D3.413 - Development of the Mastocytosis Symptom Severity Daily Diary (MS2D2) for Non-Advanced Systemic Mastocytosis (NonAdvSM) Patients and Establishing Content Validity

The aim of this study was to develop a patient reported outcome daily diary, the Mastocytosis Symptom Severity Daily Diary (MS2D2), that is fit for purpose to measure the signs and symptoms of patients with Non-Advanced Systemic Mastocytosis (NonAdvSM) while on treatment.

A qualitative study utilizing hybrid concept elicitation and cognitive debriefing interviews was conducted among 18 patients in the United States (n=17) and Canada (n=1) with a physician-confirmed diagnosis of NonAdvSM. Interviews elicited signs, symptoms, and health-related quality of life impacts of NonAdvSM directly from patients to further inform a preliminary conceptual model based on concepts derived from a targeted literature review and clinician interviews. Based on the preliminary conceptual model, draft items of the MS2D2 were developed and debriefed with patients. Interviews captured feedback from patients on the clarity and relevance of the instructions, items, and response scales of the MS2D2. There was refinement of the instrument based upon patient feedback.

Patients reported a diverse range of symptoms and impacts, with over 50% experiencing concepts in domains related to dermatology, neurocognition, gastrointestinal, pain, fatigue, and emotional impacts. The most commonly reported symptoms were skin redness (n=18), flushing (n=18), fatigue (n=17), itch (n=17), spots (n=17), diarrhea (n=17), difficulty concentrating (n=17), and brain fog (n=17). Overall, interviews supported the selection of concepts included in the draft MS2D2. Cognitive debriefing of the MS2D2 led to iterative revisions of the instrument, with patient insights prompting the removal or clarification of some items, as well as adjustments to the rating scale to enhance understandability. The final MS2D2 includes instructions, items, and response scales that are both relevant and comprehensible to patients.

Content validity of the MS2D2 is supported by findings from interviews with patients suffering from NonAdvSM, which confirmed the relevance of the signs/symptoms captured within the instrument and that the items and response options are clear and well-understood.