OBJECTIVES: Idiopathic multicentric Castleman disease (iMCD) is a rare disease characterised by the enlargement of lymph nodes throughout the body. The condition causes systemic inflammation and has a high symptom burden, impacting patients’ quality of life. No validated disease-specific patient-reported outcome measure (PROM) exists to quantify iMCD symptom burden and thereby monitor progression and evaluate treatment efficacy. The objective of this project is to develop a novel iMCD PROM via a collaborative approach in the UK, US, Canada, Australia, New Zealand, and Brazil.

METHODS: The project has four stages, with input from patient and multi-stakeholder advisory groups. In Stage 1, a review of existing literature and expert opinion was used to draft initial content. In Stage 2, draft content is being assessed in cognitive debriefing interviews with patients. In Stage 3, a revised PROM will be administered in an online patient survey to evaluate its psychometric performance and finalise its design. In Stage 4, the PROM will be re-administered to facilitate initial estimates of minimally clinically important difference, supplemented by qualitative interviews.

RESULTS: Forty-two items describing different possible symptoms were drafted, with two response scales that assess frequency and perceived impact on the respondent’s life. Based on patient and clinician advice, an initial recall period of the past week and 4-point response scales have been adopted. Cognitive debriefing interviews, involving patients from the UK and US, are ongoing. Quantitative survey work will involve participants internationally. Further progress, including challenges and successes in working with such a rare condition, will be outlined in November 2024.

CONCLUSIONS: This project is the first of its kind to produce a disease-specific PROM for assessing iMCD symptom burden through an international collaboration involving patients, clinicians, academics, and industry experts. The output will allow researchers, clinicians and allied stakeholders to quantify symptom burden over time and in response to interventions.