Anti-RA 33: A Marker of Good Prognosis in Seronegative Rheumatoid Arthritis

Objective: Autoantibodies are evident in the early stages of rheumatoid arthritis (RA) and play important roles in diagnosis. The aim of this study was to investigate the diagnostic capability and extent of anti-RA 33 positivity and clinical characteristics in patients with RA. Methods: We included 67 RA patients and 20 healthy subjects in our study. Duration of symptoms, duration of disease, the extent of delay in diagnosis, episodes of clinical remission, and type and number of disease-modifying antirheumatic drugs (DMARDs) taken were noted. To evaluate quality of life, the Health Assessment Questionnaire (HAQ) Disability Index (consisting of 20 questions) was applied. Disease activity was evaluated with Disease Activity Score (DAS) 28. The laboratory assessments included erythrocyte sedimentation rate, C-reactive protein level and serologic assessments for rheumatoid factor, anti-cyclic citrullinated protein and anti-RA 33. Results: The mean disease duration was 14.56 months. A total of 38 (56.7%) patients were positive for anti-RA 33 antibodies. Twenty-four (63%) ofpatients positive for anti-RA 33 were clinically in remission. A negative correlation was evident between anti-RA 33 positivity and number of DMARDs taken and HAQ score (r = 0,766, p < 0.001; r = -0.737, p < 0.001). A positive correlation was evident between anti-RA 33 positivity and DAS 28 score (r = 0.287, p = 0.019). Conclusion: Anti-RA 33 antibodies have poor diagnostic capability in patients with RA. AntiRA 33 antibodies may exert helpful effects determining prognosis in established RA patients.