Rheumatoid factor by laser nephelometry and Waaler-Rose assay: prognostic value in patients with recent-onset rheumatoid arthritis

Scand J Rheumatol. Jul-Aug 2005;34(4):269-76. doi: 10.1080/03009740510018606.

Abstract

Objective: To evaluate the prognostic value of rheumatoid factor (RF), detected in the Waaler-Rose agglutination assay and by nephelometry, in patients with recent-onset rheumatoid arthritis (RA).

Methods: Consecutive patients with new-onset RA between 1993 and 1997 were followed for a median period of 4.7 years. Clinical data at baseline and drug use during the disease course were recorded. Outcome parameters studied were disease process, damage (erosions, joint surgery, extra-articular manifestations, and new co-morbidity), and death. Cut-off levels for RF were >40 IU/mL (nephelometry) and titres 1:160 (Waaler-Rose haemagglutination).

Results: RF tests were negative by both methods in 22% of RA patients (RF- group), while 33% were RF positive by nephelometry only (RF+ group) and 45% were positive by Waaler-Rose and nephelometry (RF++ group). Baseline clinical and laboratory findings as well as the number of subsequently used disease-modifying anti-rheumatic drugs (DMARDs), the number of patients starting and the time spent on steroid therapy were similar in the three RF groups. Odd ratios for death (n = 23), erosions (n = 62), and serious extra-articular disease manifestations (EAMs) (n = 13) as well as patient survival, erosion-free or surgery-free survival rates did not differ between the RF groups. Only rheumatoid nodules were more frequent in RF++ patients.

Conclusion: The baseline presence of RF by either Waaler-Rose or nephelometry was not associated with differences in drug therapy, morbidity other than rheumatoid nodules, or mortality in RA patients in the first 5 years of disease. Being immunoglobulin M (IgM) RF positive thus had little impact on RA patient outcome.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Agglutination Tests / methods
  • Antirheumatic Agents / therapeutic use*
  • Arthritis, Rheumatoid / diagnosis*
  • Arthritis, Rheumatoid / drug therapy*
  • Arthritis, Rheumatoid / mortality
  • Biomarkers / analysis
  • Cohort Studies
  • Confidence Intervals
  • Disease Progression
  • Female
  • Humans
  • Logistic Models
  • Male
  • Middle Aged
  • Multivariate Analysis
  • Nephelometry and Turbidimetry / methods
  • Norway
  • Prognosis
  • Retrospective Studies
  • Rheumatoid Factor / analysis*
  • Rheumatoid Nodule / diagnosis
  • Rheumatoid Nodule / drug therapy
  • Rheumatoid Nodule / mortality
  • Risk Factors
  • Sensitivity and Specificity
  • Severity of Illness Index
  • Survival Rate
  • Time Factors
  • Treatment Outcome

Substances

  • Antirheumatic Agents
  • Biomarkers
  • Rheumatoid Factor