What are the key clinical features to consider when diagnosing Juvenile Idiopathic Arthritis (JIA) in a child?

Key clinical features for diagnosing Juvenile Idiopathic Arthritis (JIA) in a child include:

• Persistent arthritis: Swelling, pain, or limitation of movement in one or more joints lasting for at least 6 weeks, not explained by other causes, is the hallmark feature NICE CKS.
• Joint involvement pattern: Oligoarthritis (≤4 joints) is common, often affecting large joints such as knees and ankles, but polyarthritis (≥5 joints) can also occur NICE CKS.
• Morning stiffness and reduced range of motion: Children often present with stiffness, especially in the morning or after periods of inactivity, which improves with movement NICE CKS.
• Systemic features: Some subtypes of JIA may present with systemic symptoms such as fever, rash, lymphadenopathy, hepatosplenomegaly, or serositis, which should raise suspicion NICE CKS.
• Absence of other causes: Diagnosis requires exclusion of other causes of arthritis such as infection, trauma, malignancy, or other rheumatological conditions NICE CKS.
• Laboratory and imaging findings: While no single test confirms JIA, inflammatory markers (ESR, CRP) may be elevated; ANA positivity is common in oligoarticular JIA; imaging (ultrasound or MRI) can detect synovitis and joint damage early Dimitriou et al. 2017.
• Age of onset: Typically presents before 16 years of age, with peak incidence between 1 and 3 years for oligoarticular subtype NICE CKS.

Integrating UK clinical guidelines with recent literature emphasizes the importance of a thorough clinical assessment focusing on persistent joint inflammation and exclusion of other diagnoses, supported by targeted laboratory and imaging investigations to confirm synovitis and guide management Dimitriou et al. 2017Ruperto et al. 2021.