Lifetime risk of adult rheumatoid arthritis determined

"We estimated the lifetime risk for rheumatic disease for both sexes, something that had not been done before -- separately or collectively," says Cynthia Crowson Mayo Clinic biostatistician and first author. "Prevalence and incidence rates existed, but prevalence figures underestimate individual risk and incidence rates express only a yearly estimate."

The researchers were looking for an accurate basis to offer an easy-to-understand average risk over a person's lifetime, knowing that risk changes at almost every age. They used data from the Rochester Epidemiology Project, a long-term epidemiology resource based on patients in Olmsted County, Minn. The cohort of 1179, consisted of patients diagnosed between 1955 and 2007, allowed the team to extrapolate the nationwide estimates.

The adult lifetime risk in the United States of having some kind of inflammatory autoimmune disease is 8.4 percent for women and 5.1 percent for men. Based on year 2000 population figures, that means one woman in 12 and one man in 20 will develop one of the conditions in their lifetime. The authors consider that a substantial risk and say their findings should encourage more research on the value of early diagnosis and intervention for people with increased genetic risk of arthritis. They hope the new figures will help in counseling patients and in fundraising efforts to find improved treatments.

The research was supported by the National Institutes of Health. Other Mayo authors are Eric Matteson, M.D., M.P.H.; Elena Myasoedova, M.D., Ph.D.; Clement Michet, M.D.; Floranne Ernste, M.D.; Kenneth Warrington, M.D.; John Davis III, M.D.; Gene Hunder, M.D.; Terry Therneau, Ph.D.; and Sherine Gabriel, M.D.