The Validated Investigator Global Assessment for Atopic Dermatitis (vIGA‐AD™): a clinical outcome measure for the severity of atopic dermatitis

BACKGROUND: The validated Investigator Global Assessment for Atopic Dermatitis (vIGA‐AD™) is a standardized severity assessment for use in clinical trials and registries for atopic dermatitis (AD). OBJECTIVES: To investigate the reliability, validity, responsiveness and within‐patient meaningful change of the vIGA‐AD. METHODS: Data were analysed from adult patients with moderate‐to‐severe AD in the BREEZE‐AD1 (N = 624 patients; NCT03334396), BREEZE‐AD2 (N = 615; NCT03334422) and BREEZE‐AD5 (N = 440; NCT03435081) phase III baricitinib clinical studies. RESULTS: Across studies, test–retest reliability for stable patients showed moderate‐to‐good agreement [range of Kappa values for Patient Global Impression of Severity–Atopic Dermatitis (PGI‐S‐AD), 0·516–0·639; for Eczema Area and Severity Index (EASI), 0·658–0·778]. Moderate‐to‐large correlations between vIGA‐AD and EASI or body surface area (range at baseline, 0·497–0·736; Week 16, 0·716–0·893) supported convergent validity. Known‐groups validity was demonstrated vs. EASI and PGI‐S‐AD (vIGA‐AD for severe vs. moderate EASI categories at baseline, P < 0·001). Responsiveness was demonstrated vs. EASI (P < 0·001 for much improved vs. improved and improved vs. stable). Anchor‐ and distribution‐based methods supported a vIGA‐AD change of –1·0 as clinically meaningful. These findings are limited to populations defined by the studies’ inclusion and exclusion criteria. CONCLUSIONS: The vIGA‐AD demonstrated sufficient reliability, validity, responsiveness and interpretation standards for use in clinical trials. What is already known about this topic? A description of the development of the validated Investigator Global Assessment for Atopic Dermatitis (vIGA‐AD™) has been published previously. What does this study add? The current study validates the vIGA‐AD by demonstrating appropriate test–retest reliability, convergent validity, known‐groups validity and responsiveness across three baricitinib clinical studies. In addition, a 1‐point change was identified as a clinically meaningful patient‐perceived change minimal clinically important difference in the vIGA‐AD. What are the clinical implications of the work? The vIGA‐AD is a measure for investigator assessment of atopic dermatitis suitable for use in clinical research.