Collaborative research into outcome measures in Sjögren's syndrome

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Abstract
Sjögren's syndrome (SS) is a multisystem immune-mediated disorder characterized by inflammation of exocrine glands leading to clinical symptoms of dryness, particularly of the eyes and mouth which can be severe and disabling. It can occur in association with other rheumatic disorders or as a primary entity (PSS), often associated with B-cell hyperreactivity manifested by hypergammaglobulinaemia and anti-Ro and/or anti-La autoantibodies. These patients are more likely to have systemic involvement, for example of the pulmonary, neurological or haematological systems, and have a 44 times increased risk of non-Hodgkins lymphoma, this being the major adverse outcome in this disorder. Clinical trials of new therapies in disorders such as rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) have been advanced by the development of internationally agreed assessment and outcome measures such as the American College of Rheumatology/EULAR core datasets of disease activity in RA and measures of activity and damage in SLE such as BILAG, SLEDAI, SLICC etc. No such equivalent consensus exists for SS and as a result clinical trials have all used different, unvalidated, ad hoc measures of disease assessment and outcome. One attempt to bring a coherent approach to this issue is the "Copenhagen model" or disease assessment wheel that places each disease manifestation within specific categories depending on their presumed pathogenesis. Attempts have also been made to develop this into a severity tool by grading specific manifestations according to severity. In March 2000, interested specialists from around Europe met to develop a consensus on the broad principles underpinning disease assessment in SS (particularly PSS). It was agreed to adopt the international approach of dividing assessment into: exocrine and-nonexocrine disease activity (potentially reversible and including sicca symptoms and objective measures and systemic symptoms (particularly fatigue) and clinical features), damage (present for over 6 months), health-related and generic quality of life, and standard approaches to adverse events/toxicity and health economic aspects. The workshop also began the process of developing specific measures of sicca symptoms and systemic activity and damage. In order to convert this approach into detailed, experimentally validated assessment tools, a UK-based collaboration has focused on the development of systemic and sicca symptom questionnaires and a prospective evaluation in Europe of systemic activity and damage measures is planned.