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UI researchers report smoking increases severity of rheumatoid arthritis

IOWA CITY, Iowa -- Cigarette smoking significantly worsens the symptoms of rheumatoid arthritis, according to University of Iowa College of Medicine researchers who studied the severity of the disease in more than 300 patients.

In a study published in the latest issue of the Annals of the Rheumatic Diseases, UI researchers, led by Dr. Kenneth Saag, assistant professor of internal medicine, report that smoking is a significant, modifiable risk factor for the severity of rheumatoid arthritis, a disease that affects more than two million Americans. Their findings imply that quitting smoking may influence the severity of the disease.

"Our study is the first that I know of to suggest smoking affects the severity of rheumatoid arthritis, so more research in this area is needed," Saag says. "But it appears likely that not smoking would benefit those people with rheumatoid arthritis."

Rheumatoid arthritis causes chronic inflammation and degeneration of the joints, typically those in the fingers, hands, feet, ankles, knees and shoulders. The condition is usually diagnosed by the presence of swollen joints, by X-rays that reveal erosion around the affected joints, and by the presence of antibodies in the blood known as rheumatoid factor.

In the study, UI researchers evaluated 336 patients who had first visited the UI rheumatology or orthopaedics clinics between 1985 and 1992. Patients were asked about their rheumatoid arthritis, medication use and other health factors, lifestyle and smoking habits. The patients also received blood tests, clinical evaluations and X-rays of their hands to measure the amount of bone erosion in those areas.

After adjusting for known risk factors for rheumatoid arthritis, such as age and gender (women are more likely to have the disease), the UI team found that the patients who had smoked in the past or were current smokers were more likely to have high levels of rheumatoid factor and were at an increased risk for bone erosion. Moreover, those who had smoked for more than 25 years had three times the rheumatoid factor and bone erosion risks of non-smokers.

Researchers are not sure how smoking specifically worsens the symptoms of rheumatoid arthritis, Saag says. "Smoking can cause abnormalities in the immune system of rheumatoid arthritis patients both in the lung as well as other parts of the body," he says. "Smoking increases a person's white blood cell count, and heavy smoking can cause abnormalities in immune system cells that may increase the risk of infection."

9/3/97