Development of Japanese Versions of the Control Preferences Scale and Information Needs Questionnaire: Role of Decision-Making and Information Needs for Japanese Breast Cancer Patients

The importance of shared decision-making (SDM) between physicians and patients is increasingly recognized. In Japan, patients have shown more willingness to participate in treatment if medical professionals provide sufficient information; however, relationships between physicians and patients have traditionally been asymmetric, with patients accepting information from physicians without discussion. To explore the benefits of SDM in cancer treatment, including confidence in treatment decisions, satisfaction with treatment, and trust in healthcare providers, this study developed Japanese versions of the Control Preference Scale (CPS) and Information Needs Questionnaire (INQ). Reliability and validity of the CPS and INQ were tested with 49 breast cancer patients. The CPS showed good test-retest reliability (kappa coefficient: 0.61, weighted kappa coefficient: 0.61, Kendall's tau coefficient: 0.61) and acceptable criterion validity. The INQ showed adequate consistency; the mean number of circular triads and coefficient of consistency were 3 (range 0-19) and 0.9 (range 0.37-1), respectively. Using the CPS and INQ to identify patients' roles in decision-making and information needs, results further suggested that breast cancer patients in Japan want to participate in SDM. Medical issues, including disease spread and cure, were found to be of high interest, while social and psychological issues, including sexual attractiveness, genetic risk, and family impact, tended to be low. The Japanese CPS and INQ can be used to assess patients' needs to improve care. Further, as patients' information needs change along the care trajectory, these tools should be used throughout treatment.