Rheumatoid arthritis (RA) is an autoimmune disease, in which the body’s immune system mistakenly attacks the joints. This creates inflammation that causes the tissue that lines the inside of joints to thicken and results in swelling and pain in and around the joints. If inflammation goes unchecked, it can damage cartilage, as well as the bones themselves. Over time, there is loss of cartilage, and the joint spacing between bones can become smaller. Joints can become loose, unstable, painful and lose their mobility. Joint deformity also can occur. Joint damage cannot be reversed, and because it can occur in early adulthood, doctors strive to diagnosis the disease and start treatment to control RA as early as possible.

Rheumatoid arthritis most commonly affects the joints of the hands, feet, wrists, elbows, knees and ankles. The joint effect is usually symmetrical. That means if one knee or hand if affected, usually the other one is, too. Because RA also can affect body systems, such as the cardiovascular or respiratory systems, it is called a systemic disease (involving the entire body).

About 1.5 million people in the United States have rheumatoid arthritis (RA). Nearly three times as many women have the disease as men. In women, RA most commonly begins between ages 30 and 60. In men, it often occurs later in life. Having a family member with RA increases the odds of having RA; however, the majority of people with RA have no family history of the disease.