THE PREVALENCE AND SEVERITY OF RHEUMATOID-ARTHRITIS IN OSLO - RESULTSFROM A COUNTY REGISTER AND A POPULATION SURVEY

The objective was (1) to examine the prevalence of rheumatoid arthriti s (RA) by a county patient register, (2) to cross-validate the registe r findings by a postal population survey, and (3) to estimate prevalen ces of disease subsets according to age, sex, and levels of physical d isability. The study was performed within a county setting in the city of Oslo with 356,486 inhabitants between 20 and 79 years of age. Prev alence estimates were calculated from a county patient register compri sing 1333 patients with RA and a population survey of 10,000 inhabitan ts. The overall prevalence of RA between 20 and 79 years was 0.437 (95 % CI 0.413, 0.461) after adjusting for the incompleteness of the regis ter by a factor of 1.17. Prevalences exceeding 1.0% was only found amo ng females over 60 years. The prevalence of RA with MHAQ scores greate r than or equal to 1.5 and greater than or equal to 2.0 (range 1-4) wa s 0.225 (95% CI 0.209, 0.243) and 0.099 (0.088, 0.111) respectively. W e conclude that RA is less frequent in the city of Oslo than stated in most of the literature. The prevalence of RA with physical disability levels assumed to be associated with increased mortality is less than half of the overall prevalence of 0.4-0.5%.