Classification and diagnostic criteria in Sjögrens syndrome: a long-standing and still open controversy

Most rheumatic diseases are multisystem disorders that are heterogeneous in their presentation, course and outcome. These conditions still lack a single clinical, laboratory, pathological or radiological feature that could serve as a ‘gold standard’ in support of diagnosis and/or classification. Thus, the development of criteria for use in clinical care and research studies has been an important challenge in these disorders.1

From the theoretical and methodological point of view, classification and diagnostic criteria are quite different. Classification criteria are standardised tools that are aimed at selecting well-defined and homogenous groups of patients for research and at guaranteeing comparability across studies. They are not designed to be used for the clinical diagnosis in individual patients and may be defective in capturing some cases with a less common clinical presentation or course.2

Diagnostic criteria are generally less stringent and usually include a wider variety of disease features....