History and exam
Key diagnostic factors
common
presence of risk factors
Female sex, human leukocyte antigen polymorphisms, and family history of autoimmunity are common risk factors for JIA.
more than 6 weeks' duration
Objective arthritis in joints for at least 6 weeks is necessary for diagnosis.
joint pain
Affected joints can be painful, especially during motion and on palpation.
joint swelling
Commonly at the knees in oligoarticular JIA and may be the presenting symptom. Examination of affected joints may reveal oedema. Synovial effusions and thickening are frequent findings.
fever
High-spiking fevers are commonly observed in systemic-onset juvenile idiopathic arthritis (SoJIA) but are not usual in other subtypes. One or 2 spikes of fever a day interspersed by normal temperatures, occurring daily for at least 2 weeks, is necessary for diagnosis of SoJIA.
Other diagnostic factors
common
age under 6 years
The majority of children with JIA present at a young age. However, the condition can occur at any time before the age of 16 years.
Oligoarticular and rheumatoid factor (RF)-negative polyarticular JIA usually present before the age of 6 years.
Enthesitis-related and RF-positive polyarticular JIA are usually seen in older children.
Systemic-onset JIA can occur at any age (including adulthood).
morning stiffness
Stiffness upon waking or after periods of inactivity is typical of JIA. Parents often describe their children as having stiff gaits in the mornings, which improve after a few hours when lower extremity joints are involved.
In children wearing nappies, parents may report reluctance for the child to have a nappy change first thing in the morning.
limp
Often more pronounced in the mornings and may be the presenting symptom when lower extremity joints are involved, or may become evident upon gait assessment.
limited movement
In active disease, limitation is often secondary to pain. In long-standing disease, limitation can be secondary to joint contractures that are due to ligament/tendon tightening.
rash
Evanescent, non-pruritic, non-fixed, erythematous rashes frequently occur in systemic-onset juvenile idiopathic arthritis (SoJIA). The rashes are salmon-coloured and commonly seen on the trunk and proximal extremities. They are not typically seen on palms, soles, or the face. Rashes often co-occur with fevers. The rash can be elicited by scratching the skin (Koebner's phenomenon). Psoriatic rashes may be evident in psoriatic arthritis.
Rash is a key factor if SoJIA is suspected.
enthesitis
Inflammation of the entheses (sites of tendon and ligament insertions to bone) is a common feature of enthesitis-related JIA (entheses around the knee and ankle are typically involved).
uncommon
limb length discrepancy
Growth disturbances are evident in long-standing, active, asymmetrical disease. This is typically observed in oligoarticular JIA with unilateral knee involvement. In these cases, the affected lower extremities tend to be longer than those on the contralateral side.
uveitis
Chronic non-granulomatous anterior uveitis is seen in about 10% of patients. It is often associated with a subset of patients who are young, female, and have antinuclear antibody positivity. Because uveitis is often asymptomatic, regular ophthalmological examinations are important. Systemic, rheumatoid factor-positive, polyarticular, and enthesitis-related subtypes are not typically associated with chronic anterior uveitis. Patients with enthesitis-related JIA are at risk for acute symptomatic anterior uveitis.
rheumatoid nodules
Nodules on extensor surfaces of tendons can be seen in rheumatoid factor-positive polyarticular JIA. These nodules are not observed in other subtypes.
Risk factors
strong
female sex
human leukocyte antigen (HLA) polymorphism
Several polymorphisms in the HLA region have demonstrated consistent associations with JIA.[12]
family history of autoimmunity
Extended multiplex families with JIA are relatively rare. However, positive family history of autoimmune disorders is relatively common.
In a study of 110 families of JIA probands, 74% had at least one relative with autoimmunity compared with only 33% of families of control probands.[20]
First- and second-degree relatives of children with JIA have a threefold increase in the prevalence of autoimmunity, particularly autoimmune thyroid disease.[20] This increase appears to be more pronounced in female relatives of mothers compared with that of fathers.[21]
The prevalence of JIA probands among siblings is 15 to 30 times higher than the population prevalence.[14][15][16]
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