COMMENTARY

Sjögren Syndrome: An A-to-Z Update

Robert I. Fox, MD, PhD; Carla M. Fox, RN

Disclosures

December 03, 2013

In This Article

Editor's note:
On October 25-30, 2013, the American College of Rheumatology (ACR) annual meeting was held in San Diego, California. More than 10,000 participants from 5 continents came to present papers on pathogenesis and therapy of rheumatic disease. This review will focus on presentations about the classification, pathogenesis, and therapy of Sjögren syndrome and will review presentations that have a particular emphasis on clinical practice and pathogenesis.

Growing Interest in Sjögren Syndrome

A steady growth in the number of abstracts and sessions devoted to Sjögren syndrome is apparent over the past decade of ACR meetings. It is encouraging that many pharmaceutical companies are now expressing interest in Sjögren syndrome as a therapeutic target. The dearth of effective therapies for systemic manifestations of Sjögren syndrome contrasts with the large number of therapies for rheumatoid arthritis and studies for psoriatic arthritis. Multiple sclerosis and fibromyalgia have also benefited from recently approved therapies.

Sjögren syndrome has shared the undesirable "distinction," along with scleroderma, of still being at the exploratory stage for targets. We are finally seeing new targets in both Sjögren syndrome and scleroderma, as genome-wide screens suggest potential targets.

Specific sessions at ACR were devoted to disease classification criteria, genetics, pathogenesis, and cytokines as well as to diseases such as immunoglobulin (Ig)G4-related disease (including Mikulicz syndrome).

The Classification Criteria Conundrum

At a special session sponsored by the Sjögren's Syndrome Foundation, the confusion over the current criteria for diagnosis continued to be debated.[1]

The American-European Consensus Group (AECG) criteria[2] and the Sjögren's International Collaborative Clinical Alliance (SICCA) criteria[1] were compared. Both sets of criteria are quite similar, with about 90% concordance. However, the 10% of patients who fulfill one set of criteria but not the other could influence the outcome of clinical studies.[2,3] The most important "child" of the AECG criteria is the European League Against Rheumatism Sjögren's Syndrome Disease Activity Index (ESSDAI).[4,5]

More than 1300 studies in well-defined cohorts in Europe have looked at the natural history, prognosis, and response to therapies.[6] Athough the 2 sets of criteria are 90% similar, the results of studies would be altered if a different entry criteria (SICCA rather than AECG) had been used.

The AECG criteria have become known to clinicians, pharmaceutical companies, and regulatory agencies as validated endpoints for research. Although it was clear that certain shortcomings (such as the use of rose bengal and the exclusion of IgG4-related disease) were present in AECG's original form, these modifications for multiple clinical trials during the past decade have easily been accomplished by selection of inclusion and exclusion criteria.

The SICCA cohort is a National Institutes of Health-funded international registry initially suggested in San Francisco (Daniels-California, and Shiboski-California) and subsequently in 5 academically based research groups located in Argentina, China, Denmark, and Japan under the direction of the University of California, San Francisco. Three groups from the United States joined in 2009. The question under discussion was whether the proposed SICCA criteria would improve the uniformity of patients enrolled for clinical trials.

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