The frequency of antibodies against cyclic citrullinated peptides and rheumatoid factor in healthy population: a field study of rheumatoid arthritis from northern Turkey.

Rheumatoid arthritis (RA) is a chronic, systemic and an autoimmune disease characterized by inflammation of the synovial membrane that affects approximately 1 % of the total world population. Rheumatoid factor (RF) is a widely used auto antibody in diagnosis of the RA and found positive in 50-80 % of the patients but with a lower specificity. On the other hand, anti-cyclic citrullinated peptide (anti-CCP) is the latest serological marker with a specificity around 98 %. This field survey was conducted in different regions to investigate the frequency of RF and anti-CCP and also frequency of RA in a northern province of Turkey. This study was conducted in 70 local areas (12 urban and 58 rural) in the province of Tokat, which is located in northern Turkey. The population of Tokat was reported to be 828,000 at the last census and about 530,000 individuals aged > 18 years old. The study population of 941 subjects (462 male and 479 female; urban 501 and rural 440) was selected by random sampling method among 530,000 individuals. Of the 941 healthy controls assigned to the study, 479 of them were female (51 %) and 462 of them were males (49 %), and median age of all participants was 41 ± 17. Twenty-six subjects were RF positive (2.8 %), and 9 patients were anti-CCP positive (1 %). The presence of both RF and anti-CCP antibodies has also been shown in two patients (0.2 %). In conclusion, we demonstrated that the frequency of RA was 0.53 %, RF presence was 2.8 %, and anti-CCP presence was 1 % in total 941 healthy subjects enrolled into study.