[Validation of the German-language version of the Injustice Experience Questionnaire (IEQ) in five outpatient...

Occupational and social rehabilitation can be influenced by perceived injustice that results from pain. Currently, the Injustice Experience Questionnaire (IEQ), the tool most commonly used to assess perceived injustice, is not available in German. The aim of this study was the validation of the German-language version of the IEQ.

The validation of the IEQ was carried out via a web-based survey. For this purpose, participants completed the IEQ and construct-related scales analogous to the original study Tampa Scale of Kinesiophobia (TSK), Depression scale of the Depression Anxiety and Stress Scales (D-DASS), Pain Disability Index (PDI), and McGill Pain Questionnaire (MPQ). In addition, the participants completed questions on their socioeconomic status and on the cause of their pain, taken from the German Pain Questionnaire.

Of 223 respondents, 134 (60.1%) returned a completed questionnaire and were included in the study. In all, 26.1% of participants reported suffering from pain resulting from accidents. None of the reviewed one- to three-factor solutions for the IEQ's structure achieved a good model fit. The best results were found for a two-factor solution, whereby the exploratory factor analysis revealed almost all items loaded highly on both factors and the confirmatory factor analysis showed high correlations between the factors. These findings are consistent with previous studies. The IEQ correlated highly and significantly with the other psychological instruments. There were no floor or ceiling effects. Cronbach's α for the German IEQ version was 0.93 and thus attests a high level of internal consistency.

The analyses attest the excellent psychometric properties of the German translation of the IEQ and so the German-language version of the IEQ can be used as a validated questionnaire to screen for perceived injustice.