Rheumatoid arthritis (RA) is a painful autoimmune disease that affects about 1% of the population.1 A comprehensive epidemiological study of global disease burden in 2015 found that the prevalence of RA was about 25 million individuals, with an overall increase by 23.8% from 2005.2 RA usually causes bilateral joint pain, stiffness, and swelling, which is typically worse after periods of inactivity or in the morning. While RA is characterized by joint involvement, other inflammatory manifestations include fever, anemia of chronic disease, pericarditis, and pulmonary fibrosis. RA can also be associated with other autoimmune diseases, including systemic lupus erythematosus and psoriatic arthritis.
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