What are the diagnostic criteria for rheumatic fever?

Diagnostic Criteria for Rheumatic Fever

The diagnosis of acute rheumatic fever requires evidence of preceding Group A Streptococcal infection plus either two major criteria, or one major and two minor criteria according to the Jones Criteria, which remain the accepted standard for diagnosis. 1, 2

Major Criteria

• Carditis - Clinical and/or subclinical (detected by echocardiography) 1, 2

  • Echocardiographic criteria for mitral regurgitation: jet in 2 planes, >1 cm, holosystolic, velocity >2.5 m/s 2
  • Echocardiographic criteria for aortic regurgitation: jet in 2 planes, holodiastolic, velocity >2.5 m/s 2

• Arthritis 1, 2

  • Low-risk populations: Polyarthritis only
  • Moderate/high-risk populations: Monoarthritis or polyarthritis
  • Moderate/high-risk populations: Polyarthralgia (after excluding other causes)

• Sydenham's Chorea - Involuntary, purposeless movements 1, 3

• Erythema Marginatum - Characteristic evanescent rash with clear centers and rounded edges 1, 2

• Subcutaneous Nodules - Firm, painless nodules over bony prominences 1, 2

Minor Criteria

• Fever 1, 2

  • Low-risk populations: ≥38.5°C
  • Moderate/high-risk populations: ≥38°C

• Arthralgia 1, 2

  • Low-risk populations: Polyarthralgia
  • Moderate/high-risk populations: Monoarthralgia (when not counted as major criterion)

• Elevated Acute Phase Reactants 1, 2

  • Low-risk populations: ESR ≥60 mm/hr and/or CRP ≥3.0 mg/dL
  • Moderate/high-risk populations: ESR ≥30 mm/hr and/or CRP ≥3.0 mg/dL

• Prolonged PR interval on ECG (after accounting for age variability, unless carditis is a major criterion) 1, 2

Evidence of Preceding Group A Streptococcal Infection

One of the following must be present 1, 3:

• Positive throat culture for Group A Streptococcus
• Positive rapid Group A Streptococcal antigen test
• Elevated or rising streptococcal antibody titers (anti-streptolysin O, anti-DNase B)

Special Considerations

• Recurrent Rheumatic Fever - In patients with previous rheumatic fever or established rheumatic heart disease, the diagnosis requires: 2 major criteria, or 1 major and 2 minor criteria, or 3 minor criteria 1, 2

• Population-Based Risk Stratification - Different diagnostic thresholds exist for low-risk versus moderate/high-risk populations 1, 4

  • Low-risk: ARF incidence ≤2 per 100,000 school-aged children or rheumatic heart disease prevalence ≤1 per 1,000 population
  • Moderate/high-risk: Higher prevalence regions

• Role of Echocardiography - Echocardiography is now recommended for all patients with suspected ARF 1, 4

  • Subclinical carditis detected by echocardiography is considered a major criterion in all populations 1, 2
  • Helps differentiate pathological from physiological valve regurgitation 1, 5

• Diagnostic Challenges 2, 6

  • Differentiate from post-streptococcal reactive arthritis (PSRA)
  • Exclude other diseases when using monoarthritis or polyarthralgia as criteria
  • Distinguish from Lyme disease, serum sickness, and drug reactions

• "Possible" Rheumatic Fever - In cases of diagnostic uncertainty with high clinical suspicion, consider prophylactic antibiotics for 12 months followed by reevaluation 2, 6

Pitfalls to Avoid

• Overdiagnosis in low-risk populations where other conditions may mimic ARF 7, 3
• Underdiagnosis in high-risk populations due to strict adherence to criteria 5, 6
• Failure to document preceding streptococcal infection 1, 3
• Misinterpreting physiological valve regurgitation as pathological on echocardiography 1, 2
• Relying solely on echocardiographic findings without clinical correlation 1, 5