Symptom-Management Self-efficacy Mediates the Effects of Symptom Distress on the Quality of Life Among Taiwanese Oncology Outpatients With Breast Cancer

Background: Theory has suggested that self-efficacy plays an important role in facilitating health behaviors and, in turn, promoting healthy outcomes. However, limited research has focused on the mechanisms through which symptom-management self-efficacy acts as a mediator between symptom distress and quality of life (QOL) for patients with breast cancer who have undergone chemotherapy. Objective: The purpose of this study is to examine the association between symptom distress and QOL among Taiwanese oncology outpatients with breast cancer and proposed symptom-management self-efficacy as a mediator between symptom distress and QOL. Methods: This cross-sectional study included 201 oncology outpatients in 1 teaching hospital in the Taipei area of Taiwan. The research instruments included the Symptom-Management Self-Efficacy Scale–Breast Cancer, the symptom distress scale, and the European Organization for Research and Treatment of Cancer Quality of Life Group Questionnaire. Bootstrapping was used to statistically assess the possible mediating effects of self-efficacy on QOL. Results: Symptom-management self-efficacy mediated the association between symptom distress and global QOL (indirect effect, −6.33; 95% confidence interval [CI], −9.63 to −3.74), functional QOL (indirect effect, −4.47; 95% CI, −7.05 to −2.36), and symptom QOL (indirect effect, 2.59; 95% CI, 1.07-4.83). All of the 95% CIs were significant. The lower symptom distress that patients experienced was indirectly associated with better QOL through higher self-efficacy. Conclusions: Symptom management self-efficacy may be a crucial mechanism through which symptom distress influences patients’ QOL. Implications: Clinicians may incorporate strategies focused on improving patients’ self-efficacy in relation to managing their symptoms caused by chemotherapy to improve patients’ QOL.