A patient-centred conceptual model of nocturnal scratch and its impact in atopic dermatitis: A mixed-methods study supporting the development of novel digital measurements.

Background: Emerging digital measures and clinical outcome assessments (COAs) leveraging digital health technologies (DHTs) could address the need for objective, quantitative measures of symptoms of atopic dermatitis (AD), such as nocturnal scratching. Development of such measures needs to be supported by evidence reflecting meaningfulness to patients. Objectives: To assess nocturnal scratching as a concept of interest associated with meaningful aspects of health of patients with AD (adults and children); and to explore patient-centred considerations for novel COAs measuring nocturnal scratch using DHTs. Methods: Phase 1 evaluated disease impacts on everyday life and the lived experience with nocturnal scratching through qualitative interviews of AD patients and caregivers. Phase 2 deployed a quantitative survey to a sample of AD patients as well as caregivers. Results: Four cohorts with various AD severity levels participated in Phase 1: (1) adults with AD (n = 15), (2) their caregivers/spouses/partners (n = 6), (3) children with AD (n = 14), and (4) their adult caregivers (n = 14). Findings were used to develop a conceptual model for nocturnal scratching as a potential concept of interest. The Phase 2 survey was completed by 1349 of 27640 invited adults with AD and caregivers of children with AD. The most burdensome aspects of AD reported were itchy skin and scratching. Overall, ∼65% of participants reported nocturnal scratching ≥1 day/week, resulting in ∼1-1.4 h of sleep lost per night. In all, 85%-91% of respondents considered it at least somewhat valuable that a treatment reduces night-time scratching. About 50% reported willingness to use technology to this end and ∼25% were unsure. Conclusion: Our results represented by the conceptual model confirm that nocturnal scratch is a concept of interest related to meaningful aspects of health for patients with AD and therefore is worth being captured as a distinct outcome for clinical and research purposes. DHTs are suitable tools presenting an important measurement opportunity to assess and evaluate occurrence, frequency, and other parameters of nocturnal scratching as a disease biomarker or COA of treatment efficacy.