Diagnosis of Sjögren's syndrome: American-European and the American College of Rheumatology classification criteria.

Classification criteria provide a formalized approach to studying course and management of rheumatic disease, as well as a measure of improvement in care. Understanding the purposes of classification criteria sets and the differences between different classification criteria is crucial for understanding rheumatic disease and for the design and conduct of clinical and epidemiologic investigations. In this article, the similarities and differences between the American-European Consensus Group Criteria (AECG) and the newly proposed American College of Rheumatology (ACR) classification criteria for Sjögren's syndrome and the clinical implications of switching to the ACR classification criteria from the AECG are described.