Prevalences of Other Non-Thyroid Autoimmune Diseases and Factor Associated with Their Presence in Ocular Myasthenia Gravis

To report the prevalences of other non-thyroid autoimmune diseases and identify factors associated with their presence in ocular myasthenia gravis (OMG) subjects. A total of 208 subjects with OMG diagnosis were included. Demographic data, clinical characteristics, the ice-pack test, the acetylcholine receptor (AChR) antibody test, electrophysiology tests (single-fiber electromyography and repetitive nerve stimulation), the presence of thymoma, generalized myasthenia gravis conversion, and the presence of other non-thyroid autoimmune diseases (defined as the presence of at least one other non-thyroid autoimmune disease) were retrospectively reviewed. Factors associated with the presence of other non-thyroid autoimmune diseases were analyzed by univariate and multivariate logistic regression. Of the total 208 subjects, 21 (10.10%) exhibited the presence of other non-thyroid autoimmune diseases (19 subjects (9.14%) and 2 subjects (0.96%) had one and two other non-thyroid autoimmune diseases, respectively), and systemic lupus erythematosus (SLE) was diagnosed in 9 subjects, followed by Sjogren's syndrome (7 subjects), rheumatoid arthritis (6 subjects), and ankylosing spondylitis (1 subject). Therefore, the prevalences of SLE, Sjogren's syndrome, rheumatoid arthritis, and ankylosing spondylitis in OMG subjects were estimated to be 4.33% (95% confidence interval (CI): 2.29-8.02%), 3.37% (95% CI: 1.64-6.79%), 2.88% (95% CI: 1.33-6.14%), and 0.48% (95% CI: 0.08-2.67%), respectively. Positivity of the AChR antibody was the only significant factor associated with the presence of other non-thyroid autoimmune diseases (odds ratio 4.10, 95% CI: 1.11-15.21, = 0.035). The presence of other non-thyroid autoimmune diseases was found in approximately 10% of OMG patients, with SLE displaying the highest prevalence. We recommend screening and monitoring for other non-thyroid autoimmune diseases in OMG patients, particularly those with positivity of the AChR antibody.