RA is a chronic disease marked
by inflammation in the joints that causes pain, swelling and loss of mobility.
It is an autoimmune disease, meaning it arises from an abnormal immune
system attack on the body's own tissue.
Researchers from the Mayo Clinic
believe that environmental factors may play a role in causing RA to become
less common.
Researchers reviewed medical
records of Rochester residents to investigate trends in RA incidence and
mortality between 1955 and 1994. The average age at diagnosis of RA remained
the same over the study period, at 58 years.
Overall and by gender, the
incidence rate of RA declined progressively over time, the researchers
note. The overall incidence fell from
61.2 people with RA per 100,000 in 1955-1964 to 32.7/100,000 by 1985-1994.
The incidence fell more markedly in women than in men.
Survival in RA patients was
significantly lower than in the general population, the investigators
note, with these patients facing a 27% increased risk of death. Survival
remained "nearly identical" over time.
The incidence of RA appears
to be declining, and the findings suggest that an environmental factor
may play a role in its cause.
Arthritis
& Rheumatism March 2002;46:625-631
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