Background/Purpose: Most current Behçet’s disease (BD) activity assessment tools are strongly based on patient-reported symptoms and findings allowing a wide range of observer-dependent interpretations and do not always differentially weigh organ-threatening vs non-organ-threatening disease activity or degrees of remission depth. Here we aimed to develop and test a BD-specific disease activity instrument that is focused to a high extent on objective findings, dissects the impact of organ-threatening from non-organ-threatening disease, and classifies remission depth.

Methods: We generated an instrument that requires the verification of reported symptoms through findings on physical exam and diagnostic studies and incorporates results of screening and follow-up studies in four minor system categories, including “mucosal”, “cutaneous”, “cutaneous pathergy”, “articular”, and four major system categories, including “ocular”, “vascular”, “CNS”, “GI“. Evidence of one or more phenotypically eligible findings in any category triggered scoring with major categories receiving a 3-fold weighed score over minor ones. EBDA and Behçet’s Disease Current Activity Form (BDCAF, the current standard) scoring was applied to 59 BD patient encounters comprising a wide range of degrees of BD severity and prototypical manifestations. Scores were analyzed using Pearson’s, Spearman’s, Kendall’s correlation coefficients, and Lin’s concordance correction.

Results: There was moderate positive correlation between EBDA and BDCAF across all scores (Pearson’s 0.5817, p< 0.0001; Kendall’s 0.5568, Spearman’s 0.6328, p< 0.000001) without a linear relationship (Lin’s 0.1019, 99.9% confidence). On analysis of categorized scores for lower (EBDA < 12, which excludes major organ involvement) vs higher activity (EBDA ≥ 12, which includes major organ involvement) there was evidence for moderate positive correlation with BDCAF for lower (Kendall’s 0.4123, p< 0.001; Spearman’s 0.4031, p< 0.01), but not for higher activity scores (Kendall’s 0.2965, p=0.2546; Spearman’s 0.3045, p=0.2698). BDCAF appeared to underestimate organ-threatening (mostly ocular and major vascular) disease in >70% and missed it completely in 13% of cases.

Conclusion: EBDA is a new instrument for the finding-based assessment of BD activity which may exhibit improved performance in moderate-severe and severe, potentially organ-threatening BD. In addition, the instrument allows estimates of disease remission depth. Given its strong focus on objectively verifiable findings directly relevant to the time point of assessment, EBDA may be especially suitable in research-intense settings such as for the classification of study subjects for analysis of presumably disease activity-dependent molecular or cellular responses and immune phenotypes.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/evidence-based-behcets-disease-activity-scale-ebda-a-new-instrument-with-improved-acuity-for-major-organ-disease-activity-and-remission-depth-assessment/