Background: Structured patient-reported outcomes of atopic dermatitis (AD) severity are not standardized in clinical practice. Objectives: To determine the construct validity, internal consistency, cross-cultural validity and floor or ceiling effects of multiple AD severity assessments. Methods: This is a cross-sectional, population-based study of 2893 adults, including 602 adults who met a modified set of U.K. diagnostic criteria for AD. AD severity was assessed using self-reported global AD severity, Patient-Oriented Eczema Measure (POEM), Patient-Oriented Scoring Atopic Dermatitis (PO-SCORAD) and its objective and subjective components, and numerical rating scale (NRS)-itch. Quality of life was assessed using Short-Form (SF)-12 mental and physical health scores, Short-Form Six Dimensions (SF-6D) health utility scores and Dermatology Life Quality Index (DLQI). Mental health was assessed with the Hospital Anxiety and Depression Scale (HADS). Results: PO-SCORAD, PO-SCORAD objective and subjective subscores, NRS-itch and POEM all had moderate-to-strong correlations with each other and DLQI, fair-to-moderate correlations with HADS-anxiety and HADS-depression, and inverse correlations with SF-12 mental component score and SF-6D (Pearson correlations, P < 0·001). All scores showed good criterion validity as judged by anova and receiver operator characteristics. PO-SCORAD, PO-SCORAD objective subscore and POEM had similarly good internal consistency (Cronbach's alpha = 0·84, 0·82 and 0·86); the PO-SCORAD subjective subscore was less internally consistent (alpha = 0·57). All scores showed potentially poor cross-cultural validity as demonstrated by uniform and nonuniform differential item functioning by age, sex and/or race/ethnicity for multiple items. There were floor effects for POEM, but not for the other assessments. Conclusions: PO-SCORAD, PO-SCORAD objective and subjective subscores, NRS-itch and POEM appear to be valid for assessing AD severity in clinical practice. What's already known about this topic?. Few studies have demonstrated the validity of the atopic dermatitis severity assessments Patient-Oriented Scoring Atopic Dermatitis (PO-SCORAD), PO-SCORAD subscores, numerical rating scale (NRS)-itch and Patient-Oriented Eczema Measure (POEM). What does this study add?. This study demonstrates that PO-SCORAD, PO-SCORAD subscores, NRS-itch and POEM all had good construct validity in the assessment of atopic dermatitis severity in adults. Only POEM demonstrated floor effects. What are the clinical implications of this work?. PO-SCORAD, PO-SCORAD subscores, NRS-itch and POEM all appear to have sufficient validity to be used as assessments of atopic dermatitis severity in clinical practice.
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