Background There are scarce data comparing clinical and serological features in patients with systemic sclerosis (SSc) and SSc overlap syndromes (SSc-OS) due to the rarity of these associations.
Objectives To analyze clinical and SSc-associated serological profiles including a panel of novel described antinucleolar antibodies (ANoA) in a large cohort of Brazilian patients with SSc and SSc overlap syndromes.
Methods Three-hundred twenty-eight SSc patients classified according to the ACR/EULAR 2013 SSc criteria, attended at the Scleroderma Outpatient Clinic of a tertiary referral university hospital from 2000 to 2011 were enrolled in the study; 32% had diffuse cutaneous SSc and 68% limited cutaneous SSc. Clinical and demographic data were obtained from an electronic register database. Serum samples were analyzed for the presence of antinuclear antibodies (indirect immunofluorescence on HEp-2 cells), antibodies to Scl-70, PM-Scl, RNA-Pol III, CENP-A/CENP-B, and Ro/SS-A (52 and 60 kDa) (ELISA), and antinucleolar antibodies (ANoA) fibrillarin, Ku, Th/To and NOR90 (line blot immunoassay) using commercial available standardized kits.
Results Two-hundred sixty eigth patients were classified as SSc and sixty patients as SSc-OS (14 with systemic lupus erythematosus, 11 with polymyositis, 7 with rheumatoid arthritis, and 35 with Sjogren Syndrome, isolated or combined). Both groups (SSc-O and SSc) were similar regarding mean age at onset, female predominance, disease duration and ethnicity (p>0.05). Concerning clinical features, there were no significant differences related to the occurrence of pitting scars, digital amputation, calcinosis, telangiectasia, interstitial lung disease, pulmonary hypertension, cardiovascular disease, renal crisis (p>0.05). Conversely, SSc-OS patients had lower mean modified Rodnan skin score (5.6±4.24 vs. 10±11.7, p<0,001),but higher percentage of joint (33 vs. 21%, p=0.04) and muscle involvement (22 vs. 8%, p=0.003) compared to the SSc group. There was no difference regarding the frequency of all autoantibodies tested in the two groups (p>0.05), except for the negative association among anti-RNA-Pol III with SSc-OS (p=0.011).
Conclusions This study identified a comparable occurrence of major organ involvement and ischemic lesions in SSc-OS and SSc. This finding is strengthened by the observation of a similar frequency of all scleroderma autoantibodies in both groups and suggests that SSc determines the clinical manifestation in overlap syndromes in spite of a less extensive skin involvement in these patients.
Disclosure of Interest None declared