Translation, Cultural Adaptation, and Initial Reliability and Multitrait Testing of the Kidney Disease Quality of Life Instrument for Use in Japan

Published In: Quality of Life Research, v. 10, Jan. 2001, p. 93-100

by Judith Green, Shunichi Fukuhara, Takahiro Shinzato, Y Miura, s Wada, Ron D. Hays, Rie Tabata, H Otsuka, Ichiro Takai, Kenji Maeda, et al.

Read More

Access further information on this document at Springer-Verlag Dordrecht

This article was published outside of RAND. The full text of the article can be found at the link above.

BACKGROUND: The Kidney Disease Quality of Life instrument (KDQOL) consists of 79 items: 36 asking about health-related quality of life (HRQOL) in general (the Medical Outcomes Study SF-36) and 43 asking about QOL as it is affected by kidney disease and by dialysis. AIM: Translation, cultural adaptation and initial reliability and multitrait testing of the KDQOL for use in Japan. METHODS: Translation and cultural adaptation began with two translations into Japanese, two backtranslations into English, and discussions among the translators, the project coordinators in Japan, and the developers of the original (US-English) version. Focus-group discussions and field testing were followed by analyses of test-retest reliability, internal consistency, and convergent and discriminant construct validity. RESULTS: All eight of the SF-36 scales met the criterion for internal consistency (Cronbach's alpha ranged from 0.73 to 0.92) and were reproducible (intraclass correlations between test and retest scores ranged from 0.60 to 0.82). Of the 10 kidney-disease-targeted scales, only two had x coefficients of less than 0.70: 'sleep' (0.61) and 'quality of social interaction' (0.35). One item on the 'quality of social interaction' scale had a very weak correlation with the remainder of that scale (r = 0. 10). Eliminating that item from scoring increased the x coefficient of the scale from 0.35 to 0.64. All three items on the 'quality of social interaction' scale had very strong correlations with other scales. CONCLUSIONS: First, in Japanese patients receiving dialysis the SF-36 scales are internally consistent and their scores are reproducible. Second, with the possible exception of the 'quality of social interaction' scale, the Japanese version of the KDQOL, can provide psychometrically sound kidney-disease-targeted data on quality of life in such patients.

This report is part of the RAND Corporation External publication series. Many RAND studies are published in peer-reviewed scholarly journals, as chapters in commercial books, or as documents published by other organizations.

Our mission to help improve policy and decisionmaking through research and analysis is enabled through our core values of quality and objectivity and our unwavering commitment to the highest level of integrity and ethical behavior. To help ensure our research and analysis are rigorous, objective, and nonpartisan, we subject our research publications to a robust and exacting quality-assurance process; avoid both the appearance and reality of financial and other conflicts of interest through staff training, project screening, and a policy of mandatory disclosure; and pursue transparency in our research engagements through our commitment to the open publication of our research findings and recommendations, disclosure of the source of funding of published research, and policies to ensure intellectual independence. For more information, visit

The RAND Corporation is a nonprofit institution that helps improve policy and decisionmaking through research and analysis. RAND's publications do not necessarily reflect the opinions of its research clients and sponsors.