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What Is Rheumatoid Arthritis?

Rheumatoid arthritis is a relatively common disorder affecting 2.1 million Americans. It begins usually between ages 20 and 50, and women are affected three times as frequently as men. It may occur in children, particularly girls, from 2 to 5 years of age.

Rheumatoid arthritis is characterized by inflammation and pain in the hands — especially the knuckles and second joints — as well as in the arms, legs, and feet, and by general fatigue and sleeplessness. But it can affect almost any joint in the body. It can also cause damage to other parts of the body, including the heart, lungs, eyes, nerves and muscles. The discomfort of rheumatoid arthritis can develop over weeks or months and tends to be most severe on awakening.

Rheumatoid arthritis may eventually cause the hands and feet to become misshapen as muscles weaken, tendons shrink and the ends of bones become abnormally enlarged. Some of this deformity can be lessened with appropriate treatment.

While there is no complete cure, treatment begun at the onset of the disorder relieves symptoms in most people. With early treatment, the likelihood of permanent disability is reduced in all but 5% to 10% of sufferers.

What Causes It?

The cause of rheumatoid arthritis is not fully understood, though most research shows that it is an autoimmune disorder — meaning that the body's immune system is attacking one or more areas of the body. One theory suggests that it is an immune reaction to a viral or bacterial infection somewhere in the body. Some people have a genetic or inherited factor that makes them more likely to develop rheumatoid arthritis.