| Abstract
| - Background. Recently, the EULAR Sjögren’s Syndrome Disease Activity Index (ESSDAI) has been developed to measure clinical disease activity in patients with Sjögren’s syndrome.(1) In an open label trial with rituximab (RTX) we showed that the ESSDAI is sensitive to measure treatment efficacy in patients with primary Sjögren’s syndrome (pSS),(2) but data from a randomized controlled trials are not yet available. Objectives. To evaluate the responsiveness of the ESSDAI in pSS patients treated with RTX or placebo. Methods. In a randomized controlled trial, thirty patients with pSS, as determined by the revised American-European Consensus Group criteria, were treated with either RTX (1000 mg; n=20) or placebo infusions (n=10) on days 1 and 15. Follow-up was conducted at 5, 12, 24, 36 and 48 weeks after treatment. During all scheduled follow-up visits the ESSDAI was scored using the patient’s charts by an independent observer blinded for the treatment. The ESSDAI scores over time were analyzed with generalized estimating equations. Responsiveness of ESSDAI was assessed using standardized response mean (SRM) and effect size (ES). SRM and ES <0.5 were interpreted as small, between 0.5 and 0.8 as moderate and >0.8 as large. Results. The median (range) ESSDAI scores at baseline were 8.0 (4-13) and 6.5 (2-13) in the RTX and placebo groups, respectively. In the RTX group, the ESSDAI scores decreased significantly at week 5 to 36 after treatment and returned to baseline values at week 48. In the placebo group, the ESSDAI scores decreased significantly only at week 5, probably due to the use of corticosteroids to prevent side effects (125 mg i.v. given just before the RTX infusions, and 5 days oral prednisone (2 days 60 mg, 2 days 30 mg and 1 day 15 mg)) and were comparable to baseline values for all other time points (Figure 1). The ES and SRM for the ESSDAI in RTX group were large at weeks 5, 12, and 24, moderate at week 36 and small at week 48. In the placebo group, ES and SRM were moderate at week 5 and small at all other time points. Conclusions. The ESSDAI is a sensitive tool to measure disease activity changes in patients with pSS after RTX treatment. The present results support the use of the ESSDAI in future clinical trials. References. Seror R, Ravaud P, Bowman S, et al. EULAR Sjögren’s Syndrome Disease Activity Index (ESSDAI): development of a consensus systemic disease activity index in primary Sjögren’s syndrome. Ann Rheum Dis 2010;69:1103-9. Meiners PM, Arends S, Brouwer E, et al. Responsiveness of disease activity indices ESSPRI and ESSDAI in patients with primary Sjögren’s syndrome treated with rituximab. Ann Rheum Dis. 2011; 2012 Jan 17. [Epub ahead of print]. Disclosure of Interest. None Declared
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