juvenile%20idiopathic%20arthritis
JUVENILE IDIOPATHIC ARTHRITIS
Juvenile idiopathic arthritis was formerly known as juvenile rheumatoid arthritis or juvenile chronic arthritis.
It presents as chronic joint swelling, pain with functional limitation for at least 6 weeks of unknown cause that starts before 16 year of age.
It is the most common autoimmune-autoinflammatory disease in children.
Around half of the children with juvenile idiopathic arthritis may have active disease until adulthood.

Diagnosis

  • An early & accurate diagnosis is important to start the correct management to promote normal growth & development, & to lessen disability & deformity
    • Excessive delay in diagnosis causes late treatment that leads to severe damage of joints & other organs, & impairs skeletal maturation

Classification

  • Developed by the International League of Associations for Rheumatology (ILAR) which includes all subtypes of chronic juvenile arthritis
    • Different to the classification criteria of the American College of Rheumatology (ACR) where the disease was divided according to treatment groups
  • Provides important outline for research, helps identify proper management for patients, & predicts the natural history of the disease

    Subtype Age at Onset Diagnostic Features Other Features
    Oligoarthritis
    • Persistent
    • Extended
    <6 years old
    • Affects ≤4 joints throughout course of disease
    • Affects >4 joints after the 1st 6 months of disease
    • 30% presents w/ uveitis
    • Lab test: 60% w/ positive antinuclear antibody (ANA); some w/ mild elevation in erythrocyte sedimentation rate (ESR)/C-reactive protein (CRP); other test may be normal
    Polyarthritis
    • Rheumatoid factor (RF)-negative
    • Rheumatoid factor (RF)-positive
    6-7 years old
    9-12 years old
    • Affects ≥5 joints in the 1st 6 months of disease w/ negative RF
    • Affects ≥5 joints in the 1st 6 months of disease w/ ≥2 positive RF tested at least 3 months apart
    • 10% RF-negative patients present w/ uveitis; 10% RF-positive patients have rheumatoid nodules
    • Lab test: mild-moderate elevation in ESR; normal-mild increase in CRP; mild anemia; 40% RF-negative patients w/ positive ANA
    Systemic-onset 2-4 years old
    • Affects ≥1 joints w/ or preceded by fever w/ quotidian pattern of at least 2 weeks duration, plus ≥1 of the following:
      • Transient erythematous rash
      • Enlargement of lymph nodes
      • Hepatomegaly
      • Splenomegaly
      • Pericarditis ± pleuritis ± peritonitis
    • Lab test: anemia; increase in white blood cells (WBC), platelets, ESR, CRP, ferritin
    Enthesitis-related arthritis 9-12 years old
    • Arthritis ± enthesitis plus ≥2 of the following:
      • Presence or history of sacroiliac joint tenderness &/or inflammatory lumbosacral pain
      • Positive human leukocyte (HLA) B27 antigen
      • Onset of arthritis in male >6 years old
      • Acute anterior uveitis
      • History of ankylosing spondylitis, enthesitis - related arthritis, sacroilitis w/ inflammatory bowel disease, Reiter syndrome, or family history of acute anterior uveitis
    • May have acute anterior uveitis, some w/ associated reactive arthritis or inflammatory bowel disease
    • Lab test: 80% w/ positive HLA-B27
    Psoriatic arthritis 7-10 years old
    • Arthritis ± psoriasis plus ≥2 of the following:
      • Dactylitis
      • Nail pitting & oncholysis
      • Family history of psoriasis
    • 10% presents w/ uveitis; 50% w/ psoriasis
    • Lab test: 50% w/ positive ANA; mild elevation in ESR/CRP; mild anemia
    Undifferentiated arthritis  
    • Arthritis that does not fit into any or in ≥2 of the above categories
     

Modified from: Wu EY, Van Mater HA, Rabinovich CE. Juvenile idiopathic arthritis. In: Kliegman RM, Stanton BF, St. Geme III JW, et al. Nelson textbook of pediatrics. 19th ed. Philadelphia, PA: Elsevier Saunders; 2011.

Physical Examination

  • Mainly the basis of juvenile idiopathic arthritis (JIA) diagnosis
  • JIA is highly considered in patients w/:
    • Pain & swelling of ≥1 joints; some children may not complain of pain but is usually elicited by active or passive motion
      • Constant or progressive loss of function
      • At least 10 days duration of fever that has no known cause & is often associated w/ transient erythematous rash
      • High spiking fever (≥39°C) w/ a quotidian pattern is the most recognized feature of systemic involvement
      • Lesions are most commonly seen in the trunk & proximal extremities & usually consists of discrete, circumscribed, salmon-pink 2-10 mm sized macules that may be surrounded by a ring of pallor or may develop central clearing & is usually evanescent w/ fever spikes; may be elicited by rubbing &/or scratching the skin (Koebner response), by hot bath, or by psychological stress
      • Reduced range of motion
      • Warm joints
      • Effusion
    • Patient may have complaints of morning stiffness & gelling after inactivity or swelling of affected joint after trauma
    • Any joint may be involved but large joints are more commonly affected than the smaller joints
      • Arthritis in large joints causes initial linear growth acceleration that leads to longer affected limb; constant inflammation stimulates rapid & premature closure of the growth plate that results in shortened bones
      • Cricoarytenoid arthritis is uncommon but may cause acute airway obstruction
      • Anterior atlantoaxial subluxation & impaction in the upper cervical spine is often observed rendering the affected child at risk of injury due to accident or intubation
    • Patients may also present w/ scoliosis, small outpouchings of synovium at the extensor hood of the proximal interphalangeal joint around the wrist or ankle, or synovial cyst in the antecubital fossa or anterior to the shoulder
  • Extra-articular manifestations include ocular, cardiac, pulmonary & hematopoietic involvement
    • Uveitis is the most common JIA extra-articular manifestation which involves the anterior chamber, affecting 9% of all JIA patients (eg 15-20% of patients w/ oligoarthritis, 5-10% of those w/ polyarthritis, & rarely in patients w/ systemic-onset JIA)
    • 90% occur w/in 4 years of JIA diagnosis & is usually asymptomatic at onset but may eventually cause posterior synechiae, cataract, band keratopathy, glaucoma, or macular edema
    • Growth failure is more commonly seen in patients w/ systemic arthritis due to its high inflammatory nature & repeated use of long-term oral glucocorticoid agents

Laboratory Tests

  • Helpful in increasing accuracy of the diagnosis, classifying the disease, ruling out other types of arthritis, predicting the progression of patient’s condition to an erosive type, & monitoring progression of the disease
    • Only supportive in diagnosing juvenile idiopathic arthritis (JIA) since results may be normal
  • Advised in patients who present w/ symptoms of >4 weeks duration

Erythrocyte Sedimentation Rate (ESR) & C-reactive Protein (CRP)

  • Inflammatory markers but have low specificity for JIA
    • ESR may be helpful in measuring active disease at onset & during follow up visits, esp in patients w/ polyarticular or systemic-onset JIA
    • May be used to monitor disease activity & treatment response

Rheumatoid Factor (RF)

  • Inconclusive test since present in only small percentage of patients w/ JIA
  • Recommended in patients w/ polyarthritis
  • Positive result may indicate possibility of an aggressive disease & poorer prognosis

Complete Blood Count (CBC)

  • May help identify presence of inflammation or anemia
    • Microcytic anemia may be present & attributable to chronic disease
    • Leukocytosis may be seen in children w/ active disease & platelet count elevated in severe systemic or polyarticular involvement

Antinuclear Antigen (ANA)

  • Should be assessed in all JIA patients
    • Identifies the risk for the development of asymptomatic uveitis, esp in patients w/ oligoarticular-onset disease
    • Present in 40-50% of patients w/ polyarthritis, 70-85% of patients w/ oligoarthritis, 10% of patients w/ systemic JIA & negative in patients w/ enthesitis-related JIA

Human Leukocyte Antigen (HLA)-B27

  • May be used in diagnosing patients w/ enthesitis-related arthritis
  • May indicate risk for the development of axial arthritis

Anti-cyclic Citrullinated Peptide (anti-CCP) Antibodies

  • May indicate severe disease but may not be advised in all patients

Others: double-stranded Deoxyribonucleic Acid (dsDNA), Extractable Nuclear Antigens (ENA), C3, C4 & Immunoglobulin (Ig)

  • May be helpful if the arthritis is part of an underlying connective tissue disease or vasculitis
  • Studies have showed that serum levels Ig correlate w/ disease activity & acute phase response

Imaging

  • Plain radiographs
    • Less costly, easily available & faster way to evaluate joints but limited & nonspecific for early
    • Juvenile idiopathic arthritis (JIA) changes
    • Helps identify erosions which is apparent in a disease of >3 months duration
    • May be used to rule out other diagnosis & to confirm clinical findings
    • Soft tissue swelling, periarticular osteoporosis & periosteal new-bone apposition around affected joints are the early radiographic changes of arthritis
    • Subchondral erosions, loss of cartilage, different degrees of bone destruction & bone fusion may be seen in X-rays of patients w/ continued active JIA
    • Serial X-rays may show disease progression & may indicate the need for change in patient’s management 
  • Ultrasound
    • May be used to confirm joint effusions, specifically in the hip & shoulder joints where fluid is often difficult to see clinically
  • Magnetic resonance imaging (MRI)
    • More sensitive to early changes than x-rays
    • Identifies inflammatory changes in the joint & damages in the cartilage, & assesses early changes in the soft-tissue
    • Also accurate in evaluating late manifestations of JIA (eg erosions, loss of joint space, damage in the cartilage & involvement of ligaments)
  • Technetium-99 bone scan
    • May also help in detecting early stage of inflammatory arthritis

JIA Treatment Group

  • Management of juvenile idiopathic arthritis (JIA) patients were based on their treatment groups since there are few evidence to support the differential treatment of children w/ JIA for different category distinctions
    • Based on patient’s disease activity level & presence or absence of poor prognostic features
     Juvenile Idiopathic Arthritis (JIA)  Treatment Group  Juvenile Idiopathic Arthritis (JIA)  Subtype Features of Poor Prognosis (must satisfy at least 1) Disease Activity Levels
    Low 
    (must satisfy all)
    Moderate
    (does not satisfy high or low criteria)
    High 
    (must satisfy at least 3)
    ≤4 joints throughout their disease course
    • Persistent oligoarthritis
    • Psoriatic arthritis
    • Enthesitis-related arthritis
    • Undifferentiated arthritis
    • Hip or cervical spine arthritis
    • Ankle or wrist arthritis & marked or prolonged increase in inflammatory markers
    • Erosions or joint space narrowing seen on X-ray
    • ≤1 active joints
    • Normal erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP) level
    • Physician (MD) global assessment1 of overall disease activity <3 of 10
    • Patient/parent global assessment2 of overall well-being <2 of 10
    • ≥1 features more than low disease activity level & <3 features of high disease activity
    • ≥2 active joints
    • ESR or CRP >2x upper limit of normal (ULN)
    • MD global assessment1 of overall disease activity ≥7 of 10
    • Patient/parent global assessment2 of overall well-being ≥4 of 10
    ≥5 joints throughout their disease course
    • Extended oligoarthritis
    • Rheumatoid factor (RF)-negative polyarthritis
    • Rheumatoid factor (RF)-positive polyarthritis
    • Psoriatic arthritis
    • Enthesitis-related arthritis
    • Undifferentiated arthritis
    • Hip or cervical spine arthritis
    • Positive RF or anti-cyclic citrullinated peptides (CCP) antibodies
    • Erosions or joint space narrowing seen on X-ray
    • ≤4 active joints
    • Normal ESR or CRP level
    • MD global assessment1 of overall disease activity <4 of 10
    • Patient/parent global assessment2 of overall well-being <2 of 10
    • ≥1 features more than low disease activity level & <3 features of high disease activity
    • ≥8 active joints
    • ESR or CRP >2x ULN
    • MD global assessment1 of overall disease activity ≥7 of 10
    • Patient/parent global assessment2 of overall well-being ≥5 of 10
    Active sacroiliac arthritis
    • Psoriatic arthritis
    • Enthesitis-related arthritis
    • May be any of the JIA subtype
    • Erosions or joint space narrowing seen on X-ray
    • Normal back flexion
    • Normal ESR or CRP level
    • MD global assessment1 of overall disease activity <4 of 10
    • Patient/parent global assessment2 of overall well-being <2 of 10
    • ≥1 features more than low disease activity level & <2 features of high disease activity
    • ESR or CRP >2x ULN
    • MD global assessment1 of overall disease activity ≥7 of 10
    • Patient/parent global assessment2 of overall well-being ≥4 of 10
    Systemic arthritis w/ active arthritis & w/o active systemic features Systemic arthritis w/ active arthritis
    • Hip arthritis
    • Erosions or joint space narrowing seen on X-ray
    • ≤4 active joints
    • Normal ESR or CRP level
    • MD global assessment1 of overall disease activity <4 of 10
    • Patient/parent global assessment2 of overall well-being <2 of 10
    • ≥1 features more than low disease activity level & <3 features of high disease activity
    • ≥8 active joints
    • ESR or CRP >2x ULN
    • MD global assessment1 of overall disease activity ≥7 of 10
    • Patient/parent global assessment2 of overall well-being ≥5 of 10
    Systemic arthritis w/ active systemic features & w/o active arthritis Systemic arthritis w/ active fever of systemic JIA w/ or w/o other systemic features & w/o active arthritis
    • 6 months duration of significant active systemic disease (eg fever, increased inflammatory markers, systemic corticosteroids required for the treatment)
    • Active fever & MD global assessment1 of overall disease activity <7 of 10
    • Active fever & systemic features of high disease activity that result in MD global assessment1 of overall disease activity ≥7 of 10

    Modified from: Beukelman T, Patkar NM, Saag KG, et al. 2011 American College of Rheumatology recommendations for the treatment of juvenile idiopathic arthritis: initiation and safety monitoring of therapeutic agents for the treatment of arthritis and systemic features. Arthritis Care & Research.2011;63:465-482.

    1Physician’s (MD) global assessment consists of rating the overall level of the child’s disease activity based on a 10 cm visual analogue scale (VAS): 0=no activity; 10=maximum activity
    2Parent’s global assessment consists of their rating on the child’s overall well-being based on a 10 cm VAS: 0=very good; 10=very poor

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