Utility of Equivalence and Cognition Models in Enhancing Validity of Translated Questionnaires: A Methodological Example Using the Heart Quality-of-Life Questionnaire

BACKGROUND: The cross-cultural adaptation of questionnaires has tenuous theoretical underpinnings that limit the rigor of data collection and the meaningful analysis of cognitive interview data. An adaptation of existing models of equivalence and cognition provides structure to the comprehensive investigation of various equivalence types in enhancing the validity of translated questionnaires.

PURPOSE: In this study, a framework comprising equivalence and cognition models was used to assess and finalize the Heart Quality-of-Life (HeartQoL)-Bahasa Malaysia (BM) questionnaire, which was derived from both forward-backward (FB) and dual-panel (DP) translation methods.

METHODS: Investigation and finalization of two initial versions of the questionnaire were conducted based on findings from an expert assessment (n = 3 sociolinguists blinded to translation methods) and cognitive interviews with purposively sampled patients (FB: n = 11; DP: n = 11). The equivalence model of Herdman et al. and the question-and-answer model of Collins were adapted to form a "cognition-and-equivalence" model to guide data collection and analysis through modified cognitive interviews. The final HeartQoL-BM was completed by 373 patients with ischemic heart disease from two medical centers, and the data were analyzed using confirmatory factor analysis to assess the evidence of equivalence.

RESULTS: Findings from the expert assessment and cognitive interview showed the existence of semantic and item equivalence on almost all of the FB and DP items, identified some subtle potential equivalence gaps, and guided the process of item finalization. Confirmatory factor analysis, including tests of factorial invariance on the final two-factor model of HeartQoL-BM, confirmed conceptual, item, measurement, and operational equivalence, which supports functional equivalence.

CONCLUSIONS: The potential use of the cognition-and-equivalence model for modified cognitive interviewing and the application of the six equivalence types of Herdman et al. were supported by the HeartQoL-BM showing functional equivalence with its source. HeartQoL-BM is a potentially valid measure of health-related quality of life for patients with ischemic heart disease independent of conditions such as angina, myocardial infarction, and heart failure.