Measurement properties of the Patient-Reported Outcomes Measurement Information System Itch Questionnaire item banks in adults with atopic dermatitis

Abstract

Background: The Patient-Reported Outcomes Measurement Information System (PROMIS) Itch Questionnaire (PIQ) was recently developed.

Objective: To validate PIQ short forms in adults with AD.

Methods: Self-administered questionnaires and skin examinations were performed in 239 adults with atopic dermatitis (AD) in a dermatology practice setting.

Results: PIQ items had good content validity. PIQ item bank T-scores strongly correlated with each other, moderately correlated with numeric and verbal rating scales for worst or average itch and with itch frequency, moderately to strongly correlated with patient-oriented eczema measure, and weakly to moderately correlated with the Eczema Area and Severity Index and Objective-Scoring AD (Spearman correlations, P < .0001). There were significant and stepwise increases of T-scores for all item banks with increasing patient-reported global severity (Wilcoxon rank sum test, P < .0001). However, there was limited ability to discriminate between the lowest or highest 2 levels of AD or itch severity. Item banks showed good internal consistency (Cronbach α, 0.91-0.95). No differential item functioning was identified by age, sex, race/ethnicity, or educational level. There were floor effects for total scores, particularly in almost clear/mild AD or itch.

Limitations: Single-center study.

Conclusions: PIQ item bank short forms showed good content and construct validity and are feasible for potential use in clinical trials and practice.

Keywords: atopic dermatitis; burden; eczema; itch; patient-reported outcomes; pruritus; quality of life; severity.