BACKGROUND: Hand eczema (HE) is a common and complex skin disease. A uniform set of core outcomes and related measures for use in clinical trials is lacking, making it difficult to compare results across HE studies.

OBJECTIVE: To reach consensus on a set of core domains and subdomains that should be measured in future therapeutic HE trials.

METHODS: In 2024, we conducted a two-round online Delphi (eDelphi) survey among international HE experts, including physicians, patients and their relatives, researchers and industry representatives. A domain/subdomain was included in the core set when ≥80% of participants rated is as 'critically important'; 50% agreement or less resulted in its exclusion. Results from 50% to 80% were deemed controversial and subject for further discussion. During a hybrid consensus meeting, the stakeholders reviewed, completed and, if necessary, revised the preliminary eDelphi consensus.

RESULTS: In the first and second round of the eDelphi, 208 and 134 persons, respectively, participated. Forty participants from 18 countries attended the consensus meeting. Consensus was reached to include the core domains 'signs of HE' (with five core subdomains), 'symptoms of HE' (two subdomains), 'HE-related quality of life' (four subdomains) and 'HE control over time' (four subdomains). The subdomains 'desquamation/scaling' and 'emotional impact/mental health' remained controversial. Consensus was reached that the domains 'skin barrier function' and 'patient-reported treatment experience' and 28 subdomains should not be part of the core outcome set.

CONCLUSIONS: To produce comparable and meaningful results, future trials evaluating the effectiveness of HE treatments should measure signs and symptoms of HE, HE-related quality of life and HE control over time as core outcome domains. The next step of the HE core outcome set initiative (HECOS) is to identify appropriate measurement instruments.