The WHO-5 well-being index – validation based on item response theory and the analysis of measurement invariance across 35 countries

• Published in: Journal of affective disorders reports Vol. 1; p. 100020
• Main Authors: Sischka, Philipp E., Costa, Andreia P., Steffgen, Georges, Schmidt, Alexander F.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.2020; Elsevier
• Subjects: Cross-cultural research; Depression; Differential item functioning; Item response theory; Measurement invariance; Psychiatric/Mental Health; Short scale; Well-being; WHO-5; Cross-cultural research; Differential item functioning; Well-being; Item response theory; Short scale; Depression; Measurement invariance; WHO-5
• ISSN: 2666-9153; 2666-9153
• DOI: 10.1016/j.jadr.2020.100020

•The WHO-5 is a psychometrically sound brief measure with non-invasive questions that tap into the subjective well-being of respondents.•The reliability of the WHO-5 is satisfactory for all countries in general and at important cutoffs.•The graded response model for the WHO-5 fitted the data best for all countries.•The WHO-5 showed some non-invariant parameters across countries.•Large-scale cross-cultural studies that use the WHO-5 should employ a latent variable modeling approach that accounts for non-invariant parameter across countries. The five-item World Health Organization Well-Being Index (WHO-5) is a frequently used brief standard measure in large-scale cross-cultural clinical studies. Despite its frequent use, some psychometric questions remain that concern the choice of an adequate item response theory (IRT) model, the evaluation of reliability at important cutoff points, and most importantly the assessment of measurement invariance across countries. Data from the 6th European Working Condition survey (2015) were used that collected nationally representative samples of employed and self-employed individuals (N = 43,469) via computer-aided personal interviews across 35 European countries. An in-depth IRT analysis was conducted for each country, testing different IRT assumptions (e.g., unidimensionality), comparing different IRT-models, and calculating reliabilities. Furthermore, measurement invariance analysis was conducted with the recently proposed alignment procedure. The graded response model fitted the data best for all countries. Furthermore, IRT assumptions were mostly fulfilled. The WHO-5 showed overall and at critical points high reliability. Measurement invariance analysis revealed metric invariance but discarded scalar invariance across countries. Analysis of the test characteristic curves of the aligned graded response model indicated low levels of differential test functioning at medium levels of the WHO-5, but differential test functioning increased at more extreme levels. The current study has no external criterion (e.g., structured clinical interviews) to assess sensitivity and specificity of the WHO-5 as a depression screening-tool. The WHO-5 is a psychometrically sound measure. However, large-scale cross-cultural studies should employ a latent variable modeling approach that accounts for non-invariant parameters across countries (e.g., alignment).