The prevalence of rheumatoid arthritis in the general population of Spain

Abstract

Objective: To estimate the prevalence of rheumatoid arthritis (RA) in the adult Spanish population and to assess its distribution by basic sociodemographic characteristics.

Methods: Two thousand nine hundred and ninety-eight adults were selected randomly from the censuses of 20 municipalities. Trained rheumatologists administered a structured interview that included a screening questionnaire for RA. Subjects with a positive screening result were examined according to a standardized protocol. Cases were defined by the 1987 American College of Rheumatology (ACR) criteria adapted to epidemiological surveys.

Results: One hundred and eighty-six persons (8.5%) had a positive screening result for RA and 11 of these fulfilled the ACR criteria for RA. The estimated prevalence was 0.5% (95% confidence interval 0.25-0.85). The ratios of women to men and of urban to rural were both 4:1. Function and health perception of the cases were significantly impaired, even after controlling for age and sex.

Conclusion: The prevalence of RA in Spain is comparable to that in other Mediterranean countries. RA may be less frequent in rural settings, a finding that merits further research. A significant proportion of RA cases in the community remain undiagnosed despite impaired functional status.