Validity and Reliability of the Japanese Version of the 10-Item Perceived Efficacy in Patient-Physician Interactions (PEPPI-10) Scale in Breast Cancer Outpatients

The 10-item Perceived Efficacy in Patient-Physician Interactions (PEPPI-10) questionnaire was used as an indirect measure of the patients' perception of the strength of their therapeutic connection with their physician. The English version of the PEPPI-10 could serve as a valuable research tool for analyzing the relationship between patient and physician. The incidence of breast cancer is amongst the highest in Japan, and Patient Reported Outcome is often used as an outcome measure for breast cancer. It is particularly important to establish a strong patient-physician interaction for patients with breast cancer, since these patients require long-term treatment. We designed the present study to assess the reliability and validity of the Japanese version of the PEPPI-10 in female Japanese breast cancer outpatients. A cross-sectional study was performed at the Saitama Cancer Center, Japan. From August 2014 to August 2015, the Japanese versions of the PEPPI-10 that measure patient-perceived self-efficacy and the Brief Illness Perception Questionnaire (BIPQ) that measure illness perception were used for 92 breast cancer patients who received outpatient chemotherapy (mean age: 52.9 years, Cancer Stage I or Stage II : 82.6%, receiving adjuvant chemotherapy: 69.6%). We found that the Japanese version of the PEPPI-10 scale had a high coefficient of internal consistency (Cronbach's α coefficient, 0.83) for reliability, and concurrent validity analysis indicated that the utility of PEPPI-10 was moderately correlated with that of the BIPQ. In conclusion, the Japanese version of the PEPPI-10 is a useful tool that can empower breast cancer outpatients during the course of their treatment.