Encountering more plot twists than a Stephen King mystery, medical scientists are still baffled by the cause of a crippling disease that quietly strikes millions of Americans.

Arthritis, the swelling of the joints or other of the body's connective tissues, was once considered the sentence of only old age. One out of every five house-bound adults suffers from the disease, and it is the culprit blamed for the loss of 27 million work days a year.That's where doctors of rheumatology come in. Robert Willkens has spent his entire professional career looking at inflamed joints.

"My mother used to think I did a bad thing because I was a rheumatologist," he said. But he chose the specialty in order to take care of a patient's whole illness.

Willkens, a clinical professor of medicine at Seattle's University of Washington, was in Salt Lake City Tuesday to preach early prevention in the treatment of crippling rheumatoid arthritis. He praised rheumatologists at the University of Utah, who, led by Dr. John Ward, are conducting extensive arthritis drug studies.

With rheumatoid arthritis, the membrane lining of joints becomes inflamed. In extreme cases, the inflammation can progress to destroy the bones or cause deformity and eventual disability. A symptom of the disease is persistent joint pains that a night's rest won't ease. The disease usually strikes upper extremities on both sides of the body. Onset of the disease often occurs in the 30s or 40s, and three-fourths of its sufferers are women.

Early intervention, in the form of new drugs and surgery, may provide a higher quality of life for arthritis suffers and their loved ones, Willkens said. "It's not just the individual that gets arthritis, it's the whole family."

Although aspirin is the most common treatment, considered the first-team offensive against the disease, it isn't always the most effective. And while it may ease pain, doctors are discovering the prevalence of side affects such as ulcers or gastric irritation.

Second-line treatments include much stronger drugs, including the promising methotrexate, which was originally developed as a cancer treatment but appears to be an effective therapy for rheumatoid arthritis.

Rest, regular moderate exercise or physical therapy and diet are also considered important in controlling arthritis. Recently, fish oil has been touted as a miracle cure for heart and vascular disease as well as curing arthritis. Willkens said eating fish is part of a healthy lifestyle Willkens said sufferers can receive more information about the disease by calling the Arthritis Foundation's new toll-free information line at 1-800-283-7800.