Infections increase the risk of developing Sjögren's syndrome

OBJECTIVE: Environmental factors have been suggested in the pathogenesis of rheumatic diseases. We here investigated whether infections increase the risk of developing primary Sjögren's syndrome (pSS).METHODS: Patients with pSS in Sweden (n=945) and matched controls from the general population (n=9,048) were included, and data extracted from the National Patient Register to identify infections occurring before pSS diagnosis during a mean observational time of 16.0 years. Data were analyzed using conditional logistic regression models. Sensitivity analyses were performed by varying exposure definition and adjusting for previous health care consumption.RESULTS: A history of infection associated with an increased risk of pSS (OR 1.9, 95% CI 1.6-2.3). Infections were more prominently associated with development of SSA/SSB autoantibody positive pSS (OR 2.7, 95% CI 2.0-3.5). When stratifying the analysis by organ system infected, respiratory infections increased the risk of developing pSS, both in patients with (OR 2.9, 95% CI 1.8-4.7) and without autoantibodies (OR 2.1, 95% CI 1.1-3.8), while skin and urogenital infections only significantly associated with development of autoantibody-positive pSS (OR 3.2, 95% CI 1.8-5.5 and OR 2.7, 95% CI 1.7-4.2). Furthermore, a dose-response relationship was observed for infections and a risk to develop pSS with Ro/SSA and La/SSB antibodies. Gastrointestinal infections were not significantly associated with a risk of pSS.CONCLUSIONS: Infections increase the risk of developing pSS, most prominently SSA/SSB autoantibody positive disease, suggesting that microbial triggers of immunity may partake in the pathogenetic process of pSS. This article is protected by copyright. All rights reserved