Outcome measures for primary Sjögren’s syndrome

Lymphocytic infiltration of different exocrine and non-exocrine epithelia is the pathological hallmark of primary Sjögren's syndrome, whereas involvement of salivary and lachrymal glands with the clinical counterpart of dry eye and dry mouth 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, a core set of domains, which included sicca symptoms, objective measurements of tear and saliva production, fatigue, quality of life, disease activity and damage was indicated as essential for outcome assessment in this disorder. Afterwards, great efforts have been made to develop valid tools for the assessment of different domains. Specific questionnaires such as the Profile of Fatigue and Discomfort (PROFAD) and Sicca Symptoms Inventory (SSI) have been proposed as dedicated tools for the evaluation of patients symptoms, whereas different composite indexes have been suggested for the assessment of disease activity and damage. Some of these preliminary studies served as bases of an international project supported by EULAR, aimed at developing two 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. A detailed and critical review of all these indexes is provided in this article. Both EULAR indexes showed, in recent studies, to be feasible, valid, and reliable instruments. After their final validation, which is currently in process, they could be used as consensus outcome criteria in therapeutic trials and in clinical practice.