Muscular involvement in Sjögren's disease is associated with male gender, Ro52 autoantibodies, and a higher clinical activity.

Background: Sjögren's disease (SjD) is a systemic autoimmune disease that primarily affects exocrine glands. It can be associated with a variety of systemic manifestations, including myositis. At present, data evaluating muscular inflammation in SjD is limited, and further investigation is required. Methods: Patients with SjD and European Alliance of Associations for Rheumatology (EULAR) Sjögren's syndrome disease activity index (ESSDAI) muscular involvement (EMI) of at least six points in the muscular domain were recruited retrospectively from Hannover Medical School's SjD cohort after muscular inflammation was ascertained. Patients with SjD and EMI were characterised and compared with age- and sex-matched controls and with the entire SjD cohort. Results: A total of 26 of 492 SjD patients (5%) were diagnosed with EMI. The mean age of EMI onset was 56.4 years, the ratio between males and females was 12:14. Compared to SjD patients without EMI, SjD patients with EMI showed higher frequencies of Sjögren's Syndrome-related Antigen A/Ro(52) [SSA/Ro(52)] antibodies ( Conclusion: EMI is a rare but severe manifestation of SjD, occurring simultaneously with sicca symptoms. Male sex, positive SSA/Ro(52) antibodies, and high disease activity are more common in SjD patients with inflammatory myositis compared to those without muscular involvement.