There is a great need for widely‐accepted outcome measures for randomized clinical trials in Behçet syndrome (BS). The Outcome Measures in Rheumatology Clinical Trials (OMERACT) BS Working Group, a large, multi‐disciplinary group of experts in BS and patients with BS, worked to develop a data-driven Core Set outcome measures for use in all clinical trials of BS.

The Core Domain Set was developed through a multi‐stage, comprehensive, iterative project which included a systematic review. A Delphi exercise involving both physician‐experts and patients in BS, and feedback, insight, generated, and utilization of the data  by these processes to develop a final Core Domain Set. Since trials in BS often focus on specific manifestations and not the disease in its entirety, the final proposed Core Set includes five domains mandatory for study in all trials in BS (disease activity, new organ involvement, quality of life, adverse events, and death) with additional sub‐domains mandatory for the study of specific organ systems.

In conclusion, the Core Set of Domains in BS provides the foundation through which the international research community, including clinical investigators, patients, biopharmaceutical industry, and government regulatory bodies, can harmonize the study of this complex disease, compare findings across studies, and advance the development of effective therapies.