Background: Multiple strategies have been used to evaluate the minimal important change (MIC) of the Eczema Area and Severity Index (EASI) and Scoring Atopic Dermatitis (SCORAD). The meaningfulness of these MICs is not well established across all severities of atopic dermatitis (AD). Objectives: To determine the MIC of percentage and absolute improvement of EASI and SCORAD scores in adults and children with AD. Methods: We performed a prospective dermatology practice-based study using questionnaires and evaluation by a dermatologist (n = 826). An anchor-based approach was used to determine thresholds for the percentage and absolute MICs of EASI, SCORAD and objective SCORAD (O-SCORAD) at follow-up from baseline. Results: One-grade improvements of Physician’s Global Assessment (PGA) and validated Investigator Global Assessment scale for AD (vIGA-AD) were associated with 50%, 35% and 35% decreases of EASI, SCORAD and O-SCORAD, respectively. The thresholds for percentage MIC of EASI (Kruskal–Wallis test, P = 0·61), SCORAD (P = 0·07) and O-SCORAD (P = 0·09) were similar across baseline AD severities. One-grade improvements of PGA and vIGA-AD were associated with 14·0- and 14·9-point decreases of EASI, 19·9- and 14·9-point decreases of SCORAD, and 15·5- and 17·4-point decreases of O-SCORAD. The thresholds for the absolute MIC of EASI (P < 0·001), SCORAD (P < 0·001) and O-SCORAD (P < 0·001) significantly differed by baseline AD severity. Percentage and absolute MICs for EASI and SCORAD were associated with improvements of AD symptoms and quality of life. Conclusions: EASI 50, SCORAD 35 and O-SCORAD 35 were meaningful percentage MICs regardless of baseline AD severity. The absolute MICs for EASI, SCORAD and O-SCORAD varied by baseline AD severity.
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