Reliability and validity of the Japanese version of the Diabetes Quality-Of-Life questionnaire for Japanese patients with type 2 diabetes mellitus

• Published in: Diabetology international 2014-03, Vol.5 (1), p.21-29
• Main Authors: Sato, Fumihiko, Mita, Tomoya, Yamamoto, Risako, Hirose, Takahisa, Ito, Chiharu, Tamura, Yoshifumi, Yokota, Ayako, Someya, Yuki, Uchida, Toyoyoshi, Uchino, Hiroshi, Kawamori, Ryuzo, Gosho, Masahiko, Ohmura, Chie, Kanazawa, Akio, Watada, Hirotaka
• Format: Article
• Language: English
• Subjects: Diabetes; Endocrinology; Medicine; Medicine & Public Health; Metabolic Diseases; Original Article
• ISSN: 2190-1678; 2190-1686
• DOI: 10.1007/s13340-013-0125-z

Objective Quality of life (QOL) is recognized as an important medical outcome. The aim of this study was to test the validity and reliability of the Japanese version of the Diabetes Quality-Of-Life (J-DQOL) questionnaire originally developed by the Diabetes Control and Complications Trial. Patients and methods The standard procedure for cross-culture adaptation was followed to develop the Japanese version of the J-DQOL. After linguistic validation, reliability was assessed by evaluating the test–retest reliability and internal consistency. Validity was also assessed by examining the floor and ceiling effects, factor structure, and construct validity. Results The responses of 298 of 319 patients with type 2 diabetes who volunteered to answer the questionnaire were analyzed. The J-DQOL and its four scales had high degrees of internal consistency (Cronbach’s alpha, 0.73–0.91) and test–retest reliability (intraclass correlation coefficients, 0.66–0.86). Floor effects were found in the categories of worry about social/vocational issues and diabetes. Also, factor analysis indicated that the J-DQOL structure was not completely consistent with that of the original DQOL. Construct validity was confirmed by relative correlation between J-DQOL scores only and certain components of the Diabetes Treatment Satisfaction Questionnaire, the Well-being Questionnaire, and the Beck Depression Inventory measures. Conclusions This study confirmed the reliability of the J- DQOL questionnaire and indicates that DQOL for Japanese patients with type 2 diabetes mellitus is not valid for assessing QOL, especially with regard to worry domains.