Comparative Study of Two Classification Criteria Sets in Real Clinical Practice for Behçet's Disease

Background: Behçet's Disease (BD) was traditionally classified according to the International Study Group (ISG), where oral ulcers were mandatory. The International Team for the Revision of the International Criteria for BD (ICBD) introduced a scoring system instead. Our aim was to assess (a) sensitivity, (b) concordance between ISG and ICDB criteria in global and severe BD cases (ocular, vascular, and neurological), and (c) evaluate their clinical implications. Methods: Retrospective cohort study including 142 BD patients diagnosed in a well-defined population in Northern Spain, between January 1980 and November 2023. Both ISG and ICBD criteria were compared, sensitivity and concordance were assessed using Prevalence-Adjusted and Bias-Adjusted Kappa (PABAK) and the unadjusted Kappa. Results: A total of 142 BD patients diagnosed by expert rheumatologists (73 men; mean age of 36.4) were studied. Among them, 84 met ISG criteria, while 116 fulfilled ICBD criteria. Sensitivity of ISG and ICBD criteria in the overall cohort was (59.1% and 81.6%), respectively. Among patients with severe manifestations (ocular, vascular, or neurological), sensitivity increased to 71.2% for ISG and 92.5% for ICBD. Overall concordance was moderate (Kappa = 0.490), with 70.4% of patients classified identically. When adjusting prevalence and bias, concordance improved slightly (PABAK = 0.549). Of the 32 patients classified as BD exclusively by ICBD, 7 were receiving anti-TNF therapy, and 2 were receiving apremilast. Conclusions: The ICBD criteria demonstrated higher sensitivity than the traditional ISG criteria in classifying BD, particularly in severe cases. Classifying these additional patients under ICBD facilitated the initiation of on-label biologic treatments, potentially enhancing BD management, especially for severe cases.