摘要：Background
The European Organization for research and Treatment of Cancer (EORTC) Core Quality of Life Questionnaire (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, and that
ziemlich is a more appropriate translation. The present studies investigated differences between the two questionnaire versions.
Methods
The first study employed a balanced cross-over design and included 450 patients with different types of cancer from three German-speaking countries. The second study was a representative survey in Germany including 2033 respondents. The main analyses included compared the
ziemlich and
mäßig version of the questionnaire using analyses of covariance adjusted for sex, age, and health burden.
Results
In accordance with our hypothesis, the adjusted summary score was lower in the
mäßig than in the
ziemlich version; Study 1: − 4.5 (95% CI − 7.8 to − 1.3),
p = 0.006, Study 2: − 3.1 (95% CI − 4.6 to − 1.5),
p < 0.001. In both studies, this effect was pronounced in respondents with a higher health burden; Study 1: − 6.8 (95% CI − 12.2 to − 1.4),
p = 0.013; Study 2: − 4.5 (95% CI − 7.3 to − 1.7),
p = 0.002.
Conclusions
We found subtle but consistent differences between the two questionnaire versions. We recommend to use the optimized response option for the EORTC QLQ-C30 as well as for all other German modules.
Trial registration: The study was retrospectively registered on the German Registry for Clinical Studies (reference number DRKS00012759, 04th August 2017,
https://www.drks.de/DRKS00012759).
Supplementary Information
The online version contains supplementary material available at 10.1186/s12955-021-01866-x.
