EPIDEMIOLOGY OF SJOGRENS-SYNDROME, ESPECIALLY ITS PRIMARY FORM

During the last decades different sets of criteria have been used for defining primary Sjogren's syndrome. Using these criteria prevalence e stimates have varied between 0.04 % - 4.8 %. This hundred-fold distrib ution in estimated frequency is partly due to differences in age group s studied, classification criteria used and methods used for objective evaluation of lachrymal and salivary gland hypofunction. Another prob lem which makes comparison between studies difficult is that workshop recommendations for the various objective tests are very often not str ictly followed. Population based studies tend to identify cases with l ess severe disease and higher prevalence rates. Furthermore, there see ms to be little correlation between dryness symptoms reported by subje cts and objective hypofunction of lachrymal and/or salivary glands, Po ssible explanations to these findings include selection bias towards m ore severe cases in clinical (university) studies and a low predictive value for some criteria in population studies.