Prevalence and incidence of systemic lupus erythematosus in the adult population of Estonia.

Studies have demonstrated considerable variability in systemic lupus erythematosus (SLE) incidence and prevalence estimates. Lack of reliable epidemiological data may hinder evidence-based health care planning. The aim of the present study was to estimate the prevalence and incidence of SLE in the Estonian adult population. The SLE billing cases were extracted from the Estonian Health Insurance Fund database 2006-2010 and verified using health care providers' databases. The patients' life status data for January 1, 2011, were retrieved from the Estonian Population Register. The calculations for the estimates' lower limits were based on verified cases only; the upper limits calculations also accounted for the billing cases for which clinical data were unavailable. The period prevalence of SLE was between 39 and 48 per 100,000 and incidence rate between 1.5 and 1.8 per 100,000 person-years. The point prevalence on January 1, 2011, was between 37 and 40 per 100,000. The estimates are comparable with internationally published figures and can be used to enhance evidence-based health care planning. The high percentage of billing cases that could not be verified using clinical data supports the argument that epidemiological studies based solely on administrative databases are usually of low reliability.