What is new?
Key findings- •
The concept of equivalence between languages in cross-cultural adaptation (CCA) of questionnaires in the literature involves different definitions and frameworks. The most comprehensive definition can be useful as a reference.
- •
We identified 31 different CCA methods in a review of the literature.
What this adds to what was known?- •
The methods of CCA can differ by their main focus (technical translation, focus groups, concepts, and so forth), but we lack evidence of the superiority of one method over another.
What is the implication and what should change now?- •
CCA of questionnaires is a delicate process. Any validated method can be used as long as its process is rigorous enough to achieve equivalence between the original and the translated questionnaire. More research is needed to provide evidence to support current guidelines.
Over the last decades, the number of self-report questionnaires, used in multiple fields of science, has increased exponentially. Often these questionnaires are meant to explore a construct that cannot be measured directly, quality of life being one example among patient-reported outcomes. These questionnaires are composite measurement scales (CMSs). A CMS consists of items or questions that assess one or several attributes scored by a scale. A construct consists of several attributes that are evaluated by a number of selected elementary criteria or items, each scored on a scale [1]. For clarity, we use the term questionnaire, which implies a CMS, in this article.
Creating a questionnaire implies expenditure of time and money, first to develop the questionnaire and choose domains and items that will best explore the construct of interest and second to validate the questionnaire, ensuring that it actually measures what it is intended to measure.
Cross-cultural research can be conducted to explore the same question in several cultures or measure differences across cultures. For either goal, researchers need the same questionnaire in different languages. If the questionnaire is available in another language, researchers should adapt a questionnaire with documented validity rather than create a new one because the cross-cultural adaptation (CCA) is faster and is assumed to produce equivalent measure [2]. This situation is true under the condition that the construct exists in the target culture and that the existing instrument measures it appropriately.
However, CCA of one questionnaire for another culture can be problematic. First, the translation can involve linguistic problems because two languages can have nonequivalent words or idiomatic expressions. For example, the word “fair” in English, which is often used in questionnaires, has no fixed equivalent in French and can be translated in two slightly different ways: “moyen” or “mediocre,” which would not elicit the same answer [3]. Second, the adaptation itself in another culture can be the problem because one item can have a very different meaning or no meaning at all in a specific cultural background. For example, in the Health Assessment Questionnaire (HAQ), people are asked if they can sit in their bathtub. For the Thai version of the HAQ [4], the adapter replaced the action of sitting in a bath by sitting to pay homage to a sacred image because in the Thai culture, people do not use bathtubs. Finally, the cultures can be so far apart that the way of thinking can be different [5].
A clear distinction should be made between translation, adaptation, and cross-cultural validation. Translation is the single process of producing a document from a source version in the target language. Adaptation refers to the process of considering any differences between the source and the target culture so as to maintain equivalence in meaning. This adaptation is referred to CCA. The cross-cultural validation of a questionnaire is a different process from the CCA. Cross-cultural validation aims to ensure that the new questionnaire functions as intended and has the same properties as the original and functions in the same way [6]. The adaptation and validation of a questionnaire are two different steps but can be part of an iterative process because if the questionnaire is not valid, the adapted version must be changed.
Many different methods of CCA exist, but none are considered the gold standard. Thus, reviewing the state-of-the-art methods of CAA and their respective level of evidence is useful.