Endometriosis and autoimmunity: a large-scale case-control study of endometriosis and 10 distinct autoimmune diseases.

In this study, we assessed if women with endometriosis have greater odds than matched controls of receiving an autoimmune diagnosis within two-years of their endometriosis diagnosis. We conducted a retrospective cohort study using two large-scale administrative claims databases (2010-2017), identifying 332,409 patients with endometriosis and 1,220,932 matched controls. Compared to matched controls, patients with endometriosis had an increased risk of being diagnosed with rheumatoid arthritis, Hashimoto's disease, systemic lupus erythematosus, multiple sclerosis, pernicious anemia, Sjogren's syndrome or myositis within two-years of their endometriosis diagnosis. The odds of receiving a diagnosis of at least one of the autoimmune conditions among patients with endometriosis were approximately two times greater than matched controls. Our study is the first to show a significant association between endometriosis and autoimmune conditions within a two-year diagnosis window, adding to growing evidence suggesting a potential link between endometriosis and autoimmunity, warranting investigation into shared mechanisms.