Prevalence of Sjogren's syndrome in ambulatory patients according to the American-European Consensus Group criteria

Objective. To estimate the prevalence of Sjogren's syndrome (SS) in ambulatory patients attending a tertiary care centre, according to the American-European Consensus Group criteria, using a structured approach. Methods. Three hundred patients from rheumatology and internal medicine clinics were randomly chosen. During the screening phase, a face-to-face interview, a screening questionnaire, a Schirmer-I test and a wafer test were carried out in all patients. During the second phase, patients with positive screening had confirmatory tests including fluorescein staining test, non-stimulated whole salivary flow and autoantibody testing. Confirmatory tests were also done in 13 patients with negative screening. In the last phase, lip biopsy was proposed to those patients who met pre-established criteria. Results. Females constituted 79% of the study population. The mean age of the subjects was 42.8+/-15.7 yr. Two hundred and twenty patients (73%) had positive screening. Fifty-five (27%) out of 204 patients evaluated showed keratoconjunctivitis sicca and 28 (13%) out of 215 patients xerostomia. One hundred and sixty-eight patients met criteria for lip biopsy and it was performed in 80 subjects who accepted the procedure. Focal sialoadenitis was demonstrated in 39 patients (49%), but only 28 of them met criteria for SS. In total, 40 patients were classified as SS. The minimum prevalence of SS in the population studied was 13.3% (95% CI 9.5-17.1%). The structured approach used in this study allowed 24 (60%) undiagnosed cases of SS to be identified. Conclusion. SS is common among ambulatory patients attending a tertiary care centre and in most of them it is undiagnosed.