Rheumatoid arthritis on the rise in women: study

NEW YORK (Reuters Health) - After 40 years of decline, the incidence of rheumatoid arthritis appears to be on the rise among women, according to research conducted at the Mayo Clinic in Rochester, Minnesota.

If this finding is confirmed, Dr. Sherine Gabriel told Reuters Health, it may "provide clues as to the environmental triggers that may contribute to the development of RA."

Dr. Gabriel presented her team's research this week in San Francisco at the American College of Rheumatology Annual Scientific Meeting.

"Our data is based on a unique data resource, the Rochester Epidemiology Project, which has been continuously funded by the National Institutes of Health for approximately 40 years," she explained. "It contains essentially complete medical information on all residents of Olmsted County, Minnesota, from the time they were born or the date they moved to Olmsted County, until the time they die or the date they move away."

Their analysis showed that between 1995 and 2005, 350 patients, nearly 70 percent of whom were women, were diagnosed with RA. The age-adjusted incidence in females was 54.0 per 100,000 population -- a significant increase over the incidence of 36.4 per 100,000 during the previous decade.

Among men, however, the age-adjusted incidence was almost unchanged (28.6 vs 29.5 per 100,000).

"The rapid change in incidence (among women) is suggestive of an environmental factor or factors," Gabriel noted.

The researchers are currently focusing on "disease severity in order to determine whether the increasing incidence reflects an added number of mild or of severe cases," she said.

"We will also try to examine risk factors in order to generate hypotheses about what might be behind this observed change in incidence," Gabriel added.

The rheumatologist emphasized that "these results are still preliminary and that much more work needs to be done to fully understand their impact."