Minimum Data Set for Treatment Effectiveness in Pyoderma Gangrenosum for an International Registry: An International Multidisciplinary eDelphi Consensus

Background: Pyoderma gangrenosum (PG) is a rare, painful neutrophilic dermatosis with a profound impact on patient quality of life. Its management is hindered by a lack of approved therapies, limited clinical trials, and low-quality evidence. The rarity of the disease and funding constraints have impeded research progress and the development of standardized outcome measures. Patient data registries offer a promising solution to these challenges, providing essential infrastructure to improve evidence generation and clinical care. Objective: To develop a consensus-based minimum data set for an international treatment effectiveness registry for pyoderma gangrenosum, informed by real-world clinical data. Methods: An initial list of candidate domain items was generated based on a systematic literature review following a previously published protocol. An international, multi-stakeholder panel of 45 participants-including patients with PG, clinicians, researchers, methodologists, and industry representatives-was convened from 97 invited experts. Through three rounds of modified Delphi surveys and a virtual consensus meeting, items were ranked using predefined criteria: "consensus in" (≥70% scoring 7-9 and ≤15% scoring 1-3), "consensus out" (≥70% scoring 1-3 and ≤15% scoring 7-9), and "no consensus." A final verification survey confirmed inclusion if <30% of participants voted "no." Results: All 45 stakeholders completed all three Delphi rounds (0% dropout). Thirty-four (76%) participated in the consensus meeting, and 42 (93%) completed the final verification survey. Of 143 initial items across 24 domains, 118 items across 26 domains achieved consensus for inclusion in the minimum data set. Conclusions: This international consensus establishes a standardized framework for collecting real-world data on PG. The resulting registry will serve as a critical resource for evaluating treatment effectiveness, understanding disease progression, and improving patient outcomes. It will also support future clinical trials, guideline development, quality improvement initiatives, and global patient recruitment efforts.