To evaluate the influence of lifestyle factors on the prevalence of rheumatoid arthritis (RA) by comparing Roman Catholic nuns and the general female population.
RA prevalence in the general population was evaluated using a standardized telephone survey in 1857 homes taken at random. Individuals who reported an inflammatory joint disease were contacted by a rheumatologist of our unit, missing data were collected from the general practitioner or rheumatologist with the patient's permission, and if necessary a physical examination was done by a rheumatologist. The 9 largest Roman Catholic nun communities in Brittany were screened using the same standardized questionnaire administered face-to-face; nuns who reported an inflammatory joint disease were interviewed and examined by rheumatologists. In both populations, RA was diagnosed when (1) the rheumatologist of our unit who interviewed the patient considered the RA classification criteria positive and (2) the rheumatologist who examined the patient gave a diagnosis of RA independently from RA classification criteria.
Data were available for 1706 adult females in the general population and 721 nuns. Of the 20 nuns who reported RA or polyarthritis, 11 received a diagnosis of RA (prevalence 1.52%). The prevalences adjustedfor the French population after 40 years were 1.66% (95% confidence interval, 0.84-2.44) and 1.33 (0.27-2.40) among the nuns and the general female population, respectively.
Although our nun population was too small for definite conclusions, we found no evidence of a difference in RA prevalence among nuns and the general female population in Brittany.