Primary Sjögren's syndrome as a systemic disease: A study of participants enrolled in an international Sjögren's syndrome registry

Objective: To study the prevalence of extraglandular manifestations in primary Sjögren's syndrome (SS) among participants enrolled in the Sjögren's International Collaborative Clinical Alliance (SICCA) Registry. Methods: A total of 1,927 participants in the SICCA registry were studied, including 886 participants who met the 2002 American-European Consensus Group (AECG) criteria for primary SS, 830 "intermediate" cases who had some objective findings of primary SS but did not meet AECG criteria, and 211 control individuals. We studied the prevalence of immunologic and hematologic laboratory abnormalities, specific rheumatologic examination findings, and physicianconfirmed thyroid, liver, and kidney disease, as well as lymphoma among SICCA participants. Results: Laboratory abnormalities, including hematologic abnormalities, hypergammaglobulinemia, and hypocomplementemia, frequently occurred among primary SS cases and were more common among the intermediate cases than among control participants. Cutaneous vasculitis and lymphadenopathy were also more common among primary SS cases. In contrast, the frequency of physician-confirmed diagnoses of thyroid, liver, and kidney disease and lymphoma was low and only primary biliary cirrhosis was associated with primary SS case status. Rheumatologic and neurologic symptoms were common among all SICCA participants, regardless of case status. Conclusion: Data from the international SICCA registry support the systemic nature of primary SS, manifested primarily in terms of specific immunologic and hematologic abnormalities. The occurrence of other systemic disorders among this cohort is relatively uncommon. Previously reported associations may be more specific to select patient subgroups, such as those referred for evaluation of certain neurologic, rheumatologic, or other systemic manifestations.