Objectives: To review the work pertaining to rheumatoid arthritis (RA) morbidity in Finland and to compare the data with that available from other countries.
Methods: Extensive investigations in Finland of the epidemiology of RA, based on nationwide registers designed primarily for administrative purposes and on extensive population studies, frequently in combination.
Results: According to several surveys with somewhat different study designs, the prevalence of clinically significant RA is about 0.8% of the adult Finnish population. Five national health interviews from a 30-year period have revealed figures about 50% higher, but with no clear change in prevalence. The incidence of clinically significant RA is about 40 per 100,000 of the adult population, which is in accordance with the prevalence figures. The mean age at diagnosis increased by 7.6 years from 1975 to 1990. Between 1978 and 1980, 5.8% of the severe disability in the adult Finnish population was attributable to RA. Some evidence suggests that severe disability resulting from RA diminished during the 1980s, possibly because of joint replacement surgery.
Conclusions: Monitoring sickness insurance statistics is a useful means of following the epidemiology of RA.