Objectives: When Sjögren's syndrome (SS) is secondary to rheumatoid arthritis, the sicca syndrome is less serious and anti-SSA/SSB antibodies are found less frequently than in primary SS (pSS). When SS is associated with systemic lupus erythematosus, clinical and serological patterns are similar to those of pSS. We aimed to determine whether SS, accompanying systemic sclerosis (SSc), could be considered secondary to or associated with SSc and whether the coexistence of both modifies the severity and the outcome of each disease.
Patients and methods: A retrospective multicentric study was conducted to compare (i) characteristics and complications of SS between 27 patients with SS and SSc (SS-SSc) and 202 patients with pSS, and (ii) the characteristics of SSc and complications between the SS-SSc group and 94 patients with SSc alone.
Results: SS features were similar in both SS-SSc and pSS patients, except for peripheral neuropathy and arthritis, which was more common in SS-SSc than in the pSS patients (P = 0.02 and 0.05, respectively). SSc appears to be less severe in patients with SS-SSc than SSc alone with a lower frequency of lung fibrosis (P = 0.05). Compared with patients with pSS or SSc alone, SS-SSc patients were more likely to have another autoimmune disorder and other autoantibodies (SS-SSc vs pSS, P = 0.02 and P = 0.03, respectively).
Conclusion: SS seems to be associated with and not secondary to SSc. SS associated with SSc has the same features as pSS, but SSc seems to be less serious. Moreover, the association of SS and SSc is frequently accompanied by a spreading of autoimmunity.