http://www.mayoclinic.org/news2012-rst/6843.html

Mayo Clinic: Obesity Epidemic Fueling Rise in Rheumatoid Arthritis Among
Women

Wednesday, April 25, 2012

ROCHESTER, Minn. — 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 and Research.

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, says co-author Eric
Matteson, M.D., chair of the Division of Rheumatology at Mayo Clinic in
Rochester.

"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," Dr. Matteson says. "It adds another reason to
reduce and prevent obesity in the general population."

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.