Background Most data on the clinical associations of anti-RNA polymerase III (RNAP) antibodies in patients with Systemic Sclerosis (SSc) derive from single-center studies or relatively small positive case number reports.
Objectives To analyse the clinical associations of anti-RNAP in a large cohort of patients with different geographic and ethnic origin using the multicenter EUSTAR database.
Methods Patients from the EUSTAR database were included when the item anti-RNAP was fulfilled in at least one visit, and considered anti-RNAP+ when scored positive in at least one determination. In a second phase, EUSTAR centers were asked to participate to a case-control study, fulfilling a supplementary form dedicated to skin involvement progression, gastric antral vascular ectasia (GAVE), and malignancies. Malignancies diagnosed between 6 months before and 12 months after the onset of SSc were defined as “synchronous to the onset of SSc”. Centers were asked to match anti-RNAP+ cases with anti-RNAP- SSc controls, paired for sex, cutaneous subset, and disease duration. Univariate methods were used to compare patients with and without anti-RNAP.
Results Among 11,399 SSc patients registered in the EUSTAR database, 4,986 had anti-RNAP antibodies status available including 223 anti-RNAP+ (4.5%) and 4,763 anti-RNAP-. The differences between the two groups are shown in Figure 1. There was no difference as far as ethnicity (Caucasians: 94.2% vs 95.0%), age at disease onset, disease duration, length of follow-up, and other parameters included in the database. Ten centers participated in the case-control study, collecting 126 anti-RNAP+ cases (23% male, 59% with diffuse cutaneous involvement), and 137 anti-RNAP- matched patients. A trend toward a higher peak of modified Rodnan Skin Score (RSS) in anti-RNAP+ patients was observed (p:0.07). Interval time between the first symptom of SSc other than Raynaud's phenomenon and the peak of RSS was shorter in anti-RNAP+ cases than in controls (p:0.008; log-rank test). Other differences between the two groups are shown in Figure 1.
Conclusions Analysis of a large, multicenter database and a dedicated case-control study confirm that anti-RNAP is one of the most useful markers available to stratify SSc patients in subsets with peculiar clinical features. These include rapid progression of skin involvement, GAVE, and an increased risk of diagnosis of cancer simultaneous to the onset of SSc. This information should guide monitoring and follow-up in anti-RNAP+ SSc patients.
Disclosure of Interest None declared