WASHINGTON (Reuters) - Rheumatoid arthritis appears to be on the rise among U.S. women after four decades of retreat while remaining stable among men, researchers said on Saturday.
The condition, common in the wrist and fingers, is an inflammatory type of arthritis that leads to joint pain, swelling, stiffness and joint damage.
The rate of new cases of rheumatoid arthritis appearing annually in the United States declined from 1955 through 1994. The new study focused on data from 1995 through 2004.
The rate during this period was 54 new cases annually per 100,000 women, up from 36 per 100,000 from 1985 through 1994. The rate among men remained at about 29 new cases a year per 100,000 men, the researchers found.
"When the recent data is combined with the earlier data, it clearly shows that it's been increasing. It's significant, especially among the women. We need to find out what's causing this," Dr. Hilal Maradit Kremers, an epidemiologist with the Mayo Clinic in Minnesota, said in a telephone interview.
The researchers based their conclusions, presented at a meeting of the American College of Rheumatology in San Francisco, on data on a regional population in Minnesota.
The findings suggested that just about 1 percent of people in the United States had rheumatoid arthritis.
Reporting by Will Dunham; Editing by Julie Steenhuysen and John O'Callaghan