EULAR Sjogren's syndrome disease activity index: development of a consensus systemic disease activity index for primary Sjogren's syndrome.

Abstract Objective\u2014To develop a disease activity index for patients with primary Sj\uf6gren\u2019s syndrome (SS): the European League Against Rheumatism (EULAR) Sj\uf6gren\u2019s Syndrome Disease Activity Index (ESSDAI). Methods\u2014Thirty-nine SS experts participated in an international collaboration, promoted by EULAR, to develop the ESSDAI. Experts identified 12 organ-specific \u201cdomains\u201d contributing to disease activity. For each domain, features of disease activity were classified in 3 or 4 levels according to their severity. Data abstracted from 96 patients with systemic complications of primary SS were used to generate 702 realistic vignettes for which all possible systemic complications were represented. Using the 0\u201310 physician global assessment (PhGA) scale, each expert scored the disease activity of 5 patient profiles and 20 realistic vignettes. Multiple regression modelling, with PhGA used as the dependent variable, was used to estimate the weight of each domain. Results\u2014All 12 domains were significantly associated with disease activity in the multivariate model, domain weights ranged from 1 to 6. The ESSDAI scores varied from 2 to 47 and were significantly correlated with PhGA for both real patient profiles and realistic vignettes (r=0.61 and r=0.58, respectively, p