Consumer Information Center Rheumatoid Arthritis

Scientists estimate that about 2.1 million people, or 1 percent of the U.S. adult population, have rheumatoid arthritis. Interestingly, some recent studies have suggested that the overall number of new cases of rheumatoid arthritis may actually be going down. Scientists are now investigating why this may be happening.

Rheumatoid arthritis occurs in all races and ethnic groups. Although the disease often begins in middle age and occurs with increased frequency in older people, children and young adults also develop it. Like some other forms of arthritis, rheumatoid arthritis occurs much more frequently in women than in men. About two to three times as many women as men have the disease.

By all measures, the financial and social impact of all types of arthritis, including rheumatoid arthritis, is substantial, both for the Nation and for individuals. From an economic standpoint, the medical and surgical treatment for rheumatoid arthritis and the wages lost because of disability caused by the disease add up to millions of dollars. Daily joint pain is an inevitable consequence of the disease, and most patients also experience some degree of depression, anxiety, and feelings of helplessness. In some cases, rheumatoid arthritis can interfere with a person’s ability to carry out normal daily activities, limit job opportunities, or disrupt the joys and responsibilities of family life. However, there are arthritis self-management programs that help people cope with the pain and other effects of the disease and help them lead independent and productive lives. These programs are described later in the section Diagnosing and Treating Rheumatoid Arthritis.

Rheumatoid arthritis is one of several "autoimmune" diseases ("auto" means self), so-called because a person’s immune system attacks his or her own body tissues. Scientists still do not know exactly what causes this to happen, but research over the last few years has begun to unravel the factors involved.

Genetic (inherited) factors: Scientists have found that certain genes that play a role in the immune system are associated with a tendency to develop rheumatoid arthritis. At the same time, some people with rheumatoid arthritis do not have these particular genes, and other people have these genes but never develop the disease. This suggests that a person’s genetic makeup is an important part of the story but not the whole answer. It is clear, however, that more than one gene is involved in determining whether a person develops rheumatoid arthritis and, if so, how severe the disease will become.

Environmental factors: Many scientists think that something must occur to trigger the disease process in people whose genetic makeup makes them susceptible to rheumatoid arthritis. An infectious agent such as a virus or bacterium appears likely, but the exact agent is not yet known. Note, however, that rheumatoid arthritis is not contagious: A person cannot "catch" it from someone else.

Other factors: Some scientists also think that a variety of hormonal factors may be involved. These hormones, or possibly deficiencies or changes in certain hormones, may promote the development of rheumatoid arthritis in a genetically susceptible person who has been exposed to a triggering agent from the environment.

Even though all the answers aren’t known, one thing is certain: Rheumatoid arthritis develops as a result of an interaction of many factors. Much research is going on now to understand these factors and how they work together (see the Current Research section of this booklet).