Objective: To study the seroprevalence of Helicobacter pylori (H. pylori) infection in patients with primary Sjögren's syndrome (SS), fulfilling the 1993 European classification criteria compared with three different control groups.
Methods: Serological tests investigating the presence of antibodies against H. pylori were performed by Enzyme Immuno Assay (EIA) and confirmed by immunoblot (IB). The samples were tested for antibodies against cytotoxin-associated-protein A (CagA). The three control groups included were: one simultaneously collected age-matched group of orthopaedic outpatients without rheumatological disease, a random primary care patient sample from the same geographic region and a group of age-matched blood donors.
Results: 45% of the SS patients (n = 164) were EIA-positive for H. pylori and 30% were positive in the confirming IB assay. 23% had antibodies to the CagA protein. We found a clear and statistically significant increase in seroprevalence with increasing age. These estimates were lower compared to the control group of orthopaedic patients but similar to those in the other two control groups, thus showing the importance of multiple control groups in case control studies. In the group of SS patients there were no significant associations between a positive EIA, IB or CagA for H. pylori and the presence of abnormal serum levels of autoantibodies (ANA, anti-SSA, anti-SSB, rheumatoid factor (RF)) or an abnormal lip biopsy.
Conclusion: Swedish patients with primary SS do not have higher H. pylori seroprevalence rates than controls. Neither was H. pylori seropositivity associated with the presence of immunological markers of SS such as circulating autoantibodies or a lip biopsy with abnormal focus score.