Rheumatoid Arthritis Health Article

RHEUMATOID ARTHRITIS

Rheumatoid arthritis (RA) is an inflammatory disease of the joints, the cause of which is still unknown. Infectious factors are being studied, including bacterial and viral organisms, but no definite involvement of any agent has been proven. There are indications that some genetic patterns are present in higher frequencies in patients with rheumatoid arthritis. This seems related to an increased frequency in some families, but not beyond a fairly weak association.

The disease can start at any age, with the childhood type of inflammatory arthritis peaking at around age two. In adults it predominates in women (the prevalence being 2.5 times greater in women) and appears more often during the childbearing years. Studies done around the world show a frequency of 1 to 5 percent in most populations. Historically, some recognizable forms of arthritis have been found in Egyptian mummies, though rheumatoid arthritis is not one of them. Its major descriptions in the medical literature roughly coincide with the start of the industrial revolution.

The main feature of the disease is an inflammation of the synovial tissues inside the joints. Synovium is usually present as a thin specialized tissue responsible for the production of the fluid that lubricates the joint. In RA, the synovium becomes swollen and shows the presence of many inflammatory cells. There is an excessive production of fluid and joints become swollen, warm, painful, and difficult to move—both because of the pain and because of the presence of the fluid, whose volume in the confined space of the joint restricts motion. RA mainly involves peripheral joints and does not usually involve the spine. The small joints of the fingers (except for the terminal joints) and the bones of the wrist are typically involved.

Inflammation in the joints causes the release of destructive enzymes from the inflammatory cells that have been attracted to the synovial tissue. The enzymes also collect in the fluid. These enzymes, which are usually part of the body's defense against bacteria, find the tissues in the joint to be grist for their destructive activity, and they also attack the cartilage covering the joint surfaces. This destruction can continue into the bone, and the joint can be so damaged as to render it incapable of normal function.

In about 85 percent of patients with RA a protein is found in the blood called rheumatoid factor. Although it is present in high frequency and concentration in RA, it can be found in other diseases, and even occasionally in normal individuals. RA is not simply a joint disease but can involve many other organs and tissues, including the eye, skin, lungs, heart, and blood vessels throughout the body.

Although some children, mostly girls in their teens, can have RA, the disease in the very young usually involves only a few large joints (knees and ankles). There is, however, an unusual form that afflicts children with high intermittent fevers and an extensive rash.

Treatment of RA has changed drastically (for the good) in the past few years. Aspirin was the original analgesic, anti-inflammatory drug, and it has been used for RA for over one hundred years. Aspirin is a versatile drug, but the high doses required for inflammatory arthritis frequently lead to gastric irritation. Gold compounds were the initial disease-modifying anti-rheumatic drugs (DMARDs) and have been in use for about seventy years.

The next development, starting in the early 1960s, was a rapid surge of nonsteroidal anti-inflammatory analgesic drugs (NSAIDs), which provided more prolonged activity and less gastric irritation than aspirin. The latest type of NSAIDs have even fewer gastric irritating properties but are still potent. The DMARDs that came after gold were hydroxychloroquine, an antimalarial agent that is mildly anti-inflammatory, and sulfasalazine, also mildly anti-inflammatory.

More recently, the drug methotrexate, which has been used in cancer chemotherapy, was found to be anti-inflammatory, and it has been successfully used in the treatment of RA. A major advance came with the development of biologic compounds that specifically block a link in the inflammatory "cascade" of cell-stimulating proteins. One of these is an antibody to an early product in this cascade. It is given intravenously and is effective when given at six- to eight-week intervals. Another is a "blocking" agent given by subcutaneous injection twice a week. An antibody to the B-lymphocyte involved in inflammation is also being developed. These new therapies are based on a new understanding of inflammation, even though the cause of RA still eludes researchers.

JOHN BAUM

(SEE ALSO: Osteoarthritis)