Translation and Cross-Cultural Equivalence of Health Measures

1. Translation and Cross-Cultural Equivalence of Health Measures

2. Context: why are we interested? • Multinational drug trials need to ensure products are tested in standard way in different countries. • Cross-cultural research within countries • International health studies (WHO, etc.) • Evidence-based medicine: how confident can I be that results of a clinical trial overseas would apply here?

3. Translation • Simply translate an instrument and administer it • Simple tests of difference: assumes scalar equivalence • Almost certainly inadequate • Translation + back translation

4. Issues to Consider • Do you wish to adapt the measure for a new country, or make comparisons across countries? • Should it be a strict translation or an adaptation? • Back-translation gives linguistic identity rather than equivalence • Example of memory item in a dementia screen “In what year did the first world war begin?” • In most countries the ‘official’ language differs from the vernacular. Which do we use? • We often ignore linguistic variations within countries

5. Translation, or Domination? Bias in cultural assumptions illustrated by a statement (circa 1955) by Alexander Leighton: “…with refinements and changes introduced here and there in order to convey the meaning of the English questions as accurately as possible…”

6. Issues - continued • Why was this instrument chosen? Is the content truly relevant in another culture? • At least some of the content of most scales is culture-specific (e.g., some of NHP seen as blasphemous in Arabic countries) • Was the scale developed on a particular cultural group?

7. Words & cultural concepts • An etic approach to language (phonetic) describes the physical properties of the word, without referring to its functional meaning: language • The emic approach takes account of the context, meaning and purpose of a word: concepts

8. Translation Example • “Does poor health prevent you from seeing your friends?” • Be careful: meaning of “friend” differs in UK, US, and Australian forms of English • Even more differences between Ami(e), Amigo and Freund

9. Relevance of Culture • Culture shapes the way we conceive of health and illness: it influences the attention paid to symptoms, reactions to pain, etc. • Expectations & definitions of feeling good, etc. • It influences customary behaviours, relationships with others, including people with clip boards & questionnaires: the ‘questionnaire sophistication’ of the group. • It affects the way we interpret the language used in our questionnaires.

10. Level of abstraction • Concepts can be: • Abstract but general • E.g., Happiness, Ability • These terms probably apply in different cultures, but are imprecise and subjective: their meaning may differ. • However, being subjective may be sufficient in itself: perhaps a person’s subjective answer is inherently valid. (Discussion point: Maybe it doesn’t matter if happiness means slightly different things in different cultures?) • Concrete and specific • Number of hospital beds per capita • You can compare these across cultures, but • They are very context-dependent so less cross-culturally comparable.

11. Establishing Cross-Cultural Equivalence • Are you using the same general measurement procedures? Or, at least culturally equivalent approaches? (This could mean using different words) • Item equivalence: items should mean the same thing to people in one culture as in another • Scale equivalence (e.g., is the distance between “moderately severe” and “severe” the same in both cultures? Will respondents feel comfortable with responses like “Disagree strongly”?)

12. Conceptual or Functional Equivalence • Is the theme being measured really a universal experience? • Does this construct mean the same thing in both cultures? (How do we know this?) • Does it matter that a theme such as quality of life has a different range in 2 cultures? Should it be measured relative to local expectations, or in an absolute way? • Do the same cause-effect relations exist in each culture? • Does a similar situation lead to similar behaviours across cultures? (E.g., sick enough to go to a doctor)

13. Item equivalence • Items should mean the same thing to people in one culture as in another • And be similarly difficult • E.g. on FAS test, items with identical meaning in French are not FAS, but T, N and P • Translating items such as “No ifs, ands, or buts” (in the 3MS cognitive screen)

14. Scalar Equivalence • Measured on the same metric • Numerical values may appear culturally equivalent, but using numbers can mask differences in how they are introduced. • E.g. is the upper end of the scale defined in the same way in the instructions in both cultures?

15. Developing cross-cultural measures • Sequential approach • Translate an instrument into another language • Simultaneous approach • Conceptualize & develop measure in each culture • Set of equivalent items that reflect the same construct in different cultures • Core instrument plus culture-specific additional components

16. Common strategies for ensuring cross-cultural equivalence • Direct translation and comparison • Better translation techniques • Multi-trait, multimethod matrix • Item response theory methods • Differential item functioning

17. Strategies, continued • Response pattern method • Factor analysis • Multidimensional scaling • Combined etic-emic approach • Multi-strategy approach

18. Factor analysis • Empirical analysis of how items relate to one another • Shows how many concepts scale measures and which items measure that scale • Confirmatory: must have theory about how items go together • Simultaneous factor analysis in different populations • Factor structure should be the same • Test whether data are similar to be called equal • Same factor pattern-loadings • Same goodness of fit

19. Differential Item Functioning (DIF) • Related to IRT theory • DIF = a difference in an item score between two groups who are equal in ability (e.g. as indicated by equal overall scores) • Needed because tests can have matching factor structures and still be biased.

20. DIF analyses • Involves comparison of 2 or more groups (e.g. different languages) • Step1: match people on ability (total score) • 2nd step: for each score group, compares performance of reference and focal group on each item • In translation from English to French, English is reference, French focal

21. Two types of DIF • Uniform • Difference in item difficulty between reference and focal group • Item may be more difficult for one group (perhaps translation problem?) • Non-uniform • Difference in discrimination between reference and focal group

22. Correcting DIF or non-factorial equivalence • Study reasons why • Content experts • Review item wording, translation, cultural meaning.

23. Translation & cultural equivalence suggestions • Plan cross-cultural applications from the outset • Consider relevance of quality of life carefully: omit? • Avoid questionnaires! • Use ‘DIF’ analyses • Run within-country analyses • Develop measures within each country • Search for a core set of universal items (WHO QoL) • Make sure the values are explicit