Using quantitative methods within the Universalist model framework to explore the cross-cultural equivalence of patient-reported outcome instruments.

Purpose: The cross-cultural equivalence of patient-reported outcome (PRO) instruments is critical when they are used in international settings. The Universalist model of equivalence was proposed as a framework to investigate cross-cultural equivalence. The purpose of this paper was to illustrate how quantitative methods can be used to investigate cross-cultural equivalence within this framework. Methods: The six types of equivalence of the Universalist model were reviewed from a statistical perspective and statistical techniques allowing addressing the underlying question were identified. These methods are described and examples are provided of how they can be applied. An integrated pragmatic approach to the exploration of cross-cultural equivalence was developed based on these methods. Results: The statistical techniques identified were factor analysis to explore conceptual equivalence, differential item functioning to explore semantic and item equivalence, and comparison of measurement properties for the measurement equivalence. The statistical techniques addressing operational equivalence were found to be diverse and highly specific to the operational aspect under investigation. Functional equivalence involves a comprehensive appraisal of the potential impact of the results of the other equivalences on the conclusions of the research. This structured appraisal of functional equivalence offers a framework for a comprehensive, but flexible, approach for the efficient application of statistical analyses to explore cross-cultural equivalence of PRO instruments. Conclusion: The different types of equivalence of the Universalist model can be investigated using quantitative methods. An integrated approach, which could be used in a variety of settings, was developed to allow the whole notion of cross-cultural equivalence to be comprehensively and efficiently addressed. [ABSTRACT FROM AUTHOR]