Accurate measurement of outcomes relevant to patients living with rheumatic diseases is crucial to improve patient-centered care. The importance of well-validated measures is increasingly recognized in both research and clinical practice. Increasingly, research involves patients who complete outcomes in different languages. This occurs in countries with more than one common language, such as Canada (French/English) or Belgium (Flemish/French), as well as in international multi-centre collaborations. Multicenter collaborations are utilized frequently in the rheumatic diseases, in particular in rare diseases such as scleroderma. An important issue when pooling or comparing outcomes collected in different languages is that instruments should be measurement equivalent (invariant) across cultural or linguistic groups. This is because differences in the meaning of items due to translation or cultural differences in item interpretation can lead to responses that differ across groups even when levels of the outcome being measured are similar. Measurement differences between translated questionnaires can be a serious threat to the validity of cross-cultural comparisons, because when measures are not equivalent metrically, it is not possible to determine if any observed differences between groups reflect real differences or are a consequence of measurement artifacts (e.g., linguistic/cultural differences). Therefore, cross-cultural validity should be established if outcomes are to be pooled among study participants from different countries or used to compare results between patients from different cultural or linguistic groups. The objective of this presentation is to describe the rationale for and method by which measurement equivalent patient-reported outcome measures can be developed and evaluated.
Disclosure of Interest None declared