Investigator's Global Assessment of Atopic Dermatitis (IGA)

DESCRIPTION:
The Investigator's Global Assessment for atopic dermatitis (AD) scale is used to assess the overall disease severity in dermatologic studies. The IGA is an easy-to-perform, standardized global assessment for use in AD clinical trials. Historically, both static and dynamic IGA scales have been used, with scoring that has ranged from 4 to 7 points.^1,2

DISEASE STATES: 
Atopic dermatitis

VALIDATED USES: 
Treatment monitoring in clinical trials

ADMINISTRATION METHOD:
Physician, clinician, HCP representative

COMMONLY USED IN:
Clinical trials

DETAILED DESCRIPTION:
The IGA is a relatively easy-to-understand global clinical assessment of AD disease severity.¹ The FDA recommends that an IGA serve as the primary or co-primary endpoint in clinical trials for new AD therapies.^2,3 In recent years, an advisory group of 24 global dermatology experts on AD developed a validated IGA scale for AD (vIGA-AD), which consists of a 5-point scale. It has been approved by the FDA for use in assessing AD in clinical trials.³

The vIGA-AD 5-point scale ranges from 0 (clear) to 4 (severe AD). A decrease in score indicates an improvement in signs and symptoms. The clinical signs used in the scale are consistent with those rated as the most important by patients and providers, including erythema, lichenification, induration/papulation, and oozing/crusting. Excoriation is an important component of AD but may vary significantly due to a variety of factors. The presence or severity of excoriation does not necessarily reflect disease severity and was excluded from the morphologic descriptors of the vIGA-AD.³

• In clinical trials, typically the primary/co-primary efficacy IGA endpoint is based on a proportion of subjects achieving an IGA score of 0 or 1

vIGA-AD RATING SCALE³

Note: In indeterminate cases, please use extent to differentiate between scores. For example: Patient with marked erythema (deep or bright red), marked papulation, and/or marked lichenification that is limited in extent will be considered “3 - Moderate”.

VALIDITY:
Simpson et al. 2020 demonstrated that the 5-point vIGA-AD scale had strong interrater reliability and excellent agreement based on intraclass correlation (ICC) metrics, Kendall’s coefficient of concordance W (Kendall’s W) and weighted kappa (quadratic); interrater reliability (0.849; Kendall’s W) and agreement (0.869; weighted kappa).³

LIMITATIONS:
The vIGA-AD study consisted of web-based surveys where ratings were assessed from photographs, which limit the raters’ ability to fully assess the physical characteristics as compared to a physical examination. In addition, assessments were often restricted to 1 body region.³

This resource is intended for educational purposes only and is intended for US healthcare professionals. Healthcare professionals should use independent medical judgment. All decisions regarding patient care must be handled by a healthcare professional and be made based on the unique needs of each patient.

References: 1. Eichenfield LF, Tom WL, Chamlin SL, et al. Guidelines of care for the management of atopic dermatitis: section 1. Diagnosis and assessment of atopic dermatitis. J Am Acad Dermatol. 2014;70(2):338-351. doi:10.1016/j.jaad.2013.10.010 2. Futamura M, Leshem YA, Thomas KS, Nankervis H, Williams HC, Simpson EL. A systematic review of Investigator Global Assessment (IGA) in atopic dermatitis (AD) trials: many options, no standards. J Am Acad Dermatol. 2016;74(2):288-294. doi:10.1016/j.jaad.2015.09.062 3. Simpson E, Bissonnette R, Eichenfield LF, et al. The Validated Investigator Global Assessment for Atopic Dermatitis (vIGA-AD): the development and reliability testing of a novel clinical outcome measurement instrument for the severity of atopic dermatitis. J Am Acad Dermatol. 2020;83(3):839-846. doi:10.1016/j.jaad.2020.04.104