Producing a Novel Symptom Burden Scale for People Living With Idiopathic Multicentric Castleman Disease (ISBUS)

"Stage 1: Secondary analysis of a previous international survey to identify items~Stage 2: Cognitive debriefing interviews with about 10 people living with iMCD to assess the content validity of the items~Stage 3: Completion of questionnaire to finalise scale~Stage 4a: Re-administering of follow-up questionnaire to Stage 3 patients to assess minimally important clinical difference. Test-retest will be calculated only in patients exhibiting no change.~Stage 4b: Qualitative interviews with a subset of participants from Stages and 4 to help with interpretation of meaningful difference from their perspective"