Juvenile Idiopathic Arthritis Flashcards
What is juvenile idiopathic arthritis?
Group of systemic inflammatory disorders affecting children below the age of 16
Most commonly diagnosed rheumatic disease in children
Important cause of disability and blindness
What is the pathogenesis of juvenile idiopathic arthritis?
Autoimmune disease
Aetiopathogenesis is multi-factorial and different from that of adult RA
Strong subset-specific genetic markers may affect the immune response
What are the criteria for diagnosis of juvenile idiopathic arthritis?
Age of onset < 16 years Duration of disease > 6 weeks Presence of arthritis - joint swelling or 2 of - painful or limited joint motion - tenderness - warmth
After 6 months of JIA, 3 major subtypes can be identified, what will these help to identify?
Natural history
Complications
Prognosis
Strategy of treatment
What are the 3 major clinical subtypes of JIA?
Enthesopathy-related arthritis
Juvenile psoriatic arthritis - oligo or spondylo with psoriasis or potential psoriasis
Others - unclassified under above criteria
What is pauciarticular JIA?
4 or less joints involved
Most common type - accounts for 55% of JIA
What percentage of JIA is accounted for by;
Type 1
Type 2
Type 3
pauciarticular JIA?
Type 1 - 25%
Type 2 - 15%
Type 3 - 15%
What are the features of type 1 pauciarticular JIA?
Majority of pauci Onset < 5 years Peak at 1-3 years Girls:boys 8:1 Positive ANA in 40-75%
What is the clinical presentation of type 1 pauciarticular JIA?
Presentation of limping rather than pain
No constitutional manifestations
Mainly lower limb joints
Knee > ankle > hand or elbow
Hip very rarely affected
Chronic uveitis in 20% of cases, 95% of females < 2 years
Asymptomatic in 50%
Irregular iris due to posterior synechiae
What are the features of type 2 pauciarticular JIA?
15% of pauci
Onset after age 8-9
Girls:boys 1:7
What is the clinical presentation of type 2 pauciarticular JIA?
Mainly lower limb joints affected - knee and ankle
Hip can be affected early with rapid damage requiring THR early in life, may also have enthesitis and may have affected sacro-iliac joints, may evolve AS or spondyloarthritis
Those with HLA-B27 and back involvement will be categorised as juvenile ankylosing spondylitis
20% difficult to classify to a particular spondyloarthropathy group
Acute iridocyclitis in 10-20%
What are the features of type 3 pauciarticular JIA?
15% of pauci
Onset at any age during childhood
Girls:boys 4:1
What is the clinical presentation of type 3 pauciarticular JIA?
Constitutional presentation rare
Presents with asymmetric upper limb and lower limb arthritis, dactylitis
Arthritis may be very destructive
Family history of psoriasis in 40%
Nail pitting
Patients may develop psoriasis later in life
What percentage of children presenting with pauciarticular JIA go on to develop a more severe polyarticular course?
30%
What is polyarticular JIA?
5 or more joints affected
Second most common type - 25%
What are the features of rheumatoid factor negative polyarticular JIA?
15% of JIA
Onset at any age, often early
Girls:boys 9:1
What is the clinical presentation of rhuematoid factor negative polyarticualr JIA?
Constitutional manifestations e.g. low grade fever, malaise
Hepatosplenomegaly, mild anaemia, growth abnormalities
Iridocyclitis rare
Symmetric large and small joints affected - knees, wrists, ankles, MCPs, PIPs, neck
What are the features of rheumatoid factor positive polyarticular JIA?
10% of JIA
Onset in late childhood-teens, 12-16
Girls:boys 7:1
What is the clinical presentation of rheumatoid factor positive polyarticular JIA?
Constitutional manifestations e.g. low grade fever, malaise, weight loss
Anaemia
Nodules
Iridocyclitis rare
Can be complicated by Sjogren’s, Felty or vasculitis, AR, pulmonary fibrosis, AAS, CTS
Similar to adult RA
Erosions in x-ray occur early
What are the features of systemic onset JIA (Still’s disease)?
Least common - 20%
Most serious short and long term morbidity and mortality
Age throughout childhood 4-6 years
Girls:boys 1.5:1
What is the clinical presentation of systemic onset JIA?
Extra-Articular features define the disease, start early and disappear after 2-5 years
50-75%
- generalised lymphadenopathy
- non-tender
- hepatosplenomegaly
- abdominal pain
- +/- transaminases
75%
- within 3-12 months of onset of fever
- wrists, knees, ankles, cervical spine, hips and TMJ
90%
- evanescent salmon red eruption on trunk and thighs
- accompanies fever
- can be brought on by scratching (positive Koebner’s phenomenon)
Rise to 39.5 degrees C, daily for at least 2 weeks, late in the afternoon, returning to normal/sub-normal in the morning
Child appears toxic with fever +/- chills but appears normal when fever goes away
What are the rare clinical presentations of systemic onset JIA?
Pleural effusion Pulmonary fibrosis Polyserositis Pericarditis in 36% Tamponade and myocarditis
What are the investigations for JIA?
ASO - often elevated with no evidence of recent strep infection
ESR - often elevated, very high in systemic JIA, does not correlate with disease activity
ANA - 40-60% of pauciarticular JIA +ve
Rheumatoid factor - 15-20% of children with late onset polyarticular JIA
What is the first line treatment of JIA?
Simple analgesia
NSAIDs
- can control disease
- difference between adult and child half-life, same compounds but different doses
What is the second line treatment of JIA?
Systemic steroids
Joint steroid injections if no response to NSAIDs
Rarely needed in oligoarticular JIA
Methotrexate
Anti-TNF therapy in methotrexate failure
IL-1 R-antagonist (anakinra) in refractory systemic arthritis
IL-6 antagonist (tocilizumab) for refractory systemic disease
What are the indications for use of systemic steroids?
Limited indications due to serious side effects
- systemic JIA to control pain and fever
- serious disease complications with any subtype e.g. pericardial effusion, tamponade, vasculitis, severe autoimmune anaemia, severe eye disease
- as a bridge between DMARDs
- children undergoing surgery
What are the risks of systemic steroid use?
Osteoporosis
Infections
Growth abnormalities
What are the other treatment options for JIA?
Local steroids
- intra-articular, mainly in oligo-articular JIA
- eye disease (ANA +ve oligo-articular disease)
Topical steroids
- rehabilitation, phsyio, OT
Surgical treatment
- synovectomy
- reconstructive/joint replacement surgery
