The validated Investigator Global Assessment for Atopic Dermatitis (vIGA-AD) is a static, 5-point clinician-reported measure of overall atopic dermatitis severity, graded 0 (clear), 1 (almost clear), 2 (mild), 3 (moderate), or 4 (severe). It was developed by Eli Lilly and Company with atopic dermatitis experts and advisors of the International Eczema Council (IEC) in response to the wide variability of global assessments used in earlier trials, documented by Futamura et al. (2016), and with input from the US Food and Drug Administration on the final morphological descriptors.

The assessor selects the grade whose morphological description best matches the overall appearance of the lesions at the time of assessment. Each grade is anchored by descriptors for erythema, induration or papulation, lichenification, and oozing or crusting, and not every characteristic listed under a grade needs to be present. In indeterminate cases, the extent of disease is used to differentiate between grades, so that marked but limited disease is scored as moderate. Excoriations are not considered when assessing severity.

Reliability testing by Simpson et al. (2020) demonstrated substantial inter-rater and intra-rater agreement among trained dermatologists, and the scale is supported by an investigator training and certification module. By 2020 the vIGA-AD had been adopted by 13 sponsors in 38 clinical trials, and it has since become the standard global endpoint in atopic dermatitis registration programmes. The Harmonising Outcome Measures for Eczema clinical practice initiative (HOME-CP) has recommended the vIGA-AD, alongside the EASI and body surface area, for measuring clinical signs in routine care.

Treatment success in clinical trials is conventionally defined as a vIGA-AD score of 0 or 1 (clear or almost clear) together with an improvement of at least 2 points from baseline; a 1-point reduction has been proposed as the threshold for a clinically meaningful change.

Because a global grade does not quantify extent, the product of the vIGA-AD and the percentage of body surface area involved (vIGA-AD x BSA, range 0 to 400) has been validated as a practice-friendly composite. Suh et al. (2020) showed in children that it correlates more closely with the EASI than the grade alone (r = 0.92 versus 0.76), Silverberg et al. (2021) confirmed its validity, reliability, and responsiveness in adults and children and derived interpretability thresholds of 2.5 (mild), 31.5 (moderate), and 118.5 (severe) against physician-rated global severity, and Paller et al. (2022) found 88 to 94 percent concordance between IGA x BSA-50, -75, and -90 responses and the corresponding EASI responses in pooled dupilumab trial data. The composite is one of the sign instruments adopted by the HOME-CP consensus for routine care. One patient palm, including the fingers, corresponds to approximately 1% of total body surface area.

The scale text is copyright 2017 Eli Lilly and Company and is distributed under a Creative Commons Attribution-NoDerivatives 4.0 International License, which permits reproduction with attribution but not modification; the IEC recommends that no modifications are made to the scale so that assessments remain harmonised across settings. vIGA-AD is a trademark of Eli Lilly and Company. This calculator reproduces the scale without alteration and is not affiliated with, sponsored by, or endorsed by Eli Lilly and Company or the International Eczema Council.