Anti-RNA Polymerase III Antibody Prevalence and Associated Clinical Manifestations in a Large Series of French Patients with Systemic Sclerosis: A Cross-sectional Study

Objective. To determine the prevalence of anti-RNA polymerase III autoantibodies in French patients with systemic sclerosis (SSc) and to identify the associated clinical manifestations. Methods. Consecutive patients with SSc seen in 3 tertiary centers in Paris were included. Sera samples were collected together with the relevant clinical and immunological data. Anti-RNA polymerase III antibodies were detected by ELISA at a central laboratory. Data on other antibodies were abstracted from the medical records. Results. We included 319 patients: 84% women, 36% with a diffuse cutaneous subtype, 44% with pulmonary fibrosis, 5% with pulmonary hypertension, 4% with renal crisis, among whom 29 (9.4%) had anti-RNA polymerase 111 antibodies. These antibodies were more prevalent in patients with diffuse than with limited cutaneous disease (14.3% vs 6.0%; OR 2.6, 95% CI 1.2-5.48, p = 0.016). Renal crisis was more prevalent in patients with than in those without anti-RNA polymerase III antibodies (14% vs 3%: OR 5.0,95% CI 1.4-17.3, p = 0.012). Renal crisis occurred in 2.2% of patients with anti-topoisomerase I and 3.9% of patients with anticentromere antibodies. Of the patients with anti-RNA polymerase 111 antibodies, 24 (83%) had no other systemic sclerosis-specific autoantibodies. Conclusion. The prevalence of anti-RNA polymerase III antibodies in French patients appeared to be lower than in the United States and similar to that in continental Europe. These antibodies were consistently associated with diffuse cutaneous disease and were the most common immunological marker for renal crisis. Anti-RNA polymerase III determination can help to risk-stratify SSc patients at high risk for this severe manifestation. (First Release Nov 15 2009; J Rheumatol 2010;37:125-30; doi:10.3899/jrheum.090677)