Primary Sjögren's syndrome (pSS) is characterized by a lymphocytic infiltration of exocrine glands. Involvement of salivary and lachrymal glands results in dry eye and dry mouth which are the predominant features of the disease, together with fatigue and musculoskeletal pain. In addition, systemic manifestations, like arthritis, skin vasculitis, peripheral neuropathy, glomerulonephritis, may also be present in a consistent number of patients. As result, Clinical features in SS can be divided into two facets: the benign subjective but disabling manifestations such as dryness, pain and fatigue, and the systemic manifestations.
In the past decades, great efforts have been made to develop valid tools for the assessment of theses both facets. Disease specific questionnaires such as Profile of Fatigue and Discomfort (PROFAD) and Sicca Symptom Inventory (SSI) have been proposed for evaluation of patients symptoms, whereas different composite indexes have been suggested for the assessment of systemic disease activity. Nevertheless, an international project supported by EULAR, emerged to develop consensus disease activity indexes: the EULAR Sjögren's Syndrome Patients Reported Index (ESSPRI), and the EULAR Sjögren's Syndrome Disease Activity Index (ESSDAI), a systemic activity index to assess systemic manifestations.
Both EULAR indexes have been developed by an international collaboration to be consensual. Both indexes have also been validated in a large independent international cohort. They both have been shown to be valid and reliable instruments. Also, the 2 scores have been shown not to correlate, suggesting that these 2 indexes assess 2 different disease components that poorly overlap, and are complementary. The sensitivity to change of both scores has been assessed, they are both able to detect change, however ESSDAI score, like other systemic score, seems to be more sensitive to change than ESSPRI and other patient scores.
The next steps have been to define disease activity levels and clinically important changes for defining significant clinical improvement with the systemic score ESSDAI, and ESSPRI. This increased knowledge on the way to assess patients with primary SS, along with the emergence of new targeted therapy, aims to put a great input in the improvement of conduction of clinical trials in pSS
Disclosure of Interest None declared