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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
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."