What is the initial approach to diagnosing and treating a child with symptoms of JIA (Juvenile Idiopathic Arthritis) versus ARF (Acute Rheumatic Fever)?

Distinguishing JIA from ARF: Diagnostic and Treatment Approach

Terminology Clarification

JRA (Juvenile Rheumatoid Arthritis) and JIA (Juvenile Idiopathic Arthritis) are the same disease entity, with JIA being the current internationally accepted term that replaced JRA. 1 The nomenclature "JIA" was adopted by the International League of the Association for Rheumatology to replace both "juvenile chronic arthritis" (used in Europe) and "juvenile rheumatoid arthritis" (used in North America) under a single unified classification. 1

Diagnostic Criteria

JIA Diagnostic Requirements

• Arthritis onset before age 16 years 1, 2
• Symptoms persisting for at least 6 weeks 1, 3
• Diagnosis of exclusion - must rule out other known causes of arthritis 1, 2

ARF Diagnostic Considerations

ARF is not covered in the provided evidence, but the key distinction is that JIA requires excluding infectious and post-infectious causes (which would include ARF) before diagnosis. 1

Initial Diagnostic Workup

Laboratory Studies

• CBC with differential, ESR, and CRP to assess inflammation 4, 5
• These tests help differentiate inflammatory arthritis from mechanical causes and assess disease activity 4

Imaging Approach

• Plain radiographs remain important for narrowing differential diagnosis and evaluating growth disturbances 3
• Ultrasound is helpful for peripheral joint assessment of inflammation and guiding joint injections 3
• MRI is the most validated and sensitive technique for detecting early inflammatory changes and should be considered the modality of choice, particularly for axial skeleton involvement 3

Initial Treatment Algorithm for JIA

Oligoarticular JIA (≤4 joints)

First-line therapy:

• Scheduled NSAIDs are conditionally recommended as initial therapy 6
• Intraarticular glucocorticoid injections (IAGCs) are conditionally recommended as part of initial therapy 6
• Triamcinolone hexacetonide is strongly recommended as the preferred agent for intraarticular injection over other steroid types 6, 5
• Oral glucocorticoids are conditionally recommended AGAINST as initial therapy 6

Second-line therapy (inadequate response to NSAIDs/IAGCs):

• Conventional synthetic DMARDs are strongly recommended 6
• Methotrexate is conditionally recommended as the preferred agent over leflunomide, sulfasalazine, and hydroxychloroquine (in that order) 6, 7
• Subcutaneous methotrexate is preferred over oral for better bioavailability 7

Third-line therapy (inadequate response to DMARDs):

• Biologic DMARDs are strongly recommended after failure of NSAIDs/IAGCs and at least one conventional synthetic DMARD 6
• There is no preferred biologic agent 6

Polyarticular JIA (≥5 joints)

The British Society for Rheumatology recommends a more aggressive initial approach:

• DMARD therapy (specifically methotrexate) is recommended as initial therapy rather than NSAID monotherapy for all JIA patients 7
• This represents a departure from the step-up approach and reflects evidence that early DMARD therapy is crucial to prevent permanent joint damage 7

Treatment escalation:

• If inadequate response to methotrexate, adding a biologic agent (TNF inhibitor, abatacept, or tocilizumab) is recommended rather than switching to another DMARD 7

Systemic JIA (without Macrophage Activation Syndrome)

Initial therapy:

• NSAIDs are conditionally recommended as initial monotherapy 6
• Oral glucocorticoids are conditionally recommended AGAINST as initial monotherapy 6
• Conventional synthetic DMARDs are strongly recommended AGAINST as initial monotherapy 6

For inadequate response:

• IL-1 and IL-6 inhibitors are strongly recommended over conventional synthetic DMARDs for inadequate response to NSAIDs and/or glucocorticoids 6

Enthesitis-Related Arthritis (including sacroiliitis)

Initial therapy:

• NSAIDs are strongly recommended as first-line therapy 6, 4
• Physical therapy is conditionally recommended for those with or at risk for functional limitations 6, 4

For inadequate response to NSAIDs:

• TNF inhibitors are strongly recommended (for sacroiliitis) 6
• TNF inhibitors are conditionally recommended over methotrexate or sulfasalazine (for enthesitis) 6, 4
• Bridging oral glucocorticoids (<3 months) may be considered during initiation of therapy if high disease activity, limited mobility, or significant symptoms are present 6, 4

Critical Pitfalls to Avoid

• Do not dismiss insidious onset joint pain as simple overuse without ruling out inflammatory arthritis - early DMARD therapy is crucial to prevent permanent joint damage 4, 7
• Do not use prolonged oral glucocorticoids as monotherapy - they are only for short-term bridging (<3 months) 6, 4
• Do not delay diagnosis with excessive testing - late treatment can cause severe joint damage, impair skeletal maturation, and lead to disability 1
• Physical examination has limited reliability even when performed by experienced clinicians, emphasizing the importance of imaging for clinical decision-making 3

Treatment Monitoring

• Use validated disease activity measures to guide treatment decisions and facilitate treat-to-target approaches 6
• Consider poor prognostic features (involvement of ankle, wrist, hip, sacroiliac joint, TMJ; erosive disease; enthesitis; delay in diagnosis; elevated inflammation markers; symmetric disease) to guide treatment escalation 6