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Autoimmune Diseases in Systemic Sclerosis Patients and Their Relatives: Data from a Single Center.

BACKGROUND
The aggregation of autoimmune diseases in relatives (AID-R) of patients with systemic sclerosis (SSc) has been reported.


OBJECTIVES
To analyze the prevalence of autoimmune diseases in SSc relatives and to compare their features to those of SSc patients without AID-R (controls).


METHODS
A case-control analysis compared SSc patients with AID-R to those without AID-R (25 patients) with similar disease duration.


RESULTS
Among 322 patients, 25 (7.7%; 21 females, 41.4 ± 15.6 years of age, disease duration 11 ± 8.6 years) had AID-R (21 had a first-degree relative, 4 had a second-degree relative, and 2 had both). Fourteen patients (56%) and five controls (20%) had an additional autoimmune disease (P < 0.009). Diffuse SSc (48% vs. 24%) and arthritis (72% vs. 28%) were more frequent among the patients with AID-R than the controls (P < 0.05). No significant differences were found regarding lung, heart, vascular, and digestive system involvement. The mean number of additional autoimmune diseases was 0.84 ± 0.94 in AID-R vs. 0.24 ± 0.52 in controls (P < 0.038). The mean number of autoantibodies was 2.8 ± 1.5 and 2.2 ± 0.9 (P < 0.047). Five patients died during follow-up, four of whom had AID-R. Relatives of SSc patients had diverse autoimmune diseases; the prevalence of SSc in scleroderma relatives was 1.86% (2 in first-degree and 6 in second-degree relatives). SSc patients with AID-R had an obvious tendency to polyautoimmunity.


CONCLUSIONS
A precise family history is an important clue in prognosis and prediction of autoimmune diseases in SSc patients and their relatives.