Conceptual equivalence and health-related quality of life: An exploratory study in Japanese and Dutch cancer patients

Medical Psychology, Leiden University Medical Center, P. O. Box 9555, 2300 RB, Leiden, The Netherlands.
Quality of Life Research (Impact Factor: 2.49). 08/2006; 15(6):1091-101. DOI: 10.1007/s11136-006-0049-1
Source: PubMed


Research into the equivalence of Western and Japanese conceptualizations of health-related quality of life (HR-QOL) is scarce. We used the Western (European Organization for Research and Treatment of Cancer, EORTC-QLQ-C30) and the Japanese (HRQoL-20) questionnaire in order to analyze the conceptual similarity of HR-QOL factors, and the associations between specific symptom items with overall HR-QOL in Japanese (n=265) and Dutch (n=174) patients with various types of cancer. Both populations completed both instruments. In both patient groups, the overall health scale of the EORTC-QLQ-C30 correlated highly (r=0.59; p<0.001) with the HRQOL-20 composite average score, indicating substantial conceptual comparability. Relationships between all EORTC-QLQ-C30 symptom items with HR-QOL were examined by ranking their correlations with the two overall measures of HR-QOL. Comparable patterns in the Japanese and Dutch samples were observed. The results suggest a considerable conceptual equivalence of HR-QOL in Japanese and Dutch cancer patients, and indicate a satisfactory structural and cross-cultural equivalence for the EORTC-QLQ-C30 with regard to items measuring functioning and specific symptoms. Longitudinal studies are needed to examine the impact of specific symptoms on general quality of life.

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Available from: Kazue Yamaoka, Sep 25, 2014
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    • "For the symptom scales, higher scores indicate worse symptoms. The Japanese version of the EORTC QLQ-C30 was developed following rigorous EORTC translation procedures and has been validated [32] [33] [34] [35] [36] [37]. The B-IPQ consists of 8 questions that measure 8 dimensions of illness perception (see Introduction) on a scale of 1–10. "
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    • "Two published articles contrasting the structure of the EORTC QLQ-C30 across multiple cultural/ethnic groups were identified, both based on relatively small samples. One suggested an equivalent factor structure for Caucasians and Asian/Pacific Islanders in Hawaii [7]; another found similar conceptual equivalence of the concept of HRQoL in the Netherlands and Japan [8]. Our previous analyses identified differential item functioning (DIF) in several items of the EORTC QLQ-C30 with respect to both translation and cultural group [9] [10]. "
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