title: Conceptual equivalence and health-related quality of life: an exploratory study in Japanese and Dutch cancer patients.
abstract: 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.
authors.affiliation: Medical Psychology, Leiden University Medical Center, P. O. Box 9555, 2300 RB, Leiden, The Netherlands. w.c.kleijn@lumc.nl
authors.forename: W Chr
authors.initials: WC
authors.lastname: Kleijn
authors.forename: K
authors.initials: K
authors.lastname: Ogoshi
authors.forename: K
authors.initials: K
authors.lastname: Yamaoka
authors.forename: T
authors.initials: T
authors.lastname: Shigehisa
authors.forename: Y
authors.initials: Y
authors.lastname: Takeda
authors.forename: C L
authors.initials: CL
authors.lastname: Creutzberg
authors.forename: J W R
authors.initials: JW
authors.lastname: Nortier
authors.forename: A A
authors.initials: AA
authors.lastname: Kaptein
mesh_terms: D001294:Attitude to Health / Q000208:ethnology*; D003431:Cross-Cultural Comparison; D003469:Culture; D005260:Female; D006801:Humans; D007564:Japan; D008297:Male; D009369:Neoplasms / Q000208:ethnology* / Q000523:psychology*; D009426:Netherlands; D016522:Oncology Service, Hospital; D010865:Pilot Projects; D011594:Psychometrics / Q000295:instrumentation*; D011788:Quality of Life; D018434:Sickness Impact Profile; D011795:Surveys and Questionnaires