Obesity and the painful autoimmune disorder rheumatoid arthritis are each becoming more common, raising a logical question: Could one have something to do with the other?
For women, it appears there is a link, Mayo Clinic researchers say. They studied hundreds of patients and found a history of obesity puts women at significant risk of developing rheumatoid arthritis. Their findings are published online in the American College of Rheumatology journal Arthritis Care & Research.
“We know that fat tissues and cells produce substances that are active in inflammation and immunity. We know too that obesity is related to many other health problems such as heart disease and diabetes, and now perhaps to autoimmunity,” says co-author Eric Matteson, M.D., Mayo Clinic rheumatology chairman. “It adds another reason to reduce and prevent obesity in the general population.”
In rheumatoid arthritis, the immune system attacks tissues, inflaming joints and sometimes also affecting other organs and causing fever and fatigue. Rheumatoid arthritis tends to initially impact the hands and feet and then spread to the knees, ankles, hips and shoulders. It is more common in women than in men. Complications can include heart problems, lung disease, osteoporosis and carpal tunnel syndrome.
To examine a potential link with obesity, researchers pulled medical records covering 1980–2007 from the Rochester Epidemiology Project and studied 813 adults with rheumatoid arthritis and 813 adults as the control group, matched by age, gender and calendar year. Height, weight and smoking status also were noted; roughly 30 percent of the patients in each group were obese and 68 percent were women.
Rheumatoid arthritis cases rose by 9.2 per 100,000 women from 1985–2007, the study found. Obesity accounted for 52 percent of the increase. Smoking also is a substantial risk factor for developing rheumatoid arthritis, but smoking’s prevalence remained constant over the years studied, ruling it out as an explanation for the rise in rheumatoid arthritis, the study found.
More research is needed to determine how obesity may lead to rheumatoid arthritis. The exact nature of the link between obesity and autoimmune diseases such as rheumatoid arthritis is not clear, Dr. Matteson says.
The study was funded by the National Institute of Arthritis and Musculoskeletal and Skin Diseases. Co-authors included biostatistician Cynthia Crowson, rheumatologist and epidemiologist Sherine Gabriel, M.D., and rheumatologist John M. Davis III, M.D., all of Mayo Clinic in Rochester.
WEB CHAT ALERT: Dr. Davis will be online May 1 from 11 a.m. to noon CT answering questions about rheumatoid arthritis as part of Arthritis Action Month. Go to the American College of Rheumatology’s Facebook page to take part.
VIDEO ALERT: Journalists can download sound bites of Dr. Matteson discussing the study on the Mayo Clinic News Network.
Really?? Are we going backwards here or what? I can’t even believe this is a real study! Obesity doesn’t cause RA. Did you forget that weight loss is supposed to be an RA symptom? I was a very fit bike commuter. People kept telling me I should model. But, oh obesity causes RA….. Did someone mess up somewhere? Are we talking Osteoarthritis?? You need to take these lies done off your web page. Instead of wasting time and money on this why don’t you find the cure researchers. Actually fire the ones who did this study. They clearly don’t know what research is.
Dr. Matteson responds:
RA can affect anyone, of any age, sex, body size or fitness level, as it clearly has unfortunately affected you.
The study finds a definite association between RA and obesity. Just as there is a definite association between smoking and RA, not everyone who smokes gets RA, and not everyone who gets RA is a smoker. Actually, most are not. However, there is a clear relationship, and like smoking, obesity is a (but clearly isn’t the only) risk factor for getting RA. We are only just beginning to understand how these risk factors are related to getting the disease. The immune mechanisms in RA are complex. Smoking alters the immune system in numerous ways, and so do fat cells.
You are very right that being overweight is hard on joints and is a risk factor for osteoarthritis. Managing one’s weight, and remaining fit, as you did, is really important to preserving joint health.
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