The prevalence of rheumatoid arthritis in an urban population of Izmir-Turkey.

OBJECTIVE To estimate the prevalence of rheumatoid arthritis (RA) in an urban area in Izmir, Turkey. METHODS The study was conducted in the Balcova and Narlidere districts of Izmir and a total of 2,887 people aged 20 years or older were contacted with a 98.2% acceptance rate. Nine medical doctors administered an RA questionnaire by face-to-face interview. Subjects reporting a history of swelling in at least 2 joints lasting more than 4 continuous weeks or a history of a diagnosis of rheumatoid arthritis, inflammatory joint rheumatism or joint rheumatism were considered as screening positive and they were invited to come in for an examination. RA cases were defined by the 1987 American College of Rheumatology (ACR) criteria modifiedfor use in population studies. RESULTS A total of 301 subjects (243 women, 58 men), or 10.6% of those who received the questionnaire were screening positive. 240 (79.7%) of these agreed to undergo a clinical examination either in the clinic or at home. Among these, 14 (12 female, 2 male) patients fulfilled the ACR criteria for RA. The prevalence of RA was 0.49% (95% CI 0.27-0.83) in the total population interviewed, 0.77% (95% CI 0.40-1.35) in women and 0.15% (95%CI 0.02-0.60) in men. The age- and sex-adjusted prevalence for the general population was estimated as 0.36%. Five of the 14 RA (36%) cases had not been diagnosed previously CONCLUSION These data are consistent with the results of other Mediterranean countries. A significant proportion of RA cases remain undiagnosed in the community.