Cross-cultural validity of the WHO-5 Well-Being Index and Euthymia Scale: A clinimetric analysis

The assessment of psychological well-being and euthymia represents an emerging issue in clinical psychology and psychiatry. Rating scales and indices such as the 5-item version of the World Health Organization Well-Being Index (WHO-5) and the Euthymia Scale (ES) were developed but insufficient attention has been devoted to the evaluation of their cross-cultural validity. This is the first study using Clinimetric Patient-Reported Outcome Measures (CLIPROM) criteria to assess cross-cultural validity and sensitivity of five different versions of the WHO-5 and ES.

A multicenter cross-sectional study involving a total of 3762 adult participants from different European (i.e., Italy, Poland, Denmark) and non-European (i.e., China, Japan) countries was conducted. Item Response Theory models (Mokken and Rasch analyses) were applied.

Mokken coefficients of scalability were found to range from 0.42 to 0.84. The majority of the versions of the WHO-5 fitted the Rasch model expectations. Paired t-tests revealed that the Italian and Danish WHO-5 versions were unidimensional. Person Separation Reliability indices showed that the Polish, Danish, and Japanese ES versions could reliably discriminate between subjects with different levels of euthymia.

A convenience sampling was used, thus limiting the generalizability of study findings. In addition, no measures of negative mental health were administered.

WHO-5 can be used in international studies for cross-cultural comparisons since it covers transcultural components of subjective well-being. Findings also suggest that the ES can be used as a cross-cultural screening tool since it entailed the clinimetric property of sensitivity.