[The existence of geographical clusters of rheumatiod arhritis according to their origin in a tertiary care based register].

The objective was to analyse epidemiological tendencies of rheumatoid arthritis (RA) in Dalmatia County in order to identify possible spatial clusters of RA. Patient-interviewers were trained to administer telephone surveys. 197 RA patients controlled at Rheumatology and immunology department of Clinical hospital of Split were mapped to place of residence by telephone survey. Statistical evidence of clustering was determined by calculating Poisson probabilities in putative areas. Four clusters were identified; the largest one was in the region of Sinj. The female/male ratio was 5.79:1. Majority of RA patients were among age 50 to 59 (30.45 %). The results show inter-regional variations with the marked clusters in the north of Dalmatia suggesting that clusters with higher incidence of RA have specific genetic and environmental background. Prevalence of RA in female was higher than in current literature, while the age of onset 50-59 years is similar with data from recent studies.