Objective The assessment of disease activity in patients with Systemic Lupus Erythematosus (SLE) represents an essential need for clinical practice and clinical trials. Nevertheless, the validation of a sensitive and reproducible instrument remains a challenge for the rheumatologist due to SLE heterogeneity. SLE-DAS (SLE Disease Activity Score), a recently proposed index, demonstrated higher sensitivity to change in comparison to SLEDAI-2k. However, few studies have tested its performance in the assessment of treatment efficacy. Thus, we aimed at assessing the efficacy of subcutaneous (sc) belimumab (BLM) by SLE-DAS in a monocentric SLE cohort. In particular, we evaluated the achievement of remission according to SLE-DAS and DORIS definition. Secondly, we investigated the construct validity of SLE-DAS in comparison with SLEDAI-2k.

Methods We evaluated SLE patients treated with sc BLM from March 2019. Disease activity has been assessed by SLEDAI-2k, SLE-DAS and PGA (Physician Global Assessment) in all the established time-points [baseline (T0), after 1 (T1), 3 (T3), 6 (T6) and 12 (T12) months]. Furthermore, we applied and compared the achievement of remission according to SLE-DAS values (SLE-DAS ≤2.08 + PDN ≤5mg/daily) and DORIS definition (clinical SLEDAI-2k=0 + PGA<0.5 + antimalarials treatment, PDN≤5mg/daily, stable immunosuppressive treatment).

Results We enrolled 86 patients [M/F 5/81, median age 48 years (IQR 17.5), median disease duration 166 months (IQR 216)]. At baseline, median values of SLEDA-2k and SLE-DAS were 6 (IQR 4) and 5.77 (IQR 4.33), respectively, and they significantly correlated (r=0.719, CI 95% 0.586–0.815, p<0.0001; figure 1A). Median duration of treatment was 14 months (IQR 20). We found a significant reduction of SLEDAI-2k and SLE-DAS already at T1, maintained in the subsequent time-points (p<0.0001). At T12, a remission state was achieved by 60.4% of patients according to SLE-DAS definition and by 62.3% according to DORIS one (figure 1B). The two definitions of remission have demonstrated an agreement of 84%, with a Cohen’s kappa equal to 0.6.

• Download figure
• Open in new tab
• Download powerpoint

Abstract P60 Figure 1

(A) Correlation analysis by Spearman test between SLEDAI-2k and SLE-DAS at baseline (r=0.719, p<0.0001). (B) Stacked column chart for remission states according to SLE-DAS and DORIS definitions

Conclusions In this study we applied SLE-DAS to assess the efficacy of sc BLM, by analyzing its over-time changes and by comparing its performance with SLEDAI-2k. Indeed, our results suggest the usefulness of this new activity index in a real-life setting.