Rheumatoid arthritis is on the upswing among women

After four decades on the decline, rheumatoid arthritis is on the upswing among women in the United States. That's the finding presented by Mayo Clinic investigators at the annual meeting of the American College of Rheumatology/Association of Rheumatology Health Professionals in San Francisco.

"This is a significant finding and an indicator that more research needs to be done to better understand the causes and treatment of this devastating disease," says Sherine Gabriel, M.D., Mayo Clinic rheumatologist and lead investigator on the study.

From 1955 to 1994, the incidence of rheumatoid arthritis had continually been on the decline. That apparently changed beginning in the mid-1990s. When Mayo researchers analyzed patient data from early 1995 to the start of 2005, they found that both the incidence and prevalence (percentage) of the condition were rising.

Compared to the previous decade when approximately 36 women out of every 100,000 developed rheumatoid arthritis each year, the new study showed a jump to 54 women in the more recent decade. The incidence for men remained at about 29 per 100,000. Overall, the percentage of the entire population with the condition rose from 0.85 percent to 0.95 percent.

Researchers say it's not clear why this is happening, but an environmental factor may have a role in the shifting incidence and prevalence among women.

The study included 350 adult patients from Olmsted County, MN, whose average age was 56.5 years. The majority, 69 percent, were women.