Accurate detection of changes in disease activity in primary Sjögren's syndrome by the European League Against Rheumatism Sjögren's Syndrome Disease Activity Index

Abstract

Objective: To assess and compare the sensitivity to change of the European League Against Rheumatism Sjögren's Syndrome Disease Activity Index (ESSDAI) with that of other primary Sjögren's syndrome (SS) disease activity indexes.

Methods: We abstracted 96 patient profiles, including data on 3 successive visits (visits 1-3), from the medical charts of patients with primary SS. Patient profiles were scored with the ESSDAI, SS Disease Activity Index (SSDAI), and Sjögren's Systemic Clinical Activity Index (SCAI). Thirty-nine experts assessed 5 profiles for whether disease activity had improved, worsened, or remained stable at visits 2 and 3.

Results: For improved patients, the standardized response means (SRMs) for all scores did not differ, and ranged from -1.08 to -1.38 between visits 1 and 2 and from -0.50 to -0.76 between visits 2 and 3. For patients with worsened activity, the SRMs between visits 1 and 2 and between visits 2 and 3 were +0.46 and +1.10 for the ESSDAI, -0.03 and +0.79 for the SSDAI, and +0.17 and +1.02 for the SCAI, respectively. For patients with stable activity, the SRMs between visits 1 and 2 and between visits 2 and 3 were 0.00 and -0.13 for the ESSDAI, -0.44 and -0.11 for the SSDAI, and -0.36 and +0.34 for the SCAI, respectively.

Conclusion: For patients with improved activity, the 3 disease activity indexes showed similar, large sensitivity to change. However, the ESSDAI seemed to detect changes in activity more accurately than other disease activity indexes. Notably, for patients with stable activity, the ESSDAI did not show erroneous improvement.