Discrepancies in the country versions of the WHOQOL-BREF as a potential source of error in assessing quality of life and a barrier to comparative research.

BACKGROUND: The aim of this study was to determine whether different language versions of the WHOQOL-BREF questionnaire allow for obtaining comparable health-related quality of life measurement results across different countries. METHODS: We analysed 21 country versions published on the World Health Organization website. Each version was compared to the reference English questionnaire in terms of its translation, the timeframe of measurement, the inclusion of instructions for respondents, visual layout, and additional elements. To evaluate the accuracy of the questions and scales, selected versions were reviewed by native speakers, and all translations were subsequently reviewed using a large language model. RESULTS: The results reveal substantial discrepancies between the versions across all evaluated criteria. In some cases, translation errors were so severe that responses to certain questions could not be meaningfully compared. CONCLUSIONS: We conclude that the WHOQOL-BREF questionnaire translations should undergo a comprehensive review to ensure conceptual and structural consistency and comparability. Additionally, language versions developed by external institutions should be carefully vetted by the WHO. The common practice of adding a note that a certain version is not an official WHO translation proves insufficient, as these tools are routinely treated by researchers and clinicians as de facto official instruments.