The prevalence of systemic lupus erythematosus in Lithuania: the lowest rate in Northern Europe

The aim of this study was to explore the prevalence of systemic lupus erythematosus (SLE) in Lithuania (Vilnius). Two different studies were designed for SLE cases identification: registry-based SLE study and population-based SLE study. For the registry-based study patients were enrolled during the period of 1999-2004 and from two sources, including out-patient clinics of Vilnius and tertiary rheumatology center with interview during the year 2004. Only Vilnius residents who fulfilled the ACR 1982 revised criteria for the classification of SLE were counted in this study. Seventy-six living adult patients with SLE were interviewed and accounted for the prevalence of 16.2/100 000 (0.016%) using the Vilnius adult population in January 2004 (a population of 470 45 1). The population study of randomly selected 10 000 Vilnius inhabitants with beforehand validation of the survey was performed in the same year. The population-based study revealed two cases for 4017 respondents, but the low response rate may be important. Extrapolating the results to population of 10 000 inhabitants, the point prevalence of SLE in the entire sample was at least 0.02%. Therefore, the prevalence of SLE in Lithuania is the lowest if compared to Northern European countries.