerance to NSAIDs, IAGCI and
DMARDs.
These agents reduce systemic in
18
Tumour necrosis factor alpha (TNF-a) inhibitors\: etanercept, adalimumab, in
Interleukin 6 inhibitors\: tocilizumab
Selective B-cell blockade\: rituximab
JAK inhibitors\: the newest class of immune modulating therapy, usually prescribed when multiple biologics have failed
Pre-biologic/DMARD screening tests
Before commencing biologic agents, all patients need to be screened for
Latent tuberculosis due to the risk of reactivation\: via chest X-ray and Quantiferon blood test
Varicella status (varicella IgG) prior to commencing methotrexate
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Baseline blood tests\: neutrophil count and liver function tests (ongoing monitoring when using a
biologic/DMARD)

Complications

Complications of juvenile idiopathic arthritis include\:
1,17
Joint contractures and leg length discrepancies if ongoing in
Uveitis\: although usually asymptomatic, if left untreated, it can lead to cataracts, glaucoma, and eventual blindness
Growth retardation
Osteoporosis
Joint erosion\: may lead to a need for joint replacement in the future
Macrophage activation syndrome (MAS)
Macrophage activation syndrome (MAS) is a rare but potentially life-threatening complication of systemic-onset JIA.
MAS presents with a high fever, purpuric rash, hepatosplenomegaly, lymphadenopathy, easy bruising, and mucosal
bleeding.
21

References

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Reviewer

Dr Susan Harvey
Post-CCT Fellow and Special Lecturer in Paediatrics
Dr Sheena Coyne
Specialist Registrar in Paediatrics

Behcet’s Disease
Osteoporosis
Polymyalgia Rheumatica
Psoriatic Arthritis
Rheumatic Fever

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