What is the prevalence of autoimmune diseases in the general population?
Any organ system can be affected by autoimmunity. Presently there are over 80 autoimmune diseases with at least half of them considered rare. It is estimated that 4.5% to 5.3% of the population (14.7–23.5 million) have one or more autoimmune disease. Approximately 40% of these patients (2% of the population) have an autoimmune rheumatic disease. Of all patients with an autoimmune rheumatic disease, about half will have rheumatoid arthritis and half will have one of the other autoimmune rheumatic diseases (e.g. SLE, polymyositis).