Rheumatoid arthritis is an autoimmune disease that causes chronic inflammation of the joints, typically affecting the small joints in the hands and feet. It results in warm, swollen, and painful joints and symptoms often worsen with rest. While the cause is unknown, it involves the immune system attacking the synovium lining of joints, causing swelling and damage over time. Diagnosis involves evaluating symptoms, physical exam findings, and blood tests for rheumatoid factor or anti-CCP antibodies. Complications can include joint deformity and damage, as well as increased risk of osteoporosis, carpal tunnel syndrome, heart and lung problems.