Abstract

During the past decades a number of studies have examined the incidence of rheumatoid arthritis (RA) in different geographical settings and at different times. Some studies from the 1970s and 1980s reported a higher incidence of RA than seen during recent years, where reported incidence numbers seems to have flattened out at a lower level. Besides a real time dependent decline of RA incidence, changing methodology in classification may be an equally important explanation. Today we may assume that annually 25–50 people from a population of 100 000 will develop typical RA.