Investigating and improving the German response scales of the EORTC core questionnaire for assessing the quality of life in cancer patients (EORTC QLQ-C30) – a three-step approach

EORTC QLQ-C30 scales are scored on a 4-point response scale, ranging from not at all to very much. Previous studies have shown that the German translation of the response option quite a bit as mäßig violates interval scale assumptions.
An optimized questionnaire version was developed by replacing the response option 3 mäßig through ziemlich, which fixed the interval scale issue. It was shown that the wording of the response scale had subtle but consistent impact on self-reported functioning and symptoms. This effect was pronounced in patients with a higher health burden.
The optimized response option should be used for the EORTC QLQ-C30 as well as for all other German modules.

All three steps of the study are completed. Results are ready to be published.

The final paper is now in the submission/review stage.

EORTC QLQ-C30 scales are scored on a 4-point response scale. It was shown that the wording of the response scale had subtle but consistent impact on reported functioning and symptoms.
An optimized questionnaire version was developed by replacing the response option 3 mäßig through ziemlich. This optimized response scale should be used for all German EORTC modules.