What is rheumatoid arthritis?
Rheumatoid arthritis (RA) is a chronic autoimmune disease that causes stiffness, pain, loss of mobility, inflammation, and erosion (deterioration) in the joints. It usually affects multiple joints symmetrically, the hand and wrists most commonly, but also elbows, neck, shoulders, hips, knees, and feet. Other symptoms include fatigue, fever, the development of nodules under the skin, especially at the elbows, and a sense of not feeling well (malaise). People with RA may develop anemia, systemic complications, and may have other co-existing autoimmune disorders and symptoms, such as the dry eyes and mouth associated with Sjögren syndrome.
Rheumatoid arthritis can affect anyone at any age, but it usually develops between the ages of 40 and 60. Over 70% of those affected are women. According to the National Institutes of Health, more than 1.3 million people in the United States have RA. Left untreated, RA can shorten a person's lifespan and can, within a few years, leave many of those affected too disabled to work. The course of RA and its prognosis are variable. It may develop and progress slowly or rapidly. It may go into remission in some people and, in a few, it may go away. Pregnant women with RA frequently have decreased symptoms during their pregnancy and worsened symptoms after giving birth.
RA is different from the most commonly seen form of arthritis: osteoarthritis. Osteoarthritis, also called degenerative joint disease, is associated with joint injury and with the aging process ("wear and tear"). RA is an inflammatory process that affects the lining of the joints (synovium). It usually occurs in a symmetrical way—if one knee is affected, the other knee also is affected. The disease may be partly inherited through genes, but other factors are probably involved, including some kind of a trigger for the gene, perhaps bacteria or viruses. The disease is not contagious, however. Some scientists also think that changes in certain hormones may promote RA in people with certain genes who have been exposed to the triggering agent.