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 Sep;83(3):839-846. doi: 10.1016/j.jaad.2020.04.104. Epub 2020 Apr 25.


Background: An Investigator Global Assessment (IGA) is recommended by health agencies for drug registration in atopic dermatitis (AD). Current IGA scales lack standardization.

Objectives: To develop an IGA scale, training module, and clinical certification examination for use in AD trials; establish content validity; and assess reliability.

Methods: Expert dermatologists participated in the development of the validated IGA for AD (vIGA-ADTM). Reliability (interrater and intrarater) was assessed by 2 web-based surveys. Clinical certification for investigators consisted of a training module and examination.

Results: Expert consensus was achieved around a 5-point IGA scale including morphologic descriptions, and content validity was established. Survey 1 showed strong interrater reliability (Kendall's coefficient of concordance W [Kendall's W], 0.809; intraclass correlation [ICC], 0.817) and excellent agreement (weighted kappa, 0.857). Survey 2, completed 5 months after training of dermatologists, showed improvements in scale reliability (Kendall's W, 0.819; ICC, 0.852; weighted kappa, 0.889). In this study, 627 investigators completed vIGA-AD training and certification.

Limitations: Ratings were assessed on photographs.

Conclusion: A validated IGA scale and training module were developed with the intent of harmonizing assessment of disease severity in AD trials. Strong reliability and excellent agreement between assessments were observed.

Keywords: Investigator Global Assessment; atopic dermatitis; atopic eczema; clinical outcome measure; severity; validated.

Publication types

  • Validation Study

MeSH terms

  • Adult
  • Child
  • Consensus Development Conferences as Topic
  • Consensus*
  • Dermatitis, Atopic / diagnosis*
  • Dermatitis, Atopic / therapy
  • Dermatologists / standards
  • Dermatologists / statistics & numerical data
  • Humans
  • Observer Variation
  • Outcome Assessment, Health Care / standards*
  • Photography
  • Reproducibility of Results
  • Severity of Illness Index*
  • Skin / diagnostic imaging
  • Surveys and Questionnaires / statistics & numerical data
  • Telecommunications