Rheumatoid Arthritis (cont.)

Who Has Rheumatoid Arthritis?

Scientists estimate that about 1.3 million people, or about 0.6 percent of the U.S. adult population, have rheumatoid arthritis.1 Interestingly, some recent studies have suggested that although the number of new cases of rheumatoid arthritis for older people is increasing, the overall number of new cases may actually be going down.

1According to the National Arthritis Data Workgroup, the actual number of new cases of rheumatoid arthritis is lower than previous estimates because of changes in the classification for the condition, as cited in Helmick CG, Felson DT, Lawrence RC, Gabriel S, Hirsch R, Kwoh CK, Liang MH, Kremers HM, Mayes MD, Merkel PA, Pillemer SR, Reveille JD, Stone JH, for the National Arthritis Data Workgroup. Estimates of the Prevalence of Arthritis and Other Rheumatic Conditions in the United States. Part I. Arthritis and Rheumatism. 2008;58(1):15-25.

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.

What Happens in Rheumatoid Arthritis?

Rheumatoid arthritis is primarily a disease of the joints. A joint is the point where two or more bones come together. With a few exceptions (in the skull and pelvis, for example), joints are designed to allow movement between the bones and to absorb shock from movements like walking or repetitive motions. The ends of the bones are covered by a tough, elastic tissue called cartilage. The joint is surrounded by a capsule that protects and supports it (see illustration). The joint capsule is lined with a type of tissue called synovium, which produces synovial fluid, a clear substance that lubricates and nourishes the cartilage and bones inside the joint capsule.

Like many other rheumatic diseases, rheumatoid arthritis is an autoimmune disease (auto means self), so-called because a person's immune system, which normally helps protect the body from infection and disease, attacks joint tissues for unknown reasons. White blood cells, the agents of the immune system, travel to the synovium and cause inflammation (synovitis), characterized by warmth, redness, swelling, and pain -- typical symptoms of rheumatoid arthritis. During the inflammation process, the normally thin synovium becomes thick and makes the joint swollen and puffy to the touch.

As rheumatoid arthritis progresses, the inflamed synovium invades and destroys the cartilage and bone within the joint. The surrounding muscles, ligaments, and tendons that support and stabilize the joint become weak and unable to work normally. These effects lead to the pain and joint damage often seen in rheumatoid arthritis. Researchers studying rheumatoid arthritis now believe that it begins to damage bones during the first year or two that a person has the disease, one reason why early diagnosis and treatment are so important.

Some people with rheumatoid arthritis also have symptoms in places other than their joints. Many people with rheumatoid arthritis develop anemia, or a decrease in the production of red blood cells. Other effects that occur less often include neck pain and dry eyes and mouth. Very rarely, people may have inflammation of the blood vessels (vasculitis), the lining of the lungs (pleurisy), or the sac enclosing the heart (pericarditis).

A joint is a place where two bones meet. The ends of the bones are covered by cartilage, which allows for easy movement of the two bones. The joint is surrounded by a capsule that protects and supports it. The joint capsule is lined with a type of tissue called synovium, which produces synovial fluid, a clear substance that lubricates and nourishes the cartilage and bones inside the joint capsule.

Like many other rheumatic diseases, rheumatoid arthritis is an autoimmune disease (auto means self), so-called because a person's immune system, which normally helps protect the body from infection and disease, attacks joint tissues for unknown reasons. White blood cells, the agents of the immune system, travel to the synovium and cause inflammation (synovitis), characterized by warmth, redness, swelling, and pain -- typical symptoms of rheumatoid arthritis. During the inflammation process, the normally thin synovium becomes thick and makes the joint swollen and puffy to the touch.

Picture of rheumatoid arthritic joint
A joint (the place where two bones meet) is surrounded by a capsule that protects and supports it. The joint capsule is lined with a type of tissue called synovium, which produces synovial fluid that lubricates and nourishes joint tissues. In rheumatoid arthritis, the synovium becomes inflamed, causing warmth, redness, swelling, and pain. As the disease progresses, the inflamed synovium invades and damages the cartilage and bone of the joint. Surrounding muscles, ligaments, and tendons become weakened. Rheumatoid arthritis also can cause more generalized bone loss that may lead to osteoporosis (fragile bones that are prone to fracture).