Sleep-loss related to itch in atopic dermatitis: assessing content validity and psychometric properties of a patient-reported sleep-loss rating scale.

BACKGROUND: Sleep loss is a key factor contributing to disease burden in people with atopic dermatitis (AD). Mitigating itch to improve sleep is an important outcome of AD treatment. This study explored the content validity and measurement properties of the Sleep-Loss Scale, a single-item rating scale for assessing itch interference with sleep in clinical trials of AD treatments. METHODS: Concept elicitation and cognitive debriefing interviews were conducted with 21 adults and adolescents (12-17 years of age) with moderate-to-severe AD to develop a conceptual model of patient experience in AD and explore the content validity of the scale. Data collected from adults with moderate-to-severe AD enrolled in a phase 2b study (NCT03443024) were used to assess Sleep-Loss Scale's psychometric performance, including reliability, construct validity, and ability to detect change. Meaningful within-patient change (MWPC) thresholds were also determined using anchor-based methods. RESULTS: Qualitative findings from concept elicitation highlighted the importance of sleep-loss related to itch in AD. Debriefing analysis of the Sleep-Loss Scale indicated that the scale was relevant, appropriate, and interpreted as intended. Trial data supported good reliability, construct validity and ability to detect improvement. MWPC was defined as a 1-point improvement using trial data, a finding supported by qualitative data. CONCLUSIONS: The Sleep-Loss Scale provides a valid and reliable patient-reported measure of the impact of itch on sleep in patients with AD, and can detect change, indicating it is fit-for-purpose to evaluate the efficacy of AD treatments in moderate-to-severe patients.

Assessing Itch Severity: Content Validity and Psychometric Properties of a Patient-Reported Pruritus Numeric Rating Scale in Atopic Dermatitis.

BACKGROUND: Pruritus, or itch, is a key symptom of atopic dermatitis (AD); as such, mitigating itch is an important outcome of AD treatment. This study explored the content validity and measurement properties of the Pruritus Numeric Rating Scale (Pruritus NRS), a novel single-item scale for assessing itch severity in clinical trials of AD treatments. METHODS: In this mixed-methods study, qualitative interviews were conducted with 21 people with moderate-to-severe AD (n = 15 adult, n = 6 adolescent) to develop a conceptual model of the patient experience in AD and explore the content validity of the Pruritus NRS. Data collected daily from adults with moderate-to-severe AD enrolled in a phase 2b study (NCT03443024) were used to assess the Pruritus NRS' psychometric performance, including reliability, construct validity, and responsiveness. Meaningful within-patient change (MWPC) thresholds were also determined using anchor-based methods. RESULTS: Qualitative findings highlighted the importance of itch in AD, including severity, persistence, frequency, and daily life interference. Patient debriefing of the Pruritus NRS indicated that the scale was relevant, appropriate, and interpreted as intended. Trial data supported overall good psychometric properties. MWPC was defined as a 3-point improvement in Pruritus NRS score, a finding supported by qualitative data. CONCLUSIONS: The Pruritus NRS provides a valid and reliable patient-reported measure of itching severity in patients with moderate-to-severe AD, and can detect change, indicating it is fit-for-purpose to evaluate the efficacy of AD treatments in this population. TRIAL REGISTRATION: ClinicalTrials.gov identifier, NCT03443024.