Rheumatoid arthritis is a chronic, autoimmune disease. It is an inflammatory type of arthritis which affects the joints. The disease also may have systemic effects, affecting other organs of the body. Symptoms of rheumatoid arthritis include joint pain, joint stiffness, joint inflammation and joint deformity. Fever, malaise, severe fatigue, and morning stiffness lasting more than one hour are also common symptoms associated with rheumatoid arthritis.
About 80 percent of rheumatoid arthritis patients test positive for rheumatoid factor (detected by a blood test). Approximately 20 percent of rheumatoid arthritis patients are classified as having "seronegative rheumatoid arthritis" because they lack rheumatoid factor.
With rheumatoid arthritis, there is a symmetrical pattern of affected joints. For example, both knees of a patient are usually affected rather than one knee.