The development and initial validation of self-report measures of ICD-11 depressive episode and generalized anxiety disorder: The International Depression Questionnaire (IDQ) and the International Anxiety Questionnaire (IAQ)

Shevlin, Mark; Hyland, Philip; Butter, Sarah; McBride, Orla; Hartman, Todd K.; Karatzias, Thanos; Bentall, Richard P.

Abstract

Background
The new International Classification of Diseases came into effect in 2022 (ICD-11; World Health Organization, 2022) and included updated descriptions and diagnostic rules for “Depressive Episode” and “Generalized Anxiety Disorder.” No self-report measures align with these disorders so this study reports the development and initial validation of the “International Depression Questionnaire” (IDQ) and “International Anxiety Questionnaire” (IAQ).

Methods
Items were developed that aligned to the ICD-11 descriptions and their performance was assessed using data from a community sample (N = 2058) that was representative of the United Kingdom adult population.

Results
Item response theory models indicated that the two scales were unidimensional, and the items performed well in terms of difficulty and discrimination. Estimates of internal reliability were high. Based on ICD-11 derived diagnostic algorithms, 7.4% met requirements for ICD-11 Depressive Episode and 7.1% for Generalized Anxiety Disorder.

Conclusions
The IDQ and the IAQ are short, easy to use, self-report measures aligned to the new and updated ICD-11 diagnostic descriptions. This study provides initial evidence that the scales produce scores that are reliable and valid.

Citation

Shevlin, M., Hyland, P., Butter, S., McBride, O., Hartman, T. K., Karatzias, T., & Bentall, R. P. (2023). The development and initial validation of self-report measures of ICD-11 depressive episode and generalized anxiety disorder: The International Depression Questionnaire (IDQ) and the International Anxiety Questionnaire (IAQ). Journal of Clinical Psychology, 79(3), 854-870. https://doi.org/10.1002/jclp.23446

• Journal Article Type: Article
• Acceptance Date: Sep 22, 2022
• Online Publication Date: Oct 10, 2022
• Publication Date: 2023-03
• Deposit Date: Sep 27, 2022
• Publicly Available Date: Feb 15, 2023
• Print ISSN: 0021-9762
• Electronic ISSN: 1097-4679
• Publisher: Wiley
• Peer Reviewed: Peer Reviewed
• Volume: 79
• Issue: 3
• Pages: 854-870
• DOI: https://doi.org/10.1002/jclp.23446
• Keywords: anxiety, depression
• Public URL: http://researchrepository.napier.ac.uk/Output/2924685