PT7:02 Discordance between SLEDAI-2K and BILAG-2004 disease activity classification leads to divergent treatment decisions under EULAR 2023 recommendations: a post-hoc analysis of anifrolumab trials

Objectives The 2023 EULAR recommendations for the management of SLE endorse stratifying disease activity into mild, moderate, and severe categories to guide treat-to-target (T2T) strategies. Both SLEDAI and BILAG are suggested for this purpose, but their limitations may affect treatment guidance. We aimed to compare disease activity classification based on SLEDAI-2K and BILAG-2004.Methods This post-hoc analysis included the aggregated placebo arms from phase 2 and 3 anifrolumab trials (MUSE, TULIP-1, TULIP-2) in moderate-to-severe SLE. Physicians’ assessments (clinical and laboratory data, BILAG-2004, CLASI-A, SLEDAI-2K, and Physician Global Assessment [PhGA]) and patient-reported outcomes (PROs: LupusQoL, EQ-5D, FACIT-F, and Patient Global Assessment [PtGA]) were analyzed at week 12. The SLE-DAS was retrospectively scored. Disease activity was categorized as mild, moderate, or severe according to SLEDAI-2K (12) and BILAG-2004 (=2B, >=1A domains). Agreement between classifications was assessed with Cohen’s Kappa. Proportions of patients per category were compared using McNemar’s test. Differences in lupus features, disease activity, and PROs between patients classified only by SLEDAI-2K, only by BILAG-2004, or by both indices were evaluated with Kruskal-Wallis, Chi-squared, or Fisher’s exact tests.Results At week 12, disease activity classification differed substantially between indices ( figure 1). By SLEDAI-2K, 36.1% of patients were mild, 49.1% moderate, and 14.8% severe, whereas BILAG-2004 classified 56.2%, 22.4%, and 21.5%, respectively. The proportion of patients across mild and moderate categories differed significantly between tools (p