Can rheumatoid factor be positive in Sjogren's syndrome?

Rheumatoid Factor in Sjögren's Syndrome

Yes, rheumatoid factor (RF) is frequently positive in Sjögren's syndrome, with studies showing RF positivity in up to 76-84% of patients with primary Sjögren's syndrome. 1, 2

Prevalence and Significance of RF in Sjögren's

• RF is commonly found in Sjögren's syndrome patients, with different isotypes present:

  • IgM RF: Positive in approximately 76% of patients 1
  • IgA RF: Positive in approximately 84% of patients 1
  • IgG RF: Also detected but at varying levels 3

• RF positivity occurs regardless of whether patients have glandular or extraglandular disease manifestations 1

• RF positivity in Sjögren's differs from RF in rheumatoid arthritis:

  • Sjögren's patients generally display higher IgA-RF concentrations 3
  • Rheumatoid arthritis patients typically have IgM-RF as the dominant isotype 3

Clinical and Prognostic Implications

• RF positivity in Sjögren's syndrome is associated with:

  • Higher disease activity as measured by ESSDAI scores 2
  • More severe conjunctivitis sicca 2
  • Higher erythrocyte sedimentation rate (ESR) 2
  • Higher gammaglobulin concentrations 2
  • Lower white blood cell counts 2

• RF-positive Sjögren's patients at diagnosis have a higher risk of developing extraglandular organ involvement over time 4

• RF often co-occurs with other autoantibodies in Sjögren's syndrome:

  • Positive correlation between RF and antinuclear antibodies (ANA) 2
  • Positive correlation between RF and anti-SSA/Ro antibodies 2
  • Positive correlation between RF and anti-SSB/La antibodies 2
  • 81% of Sjögren's patients are concordant for 3 of 4 antibodies tested (IgA RF, IgM RF, anti-Ro, anti-La) 1

Diagnostic Considerations

• While RF is common in Sjögren's, anti-SSA/Ro antibody positivity carries more diagnostic weight:

  • Anti-SSA/Ro antibody positivity is weighted 3 points in the ACR-EULAR classification criteria 5
  • RF is not included in the current classification criteria for Sjögren's syndrome 5

• IgA RF has shown potential as a diagnostic marker:

  • Sensitivity of 83.1% and specificity of 78.4% for primary Sjögren's syndrome 6
  • Associated with worse exocrine function and more active serologic profile 6

Clinical Pearls and Caveats

• RF should be considered more as a prognostic rather than diagnostic factor in Sjögren's syndrome 2

• When evaluating a patient with suspected Sjögren's syndrome, focus on the ACR-EULAR criteria which include:

  • Anti-SSA/Ro antibody testing
  • Focal lymphocytic sialadenitis on labial salivary gland biopsy
  • Ocular staining score
  • Schirmer test
  • Unstimulated salivary flow rate 5

• Be aware that RF positivity may indicate a more severe disease course and should prompt vigilant monitoring for extraglandular manifestations 4, 2

• RF positivity in Sjögren's syndrome does not necessarily indicate overlap with rheumatoid arthritis, as the pattern of RF isotypes differs between the two conditions 3