Validation of the Japanese version of the full and short form Trust in Oncologist Scale

Objectives This study aimed to validate the Japanese versions of the Trust in Oncologist Scale (TiOS-J) and the TiOS-Short Form (TiOS-SF-J). Methods A cross-sectional web-based survey was conducted among cancer patients in Japan. The forward-backward translation method was used to develop the TiOS-J. The web-based survey was mailed to 633 people, of whom 309 responded. After 2 weeks, 103 among the 156 first-time respondents completed the second survey to verify the reliability of the retest method. The validity was evaluated by exploratory factor analysis (EFA), confirmatory factor analysis (CFA), Spearman's correlation coefficients between the Patient Satisfaction Questionnaire-Japanese, willingness to recommend the oncologist, trust in health care, and number of oncological consultations. To evaluate reliability, Cronbach's α and test-retest correlation were calculated. Results The theoretically driven four-factor model and the EFA-driven one-factor model of the full-form TiOS-J (18 items) did not result in an acceptable fit; however, CFA supported the one-dimensionality of the 5 items from the TiOS-SF-J (χ2 (5) = 12.36, p = 0.03, goodness-of-fit index = 0.984, adjusted goodness-of-fit index = 0.952, comparative fit index = 0.991, and root mean square error of approximation = 0.069). With regard to the reliability of TiOS-J and TiOS-SF-J, the Cronbach's alpha values were 0.94 and 0.89, respectively; the test-retest values were 0.82 and 0.78. Significance of Results This study indicated that the TiOS-J and TiOS-SF-J are valid and reliable instruments for measuring patients' trust in their oncologists and can be used to assess trust in oncologists for both clinical and research purposes.