Different sets of diagnostic criteria have been proposed for Sjoegren's syndrome (SS), but none have been validated in a large series of patients or in multicentre studies. This European study, supported by the Epidemiology Committee of the EEC, involved 26 centres from 12 countries and its aim was to reach a consensus on the diagnostic procedures for SS and to define the diagnostic criteria to be used in epidemiological surveys and adopted in the scientific community.
Sjoegren's syndrome (SS) is defined as an autoimmune disease of the exocrine glands, involving in particular the salivary and lacrimal glands. It may occur alone (primary SS), or in association with a variety of connective tissue diseases (CTD) and autoimmune disorders (secondary SS) (1). The spectrum of presentation of the disorder is very broad, ranging from the local consequences of exocrine gland dysfunction to major, life-threatening systemic complications such as vasculitis, and renal or lung involvement. Furthermore, a significant proportion of patients with SS may develop malignant lymphoproliferative disorders such as B cell lymphoma or multiple myeloma. Although SS was once thought to be rare, recent data suggest that the prevalence of this condition may approach or even exceed that of rheumatoid arthritis, which affects between 1% and 3% of the general population. Up to now SS has been largely overlooked due both to its great variability at presentation and to the lack of well-defined and commonly accepted diagnostic criteria. In fact, several sets of criteria have been proposed and used by different authors, but these were usually formulated by experts on the basis of their experience in the field or else derived from data coming from a single centre.
The present study was performed in Europe and supported by the Commission of the European Community (EC-COMAC Epidemiology); the objective of the Concerted Action was to define and validate simple tools which may be used to measure the prevalence of SS in a general population, and to reach agreement on the diagnostic criteria for this disease, to be utilised both in epidemiological surveys and as a uniform language in the scientific community.
The study protocol was subdivided into two parts. For Part I questionnaires for both eye and oral involvement were drawn up; they included 13 and 7 questions, respectively. For Part II a limited set of diagnostic tests was selected, and the exact procedure to be followed in performing these tests was defined. Part I of the study was performed in 240 patients with primary SS and in 240 age- sex-matched controls. Two hundred and forty-six patients with primary SS, 201 with secondary SS, 113 with connective tissue diseases but without associated SS, and 133 control patients were collected for Part II.