Nisha Suyien Chandran

Background Several registries for hidradenitis suppurativa (HS) already exist in Europe and the USA. There is currently no global consensus on a core dataset (CDS) for these registries. Creating a global HS registry is challenging, owing to logistical and regulatory constraints, which could limit opportunities for global collaboration as a result of differences in the dataset collected. The solution is to encourage all HS registries to collect the same CDS of information, allowing registries to collaborate. Objectives To establish a core set of items to be collected by all HS registries globally. The core set will cover demographic details, comorbidities, clinical examination findings, patient-reported outcome measures and treatments. Methods Beginning in September 2022, 20 participants – including both clinicians with expertise in HS and patient advocates – from eight countries across three continents participated in a Delphi process consisting of four rounds of voting, with all participants completing each round. A list of potential items for inclusion in the core set was generated from the relevant published literature, including systematic reviews of comorbidities in HS, clinical and examination findings, and epidemiology. For disease severity and progression items, the Hidradenitis SuppuraTiva Core outcome set International Collaboration (HiSTORIC) core set and other relevant instruments were considered for inclusion. This resulted in 47 initial items. Participants were invited to suggest additional items to include during the first round. Anonymous feedback was provided to inform each subsequent round of voting to encourage consensus. Results The eDelphi process established a CDS of 48 items recommended for inclusion in all HS registries globally. Conclusions The routine adoption of this CDS in current and future HS registries should allow registries in different parts of the world to collaborate, enabling research requiring large numbers of participants.